2025 poster Session

Brandt Bastow* | Adam Gilmore | William Drayton | Anita Oberholster

Rapid Detection and Risk Assessment of Smoke-Derived Volatile Phenols: A Chemometric Approach using Spectrofluorometry

Brandt Bastow,* Adam Gilmore, William Drayton and Anita Oberholster

*University of California, Davis, 677 Laugenour Dr., Woodland, CA, 95776, bpbastow@ucdavis.edu

The 2020 wildfires on the United States West Coast highlighted the urgent need for rapid, cost-effective methods to assess smoke exposure in wine. Analytical laboratories were inundated with samples, delaying results by over a month—an impractical timeframe for harvest decisions. Current assessment methods rely on mass spectrometry, which is accurate, but time-intensive and costly. To address these challenges, this research explores absorbance-transmission and excitation-emission matrix (A-TEEM) spectroscopy combined with chemometric modeling as a rapid alternative to quantify smoke-derived volatile phenols and their associated sensory risks. The study involves analyzing wine samples from multiple Northern California vineyards, spanning 10 varietals and several vintages. Sample preparation includes linear dilutions of severely smoke-affected grapes and wines to enhance detection of trace absorbance and fluorescence spectral signatures. Sensory analysis was conducted to determine the levels of various “smoke taint” attributes present in the wine. Single and multi-block chemometric models, employing multivariate and machine learning techniques, are currently being constructed by regressing A-TEEM spectral data against mass spectrometry and sensory analysis reference values. Statistical approaches under evaluation include gray classical least squares, parallel factor analysis, multivariate curve resolution, partial least squares, locally weighted regression (LWR), and extreme gradient boosting. Preliminary results demonstrate strong predictive correlations, with a LWR model achieving an R² of 0.997 for free guaiacol. A-TEEM demonstrates high instrumental repeatability (RSD < 2%), supporting the method’s robustness. This research aims to establish the efficacy of spectrofluorometry as a reliable, cost-effective tool for smoke taint risk assessment, enabling producers to make timely, informed decisions during wildfire-affected harvests.

Funding Support: CDFA 2021 Multi-State Specialty Crop Program

Lik Rong Lim | Elizabeth Tomasino*

Non-Contact Postfermentation Wine Processing to Remove Thiol-Related Smoke Compounds

Lik Rong Lim and Elizabeth Tomasino*

*Oregon State University, 100 Weigand Hall, Corvallis, OR, 97331, elizabeth.tomasino@oregonstate.edu

Global warming and climate change have increased the number of wildfire events during the grapegrowing season. The smoke-exposed grapes can result in smoke-tainted wines, which are perceived poorly by the consumer. Volatile thiophenols contribute to the ashy and smoke-tainted off-flavors in wine. Traditional sulfur mitigation methods for wine include adding copper sulfate as a fining agent which partly remains in the wine after bottling. However, copper sulfate is traditionally used on reductive related sulfur compounds and has yet to be thoroughly evaluated for removing volatile thiophenols in wine. It is also known to alter other wine aroma compounds. This work was done on a benchtop scale, with the goal of removing thiols without having the product come in contact with the wine and selectively removing only smoke compounds. An inert closed-loop system was devised, where thiophenols could be removed from the initial solution using a separate flask containing a thiol-selective trapping compound, – 5,5’-dithiobis(2-nitrobenzoic acid) (DTNB). This system ensured the trapping solution would not mix with the initial solution/wine. Previous work investigated the parameters suspected to influence trapping efficiency, including the concentration of thiol, the concentration of DTNB, the size and number of bubbles, the buffer solution used, and the temperature. The system is now being evaluated with a model wine spiked with smoke thiols to evaluate the trapping feasibility of the system. Future work includes testing on smoked-out wines and conducting sensory evaluations to determine if removing volatile thiophenols improves the perceived overall quality of the wine by consumers.

Funding Support: the USDA-Agricultural Research Service (ARS) project number 2072-21000-057-00D.

Connor Patton*

Wildfire Smoke-Taint Amelioration in Red Wines using Y Zeolite

Connor Patton*

*University of California, Davis, 2949 Portage Bay West, Apt 125, Davis, CA, 95616, cqpatton@ucdavis.edu

Wildfire smoke exposure of winegrapes leads to wines with an unappealing, ashy flavor and aroma. The ashy flavor and aroma is caused by absorption of smoke-related volatile phenolic compounds into the body of the grapes. Treatment of smoke-tainted wines involves introduction of Y-zeolite, a microporous, adsorptive aluminosilicate. The Y-zeolite is intended to selectively adsorb volatile phenolic compounds such as guaiacol, syringol, phenol, and cresol while limiting the removal of wine matrix compounds necessary to preserve the wine’s natural flavor, aroma, color, and texture. Addition of Y-zeolite to smoke-tainted California red wines for 1 hr with stirring resulted in 49 to 95% removal of free guaiacol, 4-methylguaiacol, o-cresol, 4-ethylguaiacol, p-cresol, m-cresol, 2,3-dimethoxyphenol, 4-ethylphenol, syringol, and 4-methylsyringol, and 18% removal of free phenol. The glycosidically-bound phenolics were only reduced in concentration by 36% reduction or less. Ethanol content of Y-zeolite treated wines only dropped by 0.4%, indicating limited competitive adsorption between ethanol and the volatile phenols. Future research will investigate the effect of Y-zeolite treatment on other volatile compounds in wine. The current findings indicate the potential of Y-zeolite as a viable material for smoke-taint amelioration. Further research will be performed to assess the viability of modifying the zeolite structure and composition to increase the adsorptive capacity and selectivity of the zeolites. These modifications include adjusting the silica/alumina ratio, loading the zeolite with metal atoms, and adjusting the pore and supercage sizes. For the research to be applicable in an industrial setting, the smoke-taint amelioration process will have to be continuous and capable of scaling up to an industrial volume. The findings of this study will demonstrate the capability of Y-zeolite to remove the smoke effects from wildfire smoke-tainted wines and the potential for doing so on an industrial scale.

Funding Support: California Department of Food and Agriculture

Gauthier Lagarde*

Barrier Spray Analyses for Mitigation of Smoke-Related Volatile Phenols in Cabernet Sauvignon Grapes

Gauthier Lagarde*

*UC Davis, 595 Hilgard Ln, Department of Viticulture and Enology, Davis, CA, 95616, glagarde@ucdavis.edu

Wildfires are a growing concern for the wine industry, as smoke-derived volatile phenols can significantly alter the sensory profile of wine, imparting undesirable smoky aromas and an ashy aftertaste. Smoke-tainted wines are thus compromised in flavor, typicity, and consumer acceptance. This study evaluates the effectiveness of Kaolin and GM3E as barrier sprays against smoke exposure. Whole grape bunches from 10 potted Cabernet Sauvignon vines were immersed in the respective spray solutions for 30 sec, with the sprays also applied to the leaves. Water was used for two control groups. The following day, three groups of vines (Kaolin, GM3E, and one control) were subjected to 4 hr simulated smoke exposure. The remaining control group was not exposed to smoke (negative control). One week after exposure, the grape bunches were collected and cleaned with water. The washed grapes and cleaning water were stored at -20°C. Free and total volatile phenols in the grapes and cleaning water were quantified by gas chromatography-mass spectrometry, while individual glucoside-bound volatile phenols were measured by liquid chromatography-mass spectrometry. Preliminary results show distinct differences between Kaolin and GM3E. GM3E treatment resulted in higher concentrations of free volatile phenols (337 µg/L) compared to the smoked control (184 µg/L). Kaolin showed lower levels (144 µg/L) than the smoked control, but still higher than the non-smoked control (34 µg/L). The distribution of volatile phenols also varied by treatment. For total volatile phenols, GM3E exhibited 9% of 2,3-dimethoxyphenol, while other treatments had less than 0.6%. Cleaning water contained more total volatile phenols in the GM3E treatment (53 µg/L) than in Kaolin (34 µg/L), smoked control (24 µg/L), or control (9 µg/L). These results suggest barrier sprays can alter the concentration and distribution of smoke-related phenols, providing insights into mitigating wildfire smoke effects on wine quality.

Funding Support: California Department of Food and Agriculture (CDFA)

Chen Liang* | Arran Rumbaugh | Ron Runnebaum | Francesco Maioli

Empacts of Methyl Jasmonate and Benzothiadiazole on Glycosylated Phenols in Grapes Exposed to Smoke Marker Compounds

Chen Liang,* Arran Rumbaugh, Ron Runnebaum and Francesco Maioli

*University of California, Davis, 595 Hilgard Ln, RMI North, Davis, CA, 95616, chelian@ucdavis.edu

During a wildfire event, smoke-exposed grape berries can uptake volatile phenols (VPs) such as guaiacol, cresols, and syringol. These smoke-taint related compounds can be metabolized into their glycoconjugates (Gly-VPs), transported, and stored in the grape cells. The Gly-VPs can be hydrolyzed during fermentation, wine aging, and consumption, releasing the VPs. The hydrolysis of Gly-VPs in mouth was reported to relate to the “smoky”, “ashy” off-flavor. Variations in grape Gly-VPs after smoke exposure were reported to improve evaluation of smoke taint risk. This study investigates the effects of human interventions in the vineyard after smoke exposure on Gly-VPs variation in grapes, seeking a way to mitigate smoke taint accumulation in grapes. Glycosylation of the VPs is a detoxification process of the grapevine. Application of natural or synthetic compounds can enhance plant defense responses and affect secondary metabolic pathways. Two such compounds are methyl jasmonate (MeJ) and benzothiadiazole (BTH). Both compounds were found to increase the phenolic content of grapes. This metabolic change could increase glycosylation of VPs, the same as for anthocyanin formation. Alternatively, formation of Gly-VPs could be decreased due to increasing glycosylation of endogenous phenols. To study the effects of MeJ and BTH on Gly-VPs variation in grapes, Cabernet Sauvignon grape clusters were exposed to aqueous mists of smoke marker compounds (guaiacol, p-cresol, syringol) at early postveraison. MeJ and BTH spray mists were applied one day after exposure, alone and in combination. Berry samples were collected at three time points. The glycosylated smoke marker compounds of each VP were detected in berries at harvest. The concentrations and changing dynamics of Gly-VPs in berries with MeJ and BTH applications will be reported and preferential uptake of the exposed three VPs will be documented.

Funding Support: USDA-ARS

Julie Hilland* | Thomas Collins | Robert Coleman

Validation of Protocols for Acid Hydrolysis of Smoke-Related Glycosides

Julie Hilland,* Thomas Collins and Robert Coleman

*Washington State University, 359 University Drive, Richland, WA, 99354, julie_hilland@wsu.edu

Wines produced from smoke-exposed grapes can exhibit undesirable sensory and palatable characteristics. The negative financial impact on a global scale for both grape and wine quality requires reliable methods to measure “free” volatile phenols (VP) and “bound” (VP-glycosides) in grapes and wine when evaluating smoke impact severity. Many analytical methods exist for gas chromatography-mass spectrometry (GC-MS) to quantify volatile phenols. These can also be applied to measuring VP-glycoside samples subjected to acid hydrolysis. However, there is currently no standard protocol for acid hydrolysis. This has contributed to inconsistent analysis results as protocols vary in application of acid, temperature, and duration. This project will develop and validate an acid hydrolysis approach to quantify VP and VP-glycosides in smoke-affected wines. A 30-L batch of model wine containing 5g/L KHTA and 14.75% alc (v/v) and adjusted to pH 3.30 was prepared. The amount of acid required to adjust samples to pH 1.0 and the amount of base to bring samples back to pH 3.5 was determined. Ten volatile phenols were added at 50 ug/L concentration each to the 30-L batch. VP-model wine samples were divided into two main categories: control and acid hydrolyzed. Samples were further divided into two subgroups: heated/non-heated and covered (watch glass)/uncovered. A hot water bath set at 80°C was used as the heating source. Unheated samples were placed on the laboratory counter at room temperature. Hydrolysis was conducted over a 4-hr period. Volatile phenol recovery using GC-MS was used to quantify and evaluate method success based on percent recovery. All tests were conducted in triplicate. The extent of variability across treatments will be used to improve acid hydrolysis protocols. Once validated, establishment of optimal pH, temperature, and time parameters by characterizing the hydrolysis reactions of known glycoside concentrations can be determined.

Funding Support: USDA/SCRI

Mitchell Davey | Markus Keller | Zilia Khaliullina | Danielle Fox | James Harbertson*

Examining the Role of Frost Damage on Leaf Composition to Unravel the Mystery of the “Frost Taint” Wine Phenomenon

Mitchell Davey, Markus Keller, Zilia Khaliullina, Danielle Fox and James Harbertson*

*Washington State University, 359 University Drive, Richland, WA, 99354-1671, jfharbertson@wsu.edu

Previous work demonstrated that frost-damaged leaves added to must prior to fermentation cause atypical floral aromas and floral aftertaste in Cabernet Sauvignon wines. The phenomenon is anecdotally referred to as “rose” or “frost” taint. In this work, leaf volatile composition was measured using untargeted solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS) to establish a relationship between wine, leaf composition, and varied aspects of leaf damage (temperature, aging, freeze drying) to study the phenomenon. Leaf composition analysis revealed that two previously identified chemical markers, 6-methyl-5-hepten-2-ol and p-menth-en-9-al, described as coriander and herbal aromas respectively, varied significantly based on frost damage (naturally frozen > freeze dried > control (not frost damaged). Volatile analysis of Cabernet Sauvignon wines made with naturally frozen, freeze-dried, and no leaves (8.0 g/kg) using untargeted HS-SPME-GC-MS found 26 compounds, primarily terpenoids and norisoprenoids, differed statistically between treatments, including 6-methyl-5-hepten-2-ol and p-menth-en-9-al. The results establish a chemical relationship between leaf and wine composition; however, we have not yet established a sensory relationship. Our results also expose the limits of using freeze-dried leaves in lieu of naturally frozen leaves to study the “frost” taint wine phenomenon.

Funding Support: Washington Wine Grape Funds Washington Wine Commission

Chanda Miller | Elizabeth Tomasino*

Investigation of Grape Skin Thickness and Grape Skin Lipid Content for Differences in Smoke Taint Composition

Chanda Miller and Elizabeth Tomasino*

*Oregon State University, 100 Weigand Hall, Corvallis, OR, 97331, elizabeth.tomasino@oreognstate.edu

A plant’s cuticle layer is an external waxy barrier to the lipid membrane and the plant’s first line of defense. The cuticle and membrane layers’ morphology and composition change in response to the fruit’s developmental stage and physiology. It is important to understand how developmental changes of these barriers affect fruit defense to environmental exposures. This work investigates the formation of smoke-related compounds and their relationship with the cuticle and lipid membrane layers of grape skins. In particular, it is of interest to determine if these two factors play a role in the different levels of smoke taint that arise within different varietals during the same smoke event. Twelve Vitis vinifera winegrape varietals (Cabernet Sauvignon, Cabernet franc, Merlot, Petite Verdot, Pinot noir, Syrah, Malbec, Tempranillo, Chardonnay, Viognier, Pinot gris, and Sauvignon blanc) were investigated. Grapes were harvested at two time points and smoked out in custom smoking chambers, as no natural event occurred that year. Skin thickness was measured using scanning electron microscopy and compared with smoked volatile polyphenol and smoked thiol concentrations to determine if there is a varietal difference in smoke taint. Skin lipid extraction was measured to determine if the lipid composition of the skin affects smoke taint formation.

Funding Support: Specialty Crop Research Initiative Grant #2021-51181-35862/project accession #1027470 from the USDA National Institute of Food and Agriculture and USDA-Agricultural Research Service (ARS) project number 2072-21000-057-00D

Lorenza Allen*

Innovative and Sustainable Wine Fining: The Science Behind Plant Proteins

Lorenza Allen*

*Enartis USA, 7795 Bell Road, Windsor, CA, 95492, lorenza.allen@enartis.com

The use of plant proteins in enology is gaining interest as a means to enhance winemaking performance while meeting market demands for sustainability and allergen-free alternatives. Traditionally, animal-derived proteins such as casein and egg albumin have been used for wine fining, but increasing concerns over allergies and sustainability have driven research toward plant-based solutions. Pea (Pisum sativum) and potato (Solanum tuberosum) proteins present promising alternatives, aligning with consumer preferences and industry trends. This study examines the chemical and physical characteristics of pea and potato proteins and their effectiveness as fining agents. Key factors in their production, including temperature and pH management, play a crucial role in optimizing their enological performance. Controlled hydrolysis was employed to enhance their reactivity, ensuring optimal results in wine clarification and stabilization. The findings indicate that plant proteins demonstrate strong fining capacity, reducing astringency and improving colloidal stability. Pea proteins effectively mitigate oxidation, while potato proteins interact more efficiently with astringent tannins. When subjected to appropriate hydrolysis, these proteins also show significant metal-chelating properties, particularly with iron, further reducing oxidative risk. Proper dosage is essential to achieve optimal performance while preserving the wine’s sensory balance. As sustainable and effective alternatives to traditional fining agents, plant proteins offer a viable solution to improve wine quality while addressing food safety concerns. This study provides a scientific foundation for their adoption, reinforcing the role of innovative, plant-based technologies in advancing the enological sector.

Funding Support: Enartis USA

Evaluating the Impact of Cool and Warm Climate on Grenache blanc and Viognier Wine Quality in California’s Central Coast

Coleman Imrisek, Mercy Torres, Ozan Gencer, Sean Kuster, Federico Casassa and Miguel Pedroza*

*California Polytechnic State University, San Luis Obispo, 1 Grand Ave, San Luis Obispo, CA, 93407, miguelp@calpoly.edu

Mediterranean grape varietals such as Viognier and Grenache blanc are known for adapting to diverse climatic conditions with a vocation to be sustainably dry-farmed. These grapes are increasingly considered viable alternatives to commercially dominant cultivars in California’s Central Coast, and the cool and warm climates in the region can be used as a model for assessing future climate change impacts, underscoring the need for comprehensive characterization of grape and wine quality. This work aims to provide a detailed chemical characterization of Viognier and Grenache blanc grapes and wines produced from cool (Santa Maria) and warm (Paso Robles) climate vineyards. We followed a 2 × 2 factorial design with vineyard climate (warm, cool) and varietal (Viognier, Grenache blanc) to compare the differences in grape composition, fermentation kinetics, and wine chemistry, including color, phenolic, and volatile composition, during the 2024 harvest. The wines were produced in triplicate using a standardized method across all treatments. Viognier wine made from cool-climate grapes was characterized by higher alcohol content and higher volatile terpene composition (linalool, geraniol, nerol, citronellol) compared to warm-climate wine. In contrast, Grenache blanc wine produced from cold climates was characterized by a higher concentration of volatile esters, lower total phenolic compounds, and lower alcohol and volatile acidity. Together, these results could be used by winegrowers to align climatic conditions with stylistic goals, such as producing varietal aroma-driven wines or increasing texture attributes and body in white wines.

Funding Support: Agricultural Research Institute

Evaluating the Impact of Cool and Warm Climate on Grenache and Syrah Wine Quality in California’s Central Coast

Coleman Imrisek, Dan Simon, Mercy Torres, Sean Kuster, Federico Casassa and Miguel Pedroza*

*California Polytechnic State University, San Luis Obispo, 1 Grand Avenue, San Luis Obispo, CA, 93407, miguelp@calpoly.edu

Grenache and Syrah are grape varietals known for adapting to diverse climatic conditions and producing distinctive wine styles ranging from medium to full body and varied levels of aroma, acidity, and alcohol. The California Central Coast offers an opportunity to characterize these varietals within a single region, but produced in cool and warm climates, which may be used by growers in different viticultural areas as a model to evaluate future climatic variability. This work aims to provide a detailed chemical characterization of Grenache and Syrah grapes and wines produced from cool and warm climate vineyards in Santa Maria and Paso Robles. We followed a 2 × 2 factorial design with vineyard climate (warm, cool) and varietal (Syrah, Grenache) and compared the differences in grape composition, fermentation kinetics, and wine chemistry including color, phenolic, and volatile composition during the 2024 harvest. The wines were produced in triplicate using a standardized method across all treatments. Results at the end of fermentation showed that Grenache wine from the warm climate had a lower content of anthocyanins ( -45%), and a higher content of tannin (+95%) and total phenolics (+59%) with respect to the cold climate wine. On the other hand, Syrah from the cold climate had higher alcohol (+0.7%), titratable acidity (2.34 g/L), color intensity (293%), tannin (25%) and total polyphenols (98%) with respect to warm climate. The preliminary results of this work clearly indicate a significant interaction between climate and varietal that should be considered by grapegrowers for alignment with wine stylistic expectations. Ongoing analysis of volatile compounds is expected to broaden the scope of this interaction.

Funding Support: Agricultural Research Institute

Natural Biopolymer-Based Coatings to Improve Water-Use Efficiency and Heat Tolerance in Cabernet Sauvignon

Xavier Rideout, Guadalupe Partida, Vincenzo Cianciola, Alessandro De Rosa, Adan Solis, Marco Saldivar, William Whalen and Luca Brillante*

*Department of Viticulture and Enology, California State University Fresno, 2360 E Barstow Ave, Fresno, CA, 93740, lucabrillante@csufresno.edu

Climate change has intensified droughts in California, posing challenges to viticulture. Elevated temperatures can reduce photosynthetic efficiency by limiting CO₂ assimilation, increasing photorespiration, and inducing physiological stress. Heat can also accelerate total soluble solids (TSS) accumulation, decrease acidity, and compromise fruit quality. To mitigate these effects, natural biopolymer-based coatings have been explored for their potential to modify plant water use and physiological responses. This study evaluates the effects of three biopolymer-based treatments: di-1-p-menthene (a terpene-based polymer from pine resin), xanthan gum (a microbial polysaccharide), and starch (a plant-derived polysaccharide) on water stress, leaf gas exchange, and vine physiology in Cabernet Sauvignon grown in the Central Valley. Treatments were applied at pre-veraison and veraison, with physiological responses assessed through gas exchange and stomatal conductance (measured using a LICOR-6800) and stem water potential (measured via pressure chamber). Fruit composition, including TSS, pH, and titratable acidity, was analyzed using high-performance liquid chromatography. Results indicated that starch application improved net assimilation after the second application without significantly altering stomatal conductance or stem water potential, demonstrating an improvement in water-use efficiency. Di-1-p-menthene application delayed ripening, leading to lower TSS accumulation while maintaining acidity, while xanthan gum accelerated TSS accumulation and slightly reduced acidity. At harvest, no significant differences were observed in yield components across treatments. These findings suggest that natural biopolymer-based coatings can influence vine water relations and fruit ripening dynamics, offering potential tools for drought adaptation. Starch may enhance carbon assimilation efficiency, while di-1-p-menthene could be leveraged to modulate ripening and acidity retention in warm climates. Further research is needed to refine application strategies, providing grapegrowers with sustainable solutions to improve resilience against climate change.

Funding Support: Bronco Wine Company Chair in Viticulture

Kaitlin Libbey | James Campbell | Larry Lerno | Susan Ebeler | Elisabeth Forrestel*

Environmental Drivers of White Winegrape Quality: A Survey of Chardonnay Ripening in Northern California

Kaitlin Libbey, James Campbell, Larry Lerno, Susan Ebeler and Elisabeth Forrestel*

*University of California, Davis, RMI Sensory, 392 Old Davis Rd, Davis, CA 95616, Davis, CA, 95616, ejforrestel@ucdavis.edu

Climate change is shifting the timing and conditions of winegrape berry ripening, affecting development and composition. Extreme heat during ripening can alter the nuanced balance of sugar accumulation, acid degradation, and aromatic potential in berries. These elements are particularly important for white wine grape cultivars, despite much less work focusing on climate impacts on white wine quality. To assess the relationship between climate and Chardonnay berry composition, we tracked the development of primary metabolites and aromatic precursors over the course of ripening in 22 different vineyards, spanning diverse microclimates in the North Coast wine regions. Rather than hydrolyzing bound compounds and using gas chromatography-mass spectrometry, we directly assessed the glycosidic aroma precursors using high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry. On-site weather stations, within-canopy temperature sensors, and stable isotope analysis (δ¹³C) provided insights into ripening conditions and their influence on aromatic compound accumulation. Further, differences in accumulation were observed between skin and pulp. Future work will apply these findings to the modification of current suitability indices (i.e., Winkler index) using finer-scale microclimatic data and additional quality parameters to inform cultivar selection for future climate resilience.

Funding Support: Winiarski Foundation, UC Davis College of Environmental and Agricultural Science, UC Davis Department of Viticulture and Enology

Hava Delavar | Harlene Hatterman-Valenti*

Phenotypic Characterization and Cold Hardiness Assessment in Vitis riparia and Vitis amurensis Mapping Populations

Hava Delavar and Harlene Hatterman-Valenti*

*North Dakota State University, 1360 Albrecht BLVD. Loftsgard Hall 470, Fargo, ND, 58102, h.hatterman.valenti@ndsu.edu

Freezing injuries cause an estimated 15% global grape production loss annually, presenting a significant challenge to sustainable viticulture. This study investigated phenotypic variations correlated with cold hardiness in two bi-parental mapping populations to explore potential markers for cold hardiness selection. Additionally, quantitative trait loci (QTL) mapping was conducted to identify QTLs that could accelerate cultivar development of environmentally resilient grape varieties. Two mapping families of 312 F1 hybrids from Vitis riparia × Vitis vinifera “Fresno Seedless” and 302 F1 hybrids from Vitis amurensis × V. vinifera “Valley Pearl” were examined. Differential thermal analysis was used to assess bud cold hardiness, complemented by comprehensive phenotypic trait measurements including bud water content, trunk and cane diameter, and postbudbreak phenology. Buds were analyzed after 7 and 28 days of cold storage at 4°C, examining low-temperature exotherms (LTE50). Significant variations were observed in cold hardiness and other phenotypic data. High-quality genetic linkage maps were successfully generated for both mapping populations, providing a crucial foundation for subsequent QTL analysis and marker identification. This research offers a potential sustainable strategy to develop cold-hardy grape cultivars that can maintain productivity under challenging environmental conditions and hasten the breeding processes in support of climate-adaptive viticulture.

Funding Support: Specialty Crop Research Initiative Competitive Grant, Award No. 2022-51181-38240, of the USDA National Institute of Food and Agriculture

Geraldine Diverres | Seanna Hewitt | Amit Dhingra | Markus Keller*

Soil Moisture and Soil Temperature Interact to Alter Grapevine Water Relations and Aquaporin Gene Expression

Geraldine Diverres, Seanna Hewitt, Amit Dhingra and Markus Keller*

*Washington state university, 24106 N Bunn Road, Viticulture and Enology, Prosser, WA, 99350, mkeller@wsu.edu

The combined effect of soil moisture and soil temperature on grapevine growth, yield, and fruit quality is gaining more attention in the context of global warming. However, their interaction and impact on grapevine physiology and water relations remain poorly understood. Grapevines can regulate water uptake in response to environmental changes by adjusting root aquaporin activity or gene expression. Published research shows that drought and cool rootzone temperatures limit plant water uptake and decrease root hydraulic conductance, possibly by reducing root aquaporin gene expression. Using custom-built pots in a climate-controlled growth chamber, we manipulated rootzone temperature independently of canopy temperature by recirculating chilled glycol or hot water to investigate the effect of soil moisture and temperature on gas exchange, leaf water potential (Ψ_leaf), and whole-plant hydraulic conductance (K_plant), using own-rooted Cabernet Sauvignon vines. Soil moisture was manipulated through irrigation management. After seven days, RNA was extracted from actively growing, unsuberized roots for RT-qPCR analysis. We focused on four Vitis vinifera plasma membrane aquaporins (VvPIP1;1, VvPIP2;2, VvPIP2;2, and VvPIP2;4N) for differential gene expression analysis. Our results show that the leaf-level responses were primarily influenced by soil moisture, while root aquaporin gene expression was more sensitive to soil temperature. Cooler root-zone temperatures reduced K_plant, stomatal conductance, and aquaporin gene expression. Soil moisture and soil temperature were correlated with Ψ_leafand K_plant, supporting the hypothesis of an interaction between these factors. The experiment was repeated to test different rootzone temperatures in 2024 and data analysis is still ongoing. During the last repetition in 2024, we observed that a sustained rootzone temperature of ~33°C for three consecutive days resulted in vine decline and death.

Funding Support: Washington State Grape and Wine Research Program; Chateau Ste. Michelle Distinguished Professorship in Viticulture

Madison Shaw | Devin Rippner | Jake Schrader | Michelle Moyer*

How Grow-Tube Type Influences the Vine Microclimate in Winter

Madison Shaw, Devin Rippner, Jake Schrader and Michelle Moyer*

*Washington State University, 24106 North Bunn Rd, Prosser, WA, 99350, michelle.moyer@wsu.edu

Cold injury is an issue for grapegrowers in regions with low winter temperatures. This injury often occurs when air temperatures drop faster than the vines can acclimate. There are viticultural practices that may exacerbate this risk of damage, including the use of grow tubes overwinter. We addressed this concern through a series of experiments that observed air temperature immediately surrounding Vitis vinifera Chardonnay vines when grown in paper, plastic, or no grow tubes during the 2024 to 2025 winter in eastern Washington State. The experiment used a randomized block design, with four replicates per treatment. Internal-tube temperate (or immediately surrounding temperature in the case of no tubes) was recorded every 15 min using HOBO data loggers; solar radiation was recorded at the nearby AgWeatherNet ‘Prosser’ weather station. Overnight, all treatments achieved the same air temperature immediately surrounding the vine. During the day, the range in temperature difference between paper tubes and no tubes was 3°C. This temperature difference range exceeded 14°C comparing plastic tubes to no tubes, with the air temperature inside plastic grow tubes being warmer than ambient air. The largest differences between ambient and plastic grow tube temperatures were generally associated with sunny days. Daily accumulated solar radiation was a positive predictor for increased daytime air temperature inside plastic grow tubes (R² = 0.58) over ambient air temperatures, but had no influence on the daytime air temperature inside paper grow tubes (R² = 0.007). We are also investigating the effect these daytime temperature swings have on bud cold hardiness. While preliminary, this study highlights the role grow tube material choice may have on vine winter temperature response. Results could be used to enhance cold-hardiness models for young vines, accounting for grow tube material choice and forecast weather conditions.

Funding Support: Washington State University, USDA National Institute of Food and Agriculture, Hatch project 7005262, and USDA-ARS project #2072-30500-001-000-D.

Gwendolyn Richards* | Cristina Lazcano | Charlotte Decock | Stewart Wilson

Assessing Carbon Saturation Potential of Regeneratively Managed Vineyard Soils

Gwendolyn Richards,* Cristina Lazcano, Charlotte Decock and Stewart Wilson

*Cal Poly San Luis Obispo, 1908 Corralitos Ave, San Luis Obispo, CA, 93401, gwendolynarichards@gmail.com

Soil carbon (C) storage is widely recognized as essential to both reducing atmospheric CO2 levels and improving soil health. Interest is rising among viticulturalists in California in adopting regenerative practices that store C. To optimize soil C storage, it is important to understand both its potential and limitations. It is well known that soil mineralogy constrains the potential of a soil for longer-term C storage. By assessing C saturation points of different soils, a vineyard’s soil C deficit can be determined and management can be catered accordingly. This study draws on soil samples from 87 vineyard soils with a long history of regenerative management to quantify the C saturation potential in California vineyards. The data set represents a wide range of soil mineralogical properties. Management practices include cover cropping, compost application, no-till, and grazing, with some practices adopted for up to 25 years. Soil organic C content across the data set ranges between 0.28 and 5.67%. To evaluate C storage potential, we plan to isolate two pools of C: particulate organic matter (POM) with a relatively fast turnover rate and mineral-associated organic matter (MAOM) associated with longer-term storage. In addition, all soil samples were analyzed for soil texture and oxalate extractable iron and aluminum. We aim to evaluate whether vineyards with a long history of regenerative management are reaching their C storage potential, and to determine the C storage deficit for participating vineyard blocks. Our findings will support new recommendations for promoting C storage in regenerative vineyards, taking into account mineralogical constraints.

Funding Support: Foundation for Food and Agriculture Research

Arbuscular Mycorrhizal Fungal Abundance and Diversity Across Vineyards in the Western United States

Amanda Rodriguez,* Joshua Garcia, Axel Herrera, Alicia Hans, Kerri Steenwerth, Kabir Peay, Elisabeth Forrestel and Cristina Lazcano

*University of California-Davis, 387 N Quad, Davis, CA, 95616, anrodrig@ucdavis.edu

Arbuscular mycorrhizal (AM) fungi are a well-known example of microbial symbiosis, playing a critical role in enhancing nutrient and water uptake, improving soil structure, and supporting ecosystem resilience. In winegrape production, where a balanced nutrient supply is vital to fruit quality, AM fungi facilitate soil exploration of essential nutrients and water, helping maintain optimal vine health and fruit development without promoting excessive vegetative growth. These benefits have spurred a global market for AM fungal inoculants, valued at $996 million, to enhance soil health and crop productivity. However, commercial inoculants face significant limitations, including high rates of nonviability and reliance on only a few fungal species. This contrasts with evidence suggesting that diverse native AM fungal communities often outperform commercial inoculants, underscoring the importance of understanding native AM fungal biodiversity and its interactions with grapevines under varying conditions. However, the extent to which AM fungi symbiosis is influenced by factors such as climate, soil properties, and plant genotype remains poorly understood. This study investigates AM fungal communities across 11 vineyards along an edaphoclimatic gradient from Oregon’s Willamette Valley to California’s Santa Maria Valley. AM fungal colonization was assessed through traditional microscopy and community diversity data was obtained from ITS2-targeted amplicon sequencing. These metrics of abundance and diversity were correlated with soil physical, chemical, and biological characteristics. Our study observed high colonization rates in all analyzed samples. Findings show regional soil and climatic differences shape AM fungal abundance and community composition. Our research aims to guide adaptive vineyard management strategies by providing crucial insights into the spatial dynamics of AM fungal interactions in vineyards.

Funding Support: Foundation for Food and Agriculture Research, California Department of Food and Agriculture

Jessica Williamson* | Richard Petrone | Riccardo Valentini | Andrew Reynolds

Variability in the Vineyard: A Multi-Method Approach in Determining Grapevine Evapotranspiration for Canadian Vineyards

Jessica Williamson,* Richard Petrone, Riccardo Valentini and Andrew Reynolds

*University of Waterloo, 161 Belmont Ave, Waterloo, Ontario, N2L 2B2, Canada, ja5willi@uwaterloo.ca

Vineyards are highly heterogeneous systems where climate, soil, and management parameters are capable of influencing water loss by evapotranspiration (ET) across many spatial and temporal scales. Water stress, which can be related to greater ET, may result in lower vigor and grape yield, while moderate water stress has been associated with improved grape and wine quality. This research was conducted across two separate vineyards in Beamsville and Jordan, Ontario, in the Niagara growing region during the 2022 growing season. To address vineyard variability in ET, a multi-method approach combining the use of a leaf-scale LI-6800 photosynthesis system, vine-scale sap flow sensors (Vinetalkers), block-scale atmometer ET gages, and vineyard-scale Eddy Covariance towers, was conceived. It was hypothesized that variability in climate-driven terroir controls would promote inconsistencies in crop ET between grape varietals at each vineyard. Results suggest that there is both spatial and temporal variability in ET, especially regarding white versus red grape varietals, as well as between phenological stages over the course of the growing season. Each method showed an increase in ET during the middle of the growing season, when full canopy cover was present and leaves showed no signs of water stress. ET rates typically declined towards harvest, which was associated with increased water stress and more optimal sugar concentrations in the grapes. Changes in air temperature, humidity, solar radiation, and wind speed caused variability in ET across each vineyard. This research presents an opportunity for growers to understand the current state of their vineyards and the spatial and temporal variability of their vines, allowing them to make specific, non-uniform, management decisions to enhance grape yield and quality each growing season.

Funding Support: Ontario Grape and Wine Research Inc., Global Water Futures, Agricultural Water Futures

Linking Soil Carbon Stability and Microbial Diversity at Different Soil Depths in Northern California Vineyards

Connie Wong,* Luisa Robles Zaragoza, Bruna Albuquerque Vaz, Ivan Martinez, Axel Herrera, Joshua Garcia, Kerri Steenwerth and Cristina Lazcano

*University of California, Davis, 1 Shields Ave, Plant and Environmental Sciences Building Rm 1110, Davis, CA, 95616, ctfwong@ucdavis.edu

Grapevine (Vitis vinifera L.) cultivation contributes to soil carbon (C) stabilization, the process by which organic C is retained in soil over time, reducing its decomposition and loss. Long-term stabilization depends on the balance between C inputs and microbial-driven losses. Soil depth influences stabilization mechanisms, including physical protection in aggregates, chemical interactions with minerals, and biochemical recalcitrance. Stable mineral-associated organic carbon (MAOC) forms when microbial by-products and organic compounds bind to mineral surfaces. In topsoil, microbial activity dominates due to greater organic matter availability, while physiochemical properties may play a greater role in subsoil stabilization. However, the role of microbial communities in subsoil C stabilization remains poorly understood. We examined the vertical distribution of C pools, including MAOC and other labile pools such as particulate organic C (POC), microbial biomass C (MBC), and dissolved organic C (DOC), in three Northern California vineyards with varying ages, grape varieties, and rootstocks, but similar management and soil textures. Furthermore, we evaluated the relationship between soil physicochemical properties (texture, pH, moisture), microbial activity, and diversity. We hypothesized that MAOC content increases with depth, while the labile C pools decrease. We also hypothesized that in topsoil, MAOC formation is primarily influenced by properties related to nutrient cycling and microbial activity. In contrast, at greater depths, factors such as pH and moisture content may be influential in maintaining MAOC stability. Results show that C pools generally declined with depth, with the youngest vineyard retaining the most subsoil C. Preliminary data suggest that the vineyard with the lowest soil C exhibited smaller microbial diversity changes with depth. Multiple regression analysis will assess the drivers of C stabilization at different depths. The results of this study will lay a foundation for evaluating the effects of soil management practices on C dynamics, microbial communities, and soil properties in California vineyards.

Funding Support: Foundation for Food & Agriculture Research; California Department of Food and Agriculture – Specialty Crop Block Grant

Untargeted Metabolomic Analysis of Heat Stress Response in Cabernet Sauvignon Grapevines

Samarth Rao, Brayden Hoke, Esther Ko, Karen Browning, Diana Zamora-Olivares* and Eric Anslyn

*The University of Texas at Austin, 2515 Speedway, Austin, TX, 78712, diana_z.o@utexas.edu

Worldwide, the United States is the fourth-largest wine-producing country, with 87% of grapes harvested from Vitis vinifera used for wine production. In Texas, where grape cultivation has a rich heritage and faces ever-increasing environmental challenges, understanding the physiological and metabolic responses of grapevine leaves to sustained heat stress is crucial to maintain crop quality and resilience. In this study, we investigated the effects of sustained heat stress on the secondary metabolite profiles of Cabernet Sauvignon grapevine leaves in a greenhouse with controlled temperatures (27 to 35°C). Experimental groups were subjected to heat treatment for 1, 3, 6, 10, and 13 days. Each heat-exposed group was further divided based on the timing of light exposure (morning versus evening), allowing us to assess the interplay between heat stress and light conditions. Control samples, harvested at corresponding time points without heat exposure, provided a baseline for comparison. Metabolites were extracted from leaf tissues and analyzed using high-resolution liquid chromatography–mass spectrometry for untargeted metabolomic profiling. Preliminary results revealed significant alterations in key secondary metabolites, suggesting that prolonged heat exposure triggers distinct metabolic reprogramming in grapevine leaves. Multivariate statistical analyses, including principal component analysis and partial least squares discriminant analysis, were employed to delineate correlations and identify potential biomarkers associated with heat-induced stress responses. This research represents one of the first efforts to discern the effects of heat stress on the secondary metabolite profiles of Texas grapevines. The findings not only enhance our understanding of stress physiology in grapevines but also pave the way for developing targeted strategies to improve crop resilience in a warming climate.

Funding Support: UT Austin

Chemical and Sensory Effects of Turbidity, Hyperoxygenation, and Redox Potential on Grenache blanc Wines from California

Mia Pargellis, Federico Casassa,* Biljana Petrova, James Nelson, Sean Kuster, Bob Coleman and Jesus Villalobos

*Wine and Viticulture Department – Cal Poly San Luis Obispo, 1 Grand Avenue, San Luis Obispo, CA, 93407, lcasassa@calpoly.edu

Grenache blanc wines were processed with hyperoxygenation (HO) and without, keeping it reductive using SO₂, inert gas, ascorbic acid and glutathione (RED) and adjusted to two contrasting NTU levels (low: 30 to 60; high: 280 to 320 NTU) prior to alcoholic fermentation (AF), affording four treatments: HO-lowNTU, HO-highNTU, RED-lowNTU, and RED-highNTU. After AF, average redox potentials (and total phenolics) were -90 mV (80 mg/L), – 94 mV (77 mg/L), -155 mV (142 mg/L), and -170 mV (143 mg/L), for HO-lowNTU, HO-highNTU, RED-lowNTU, and RED-highNTU, respectively. The ratio between reduced (GSH) and oxidized glutathione (GSSG) peaked at 152 and 129 in RED-lowNTU and RED-highNTU, respectively, while contrastingly remained between 2 and 3 in HO treatments, highlighting the contrasting redox status of the ferments. HO resulted in decreased absorbances in the 250 to 350 nm range, but increased absorbances in the 400 to 600 nm range throughout winemaking. While most terpenes were not affected by the treatments postferment, total ester content increased by 47% and 30% in HO-lowNTU and HO-highNTU wines, respectively, in relation to their RED counterparts. The basic chemistry of the wines (alcohol, pH, volatile acidity) was not altered. Sensory results from Pivot profile indicated that RED treatments showed greater color saturation and golden hue, with matchstick aromas and bitterness. HO-lowNTU was defined by banana aroma and HO-highNTU by floral, apple, and peach aromas. Control of the redox potential affords contrastingly stylistic sensory profiles in Grenache blanc wines, with effects of much lesser magnitude observed for turbidity.

Funding Support: Couch Family Wines and J. Lohr winery

Assessing the Impact of Skin
Contact, Redox Potential, and Hyperoxygenation in Albariño
Wines from California

Mia Pargellis, Federico Casassa,* Biljana Petrova, Sean Kuster, James Nelson and Bob Coleman

*Wine and Viticulture Department – Cal Poly San Luis Obispo , 1 Grand Avenue , San Luis Obispo, CA, 93407, lcasassa@calpoly.edu

Albariño wines were produced using six fermentation treatments: pressed white control (WhiteCon; daily full-volume pumpovers starting 1/3 through fermentation); pressed white reductive (WhiteReduct); pressed white hyperoxygenated (WhiteHO; daily full-volume pumpovers); skin contact control (SkinCon; daily punch-downs starting 1/3 through fermentation); skin contact reductive (SkinReduct); and skin contact white hyperoxygenated (SkinHO; daily punch-downs). Redox potential (ORP) was monitored during hyperoxygenation (HO). HO was achieved by injecting air at a rate of 5 cubic sq ft/hr for 2 hr, as confirmed by ORP of up to 376 mV (versus <100 mV in Reduct treatments). All skin contact treatments showed levels of tannins and total phenolics ~50 times greater than White ferments, and tannins levels were generally higher than those registered in average Pinot noir wines. Postalcoholic fermentation, WhiteHO showed the lowest color. Skin contact increased terpenes and resulted in ~5-fold increases of ethyl-cinnamate (fruity, balsamic) and methyl-salicylate (minty), but decreased esters by 50, 38 and 54% in SkinCon, SkinReduct, and SkinHO, respectively. Sensory results from Pivot profile indicated matchstick and curry aromas and the greatest overall aroma intensity in WhiteReduct wines. WhiteHO wines were defined by fruity notes (apple, lemon, melon, tropical). Skin contact increased astringency and bitterness, with enhanced minty notes in SkinReduct and coriander notes in SkinHO.

Funding Support: Couch Family Wines & J. Lohr wines

Kaolin and Zeolite Reduce Drought Damage to Gewürztraminer and Influence Berry Composition, Must Quality, and Wine Aroma

Stefano Zanoni,* Alessandro Bignardi, Sara Ammanniti, Silvia Carlin, Tomas Roman, Massimo Bertamini and Michele Faralli

*University of Trento (C3A, Centro Agricoltura Alimenti Ambiente), Via Mach 1, San Michele all’Adige, 38098, Italy, stefano.zanoni@unitn.it

Climate change is affecting Mediterranean viticulture regions due to frequent abiotic stress conditions such as drought and heat stress, which threaten grape and wine quality. Rock powders (Kaolin, Zeolite) have been identified as a possible adaptation strategy for abiotic and biotic stresses in grapevine. They influence leaf physiology and modify berry quality, thus wine characteristics, mainly by increasing organ reflectivity. This project assessed these rock powders’ influence on grapevine physiology (leaf gas-exchange, VPDleaf); berry sunburn incidence; and berry composition, must quality, and wine aroma. We investigated 3% kaolin and 3% zeolite in a 2-yr trial (2023 to 2024) on Gewürztraminer, an aromatic cultivar in northern Italy (Trentino Alto Adige), in an east-west oriented vineyard trained to a vertical shoot-positioned trellis system and Guyot pruned (two spurs, one fruiting cane, nine buds). Rock powders were applied to both canopy sides every 14 days and after rainfall in a randomized Latin-square design (252 vines, 3 rows, 12 plots each, n = 36), with bunch-zone leaf removal (No LR, LR BBCH75, LR BBCH81). Five and six applications were carried out in 2023 and 2024, respectively. Both kaolin and zeolite reduced leaf and berry temperature (p < 0.001, -6°C and -4°C, respectively), significantly limiting sunburn in berries (p < 0.05). Leaf physiology showed few differences between treatments, likely due to vintage-specific conditions, confirming that in rainy years, rock powders do not hinder ripening or physiological fitness, while preserving quality in hot/dry years. Some significant differences in aromatic compounds were found in musts and wine, however, wine tasting revealed no perceptible differences. Future studies will focus on the terpene biosynthesis pathway (MEP, MEV) under drought and heat stress to better clarify kaolin and zeolite effects on must and wine aroma.

Funding Support: University of Trento, Lithos Crop Protect GmbH

Amanda Fleming | Erika Gomez | Renee Threlfall*

Evaluating Methods to Measure Free and Total Sulfur Dioxide in Wine

Amanda Fleming, Erika Gomez and Renee Threlfall*

*University of Arkansas, 2650 N. Young Ave, Fayetteville, AR, 72704, rthrelf@uark.edu

Additions of sulfur dioxide (SO₂) during wine production are used to maintain microbial and color stability. The three chemical forms (molecular [SO₂], free bisulfite [HSO₃^–], and sulfite [SO₃^2-] vary depending on wine pH, but wine should have 0.5 to 0.8 mg/L molecular SO₂. Methods for SO₂analysis typically measure/calculate free, bound, or total SO₂ (sum of bound and free) using a standard method, aeration/oxidation (A/O) or colorimetric analysis. The accuracy, cost, and time for the A/O method and two colorimetric kits, Megazyme (Neogen^®) and BioSystems, to measure free and total SO₂in standard solution and wine (Vitis) samples were evaluated. For the standard solution samples, free SO₂ (12.5, 25, 50, 75, and 100 mg/L) and total SO₂ (50, 100, 200, 300, and 400 mg/L) were evaluated. For the wine samples, five co-fermentation treatments of Merlot (Vitis vinifera) and Noble (Vitis rotundifolia) wine were bottled at three molecular SO₂ levels (0, 0.8, and 1.5 mg/L) and evaluated. The A/O method cost $2.44/sample with a 25-min run time, Megazyme kits cost $5.13/sample with a 15-min run time, and BioSystems kits cost $4.50/sample with a 10-min run time. The A/O method offered accurate, timely, and cost-effective analysis of standard and wine samples. For standard SO₂ solutions, the Megazyme kit and the A/O method had the most accurate free and total SO₂,while the Biosystems kit was accurate for total SO₂, but not free SO₂. As Noble increased in wine samples, the kits had results that struggled to have total SO₂ levels that aligned with expected values. While kits provide faster options for analysis of SO₂, the reliability of the analysis differed per kit and sample type.

Funding Support: Research was funded by the Future of Food: Opportunities and Careers for Undergraduate Students (F2OCUS) Fellowship Program, an award from the National Institute of Food and Agriculture, United States Department of Agriculture (#2022-68018-36612). This research was also supported by funding from the Southern Region Small Fruit Consortium.

Danielle J Fox | James F Harbertson | Andrew L Waterhouse*

Detection and Identification of Glutathionyl-Flavan-3-ol Adducts
in Red Wine

Danielle J Fox, James F Harbertson and Andrew L Waterhouse*

*University of California, Davis, Department of Viticulture and Enology, Davis, CA, 95616, alwaterhouse@ucdavis.edu

Astringency, a key characteristic influencing the mouthfeel of red wine, is primarily attributed to the interaction between condensed tannins and salivary proteins. Tannins could undergo structural transformations by their ability to react with various nucleophiles, such as anthocyanins, bisulfite, and glutathione (GSH), over time as the wine ages, thus affecting the mouthfeel of the wine. In this study, we hypothesize that GSH in wine may interact with C4-carbocations during the acid-catalyzed depolymerization of tannins, resulting in the formation of glutathionyl-flavan-3-ol adducts. To investigate this, we employed targeted mass spectrometry (LC-QToF-MS) analysis to identify and quantify glutathionyl-flavan-3-ol adducts in a set of 24 red wines from Washington State, aged between 1 and 20 years. Our results revealed that these adducts were most abundant in the youngest wines (1-yr-old), with a notable decrease in peak intensity as the wines aged. The results indicate that the reaction is influenced by various factors, including GSH concentration, wine pH, and tannin content, all of which significantly affect the chemical structure of tannins and may play a crucial role in modulating astringency in wines. Future studies should focus on the long-term stability of glutathionyl-flavan-3-ol adducts and their sensory implications, particularly their effect on the perception of astringency and mouthfeel in aged red wines.

Funding Support: Washington State Wine Commission

Te Whenua Tupu Living Lab:
A New Facility for Soil and Ecosystem Research for Sustainable Horticulture

Cynthia Lund, Julian Theobald, Sue Neal, Damian Martin, Abby Albright,* Mark Seelye, Dion Mundy, Glenn Kirkwood and Stewart Field

*The New Zealand Institute of Plant and Food Research, 85 Budge St, Blenheim 7201, New Zealand, abby.albright@plantandfood.co.nz

Te Whenua Tupu (the Living Lab) is a new state-of the art facility at the New Zealand Wine Centre, established to become a world leader in the study of above- and below-ground perennial horticulture production systems, thus addressing the productivity, profitability, and environmental challenge priorities of the grapegrowing industry. The Living Lab (TLL) also serves to create a hub for collaborative research and education, to attract national and international talent, and enable agritech innovators to test and demonstrate new technologies and products. At the heart of TLL is a focus on biology, function, and the below-ground interaction of soil, microbes, and plants, integrated with aboveground biology and atmosphere. At an industry relevant scale and in one outdoor controlled environment, we can bring together a range of 1.7 m³ cored silt/sand/clay loam soils (with intact rooted plants of varying age and from various environments) or reconstituted gravelly soils, in bespoke cylindrical pots with integrated leachate collection and filled weights > 3.5 tonnes. Such large-scale has been deliberately incorporated to flexibly accommodate large soil volumes and a broad range of potential crops. We are developing whole-system capability for non-destructive root observation, minimally invasive rhizosphere biopsy, the mapping of detailed (3D) soil moisture depletion profiles, and accurate measurement of below-ground gas exchange and soil atmosphere composition. Aboveground, we are developing whole canopy gas exchange and phenotyping capabilities to closely monitor growing system architecture, carbon uptake, and allocation. The poster provides an introduction to the facility and its capabilities, including large-scale soil coring of grapevines and establishment of a networked soil sensor database and user interface pipeline. The poster and presentation have been updated from content described at Soil Rotorua in Dec 2024.

Funding Support: The New Zealand Institute of Plant and Food Research Nelson Marlborough Institute of Technology Marlborough Research Centre Trust

Axel Herrera* | Ellen Bruno | Kerri Steenwerth | Cristina Lazcano

Assessing the Economic Sustainability of Regenerative Viticulture in Sonoma County

Axel Herrera,* Ellen Bruno, Kerri Steenwerth, and Cristina Lazcano

*University of California, Davis, Department of Land, Air and Water Resources, Office 3310, Davis , CA, 95616, axherrera@ucdavis.edu

The transition to regenerative agriculture (RA) is gaining attention for its potential to enhance sustainability in viticulture, yet questions remain about its economic feasibility and environmental impacts. This study investigates the farm-level economic implications of transitioning to RA in the viticulture sector, with an application to California’s Sonoma County. We analyze data from four vineyards and evaluate the financial outcomes of implementing RA practices—such as no-till, composting, and livestock integration—compared to conventional viticulture practices. Our findings reveal that conventional and RA practices result in similar profitability over a 30-yr horizon, with RA averaging 0.54% to 1.63% lower in net present value across vineyards under the assumption of maintained yields. While in-house RA practices involve higher initial costs, they provide long-term benefits, including lower operational expenses, improved soil health, and additional revenue from sheep grazing integration. The profitability of RA is influenced by site-specific factors such as grape variety, vineyard layout, vine age, and density, as well as the ability to maintain yields or obtain price premiums that compensate for potential yield reductions. Given the variability in yield impacts across different grape varieties and vineyard conditions, site-specific assessments are crucial to inform the transition to RA.

Funding Support: California Department of Food and Agriculture (CDFA) and Foundation for Food and Agriculture Research (FFAR)

High-Resolution Approaches to Vineyard Nutrient Optimization

Nataliya Shcherbatyuk, Terry Bates, Manoj Karkee, Patricia Skinkis, Paul Schreiner and Markus Keller*

*WSU, 24106 N. Bunn Rd, Prosser, WA, 99350, mkeller@wsu.edu

Vineyard nutrient management is essential for maintaining vine health, productivity, and fruit quality targets. However, conventional vine tissue analysis methods are labor intensive, costly, and lack standardization and the ability to describe nutrient status spatially across vineyards. Our interdisciplinary team is refining tissue sampling techniques and creating decision-support remote sensing tools for real-time assessment of vineyard nutrient status. The project has four objectives: to 1) develop non-destructive tools to measure grapevine nutrient status; 2) determine the efficiency and suitability of precision vineyard nutrient management; 3) define grapevine nutrient thresholds based on the environment and production market; and 4) extend information and estimate the economic impact of nutrient management decisions. Nutrient prediction maps based on aerial spectral imagery and tissue samples were created for California and New York, while a ground-based imaging platform was used in Washington and Oregon. Field trials with nitrogen, potassium, and magnesium additions were conducted in Washington, Oregon, and Virginia. Tissue samples were compared across different growth stages from dormancy to leaf fall. Local events by project members reached state industries and the project podcast and website had reach from the local to international scales, with the podcast having over 4600 downloads and views from more than 30 countries. Although vineyard nutrient management is challenging, this project aims to enhance monitoring across the industry by refining assessment methods, improving tissue testing, and providing new tools and insights for more effective nutrient management

Funding Support: USDA National Institute of Food and Agriculture – Specialty Crop Research Initiative Coordinated Agricultural Project (award number 2020-51181-32159), Washington State Grape and Wine Research Program, Washington State Concord Grape Research Council, and USDA/WSDA Specialty Crop Block Grant Program.

Aude Watrelot* | Cain Hickey | Patricia A. Skinkis

Exploring Challenges and Needs of the United States Grape and Wine Industry: A Western Region Focus

Aude Watrelot,* Cain Hickey and Patricia A. Skinkis

*Iowa State University, 536 Farm House Lane, Ames, IA, 50011, watrelot@iastate.edu

Emerging wine regions commonly lack necessary knowledge and skills in grapegrowing and winemaking. However, viticulture and enology expertise exists and can be coordinated and optimized to improve the resiliency of these regions and the overall United States grape and wine industry. A transdisciplinary team of researchers and extension specialists with experience in a broad range of disciplines identified the primary challenges faced by grapegrowers and winemakers in these regions, and focus was placed on understanding resource needs. An online survey was conducted using a questionnaire that gathered demographics and quantified challenges in viticulture, enology, and winery business and marketing. This survey was distributed to grape and wine industry members across the U.S. in the first quarter of 2024. Data were analyzed and regional focus group meetings were conducted in four regions of the U.S., including West, Midwest, Northeast, and South, to discuss results and understand challenges further during spring 2024. Results of both the survey and focus group meetings were used to develop a national strategic plan for outreach/education and research. The survey and focus group results showed that while regions differ, they had common concerns. The main viticulture challenges were pest and disease management and the main enology challenges were acidity and microbial spoilage management. The evolving consumer preference was the main concern for wine marketing. More targeted research and extension programs are needed to manage those challenges in all U.S. regions. While variations existed across the states of the West region, the national challenges and needs remained consistent throughout. Findings of this project will be presented with a specific focus on the West region that includes data from OR, CA, WA, and CO.

Funding Support: U.S. Department of Agriculture, National Institute of Food and Agriculture, Specialty Crop Research Initiative Award number 2023-51181-41189

Aude A. Watrelot*

Effects of Varying Concentrations of Sulfur Dioxide at Bottling

Aude A. Watrelot*

*Iowa State University, 536 Farm House Lane, Ames, IA, 50011, watrelot@iastate.edu

Sulfur dioxide (SO₂) is widely used in the wine industry as a preservative due to its antimicrobial and antioxidant properties. However, growing health concerns have led to regulations that limit the total SO₂ concentration in bottled wines to a maximum of 350 mg/L. In response to consumer demand and the desire to reduce chemical inputs, winemakers often add varying levels of sulfites during bottling. Producing high-quality wine with reduced sulfite levels presents challenges, as it increases the risk of microbial spoilage and oxidation. This study investigates red wines made from cold-hardy grape varieties Petite Pearl and Marquette, produced using standard winemaking techniques and bottled with 30, 60, or 90 mg/L of free SO₂. The chemical parameters were analyzed both at bottling and after 4 mo of aging, including pH, titratable acidity, ethanol content, hue, color intensity, free and total SO₂, monomeric phenolics, tannins, and acetaldehyde contents. Results showed that higher concentrations of free SO₂ at bottling negatively affected color intensity in all wines. For Petite Pearl, wines with 90 mg/L of free SO₂ had lower acetaldehyde levels, while hue and the b* parameter increased. In contrast, no significant effects of free SO₂ concentration on hue or acetaldehyde levels were observed in Marquette wines. The study also included white wines made from La Crescent grapes and the findings will be presented. Overall, while a rational use of SO₂ can help maintain wine quality in cold-hardy red wines during aging, the effects may vary by grape variety, so further research is needed to assess the long-term effects of reduced sulfite levels on wine quality.

Funding Support: USDA-AMS Iowa Specialty Crop Block Grant Program (SCBGP) through USDA grant 23SCBPIA1187

Selective Phenolic Extraction During Cold Soak of Bordeaux Varietal Musts Using Bipolar Pulsed Electric Fields

Mafalda Aguiar Macedo,* Lauryn Allen, Jose Alberto Santos, Quinn Hubbard, Georgia Downes and Luis Manuel Redondo

*EnergyPulse Systems, Estrada do Paco do lumiar, Polo Tecnologico de Lisboa, Lt3, Sala 2, 1600-546 Lisbon, Portugal, mafalda.aguiar@energypulsesystems.com

Pulsed electric fields (PEF) are a valuable tool for winemakers, particularly in optimizing maceration processes. Innovative approaches by wineries like DAOU enables the rapid discovery and tailoring of PEF protocols to specific grape varieties. This study was conducted in an industrial setting at DAOU winery to determine the optimal PEF protocol for each variety and lot before industrial processing. Different bipolar PEF protocols (from 1.90kV/cm and ≈8.3kJ/kg to 1.4kV/cm and 4.8kJ/kg) were applied to high-quality grapes to produce four wine types: Cabernet Sauvignon (CS), Cabernet franc (CF), Merlot, and a blend of CS and CF. PEF treatments were delivered using a high voltage solid-state Marx generator (EPULSUS BM3B-15, EnergyPulse Systems), coupled with a P2P batch treatment chamber. PEF was applied at bench scale before a four-day cold soak (45ºF), followed by ADY inoculation. Maceration was monitored by evaluating total anthocyanins, free anthocyanins, bound anthocyanins, iron-reactive phenolics, and tannins. PEF significantly enhanced phenolic extraction across all varieties. Free anthocyanins increased up to 204% on day 1 and up to 98% by the end of cold soak. Total anthocyanins rose by at least 56.8% and up to 239%, with Cabernet Sauvignon showing the highest values. The key finding was that while tannin extraction was barely affected, bound anthocyanins increased from 17 to 79.6 mg/L, depending on the grape variety. This suggests that the PEF protocols not only enhanced anthocyanin extraction but also contributed to color stabilization. The higher bound anthocyanin content indicates that PEF can play a crucial role in stabilizing color compounds rather than only extracting them. These results highlight the potential of PEF to accelerate aqueous-phase color extraction, reduce mechanical intervention on grapes, and shorten maceration times, offering a promising tool for optimizing high quality red wine production.

Funding Support: Daou Vineyards and Winery and EnergyPulse Systems

Effects of Microoxygenation and Redox Potential Control by Air Sparging During Alcoholic Fermentation of Syrah Wines

Jordan Wright, Sean Kuster, Biljana Petrova, James Nelson, Bob Coleman and Federico Casassa*

*Wine and Viticulture Department – Cal Poly San Luis Obispo, 1 Grand Avenue, San Luis Obispo, CA, 93407, lcasassa@calpoly.edu

Syrah wines were made with two punch-downs per day (PD), air sparging activated upon oxidation reduction potential (ORP) < -40mV (SIN), microoxygenation (MOX) at a standard rate (PAR), and double the recommended standard MOX rate (2PAR) applied during alcoholic fermentation (AF). The concentration of acetaldehyde was greater in 2PAR and PAR compared to PD and SIN. Average ORP values were -16 mV and -14 mV for PD and SIN, and -51 mV and -56 mV for PAR and 2PAR wines. No differences were found in anthocyanins between all treatments. However, wine color, tannins, and total phenolics were greater in PAR and 2PAR wines than in PD and SIN wines, suggesting losses in PD and SIN wines or enhanced preservation in PAR wines. Concurrently, levels of reduced glutathione (GSH) were more than two times greater in PAR and 2PAR wines relative to PD and SIN wines. Epicatechin was 221% greater in PD than PAR wines. Total esters were 66% greater and 55% greater in PAR and 2PAR wines relative to PD wines, but generally, there were more terpenes in PD and SIN wines. At pressing, pH, titratable acidity, and ethanol levels were not affected by any of the treatments. Volatile acidity was lower and acetaldehyde levels greater in PAR wines relative to PD and SIN wines. MOX during fermentation proved a valid tool to achieve proper phenolic extraction and preserve the ester pool of the resulting wines, likely by keeping comparatively lower ORP during alcoholic fermentation.

Funding Support: Gallo & Parsec

Chemical Effects of Oxidation Reduction Potential on Syrah, Grenache, and Mourvèdre Wines
and Their Blends

Jordan Wright,* Biljana Petrova, Jesus Villalobos, James Nelson, Bob Coleman and Sean Kuster

*Wine and Viticulture Department – Cal Poly San Luis Obispo, 1 Grand Avenue, San Luis Obispo, CA, 93407, wjwright@calpoly.edu

Syrah (SY), Grenache (GRE), and Mourvèdre (MV) grapes were fermented in controlled (CON), reductive (RED), or oxidative (OX) fermentation (AF) environments. CON consisted of two pump-overs twice per day, RED consisted of 10-sec air sparges activated upon an oxidation reduction potential (ORP) < -80 mV, and OX consisted of 10-sec air sparges activated upon an ORP < 50 mV. ORP for CON SY ranged from -90 mV to -10 mV, CON GR from -70 mV to 120 mV, and MV from -120 mV to -40 mV. After AF, CON for each varietal were blended in equal parts (blCON) and replicated in RED (blRED) and OX (blOX) wines. There were no differences in anthocyanins, tannins, and total phenolics between CON, RED, and OX of both GRE and MV. However, there were significant differences in total phenolics (RED & CON > OX) and tannins (RED > OX) in SY. blRED and blCON had more phenolics and anthocyanins than blOX. Only blCON had higher concentrations of tannin than blOX. Differences were observed in catechin and epicatechin in MV (CON & RED > OX), while only CON > OX and RED > OX for catechin and epicatechin, respectively, in SY. CON GRE and CON MV were yellower in color than RED and OX at pressing. Overall, esters were much more abundant in RED treatments, except for ethyl isovalerate. For example, ethyl butyrate was 22% higher in GR RED than in OX. GR RED showed a 47% increase and MV RED showed a 20% increase in ethyl hexanoate compared to OX treatments. Hexyl acetate was 37% more abundant in GR RED and 58% more abundant in MV RED compared to GR and MV OX. Ethyl n-octanoate was 35% higher in MV RED than OX. Ethyl decanoate was 22% higher in GR RED and 37% higher in MV RED compared to OX treatments.

Funding Support: Couch Family Wines

Charlotte Drop* | Sean Kuster | Jesus Villalobos | James Nelson | Bob Coleman

Optimizing Strategies for Acid Management in Red Wines from the Central Coast of California

Charlotte Drop,* Sean Kuster, Jesus Villalobos, James Nelson and Bob Coleman

*Wine and Viticulture Department – Cal Poly San Luis Obispo, 1 Grand avenue , San Luis Obispo, CA, 93407, cdrop@calpoly.edu

Nebbiolo, Tannat, and Tempranillo wines from the Central Coast of California were produced using three acid management strategies with an untreated control wine. Treatments included blocking malolactic fermentation (MLFBlocked), fermentation with two strains of the lactic-acid producer Lachancea thermotolerans (Lach), and treatment with ion exchange (IE), followed by blending at a 30% proportion. Potassium levels in the Nebbiolo, Tannat, and Tempranillo fruit were 1400, 1650, and 2300 mg/L, while potassium levels in newly treated IE wines (before blending) were reduced to 137, 97, and 86 mg/L. Ca was also eliminated by IE. Across the three varieties, IE slightly increased titratable acidity (TA) by ~1 g/L and decreased pH by 0.30, 0.34 and 0.51 units in Nebbiolo, Tannat, and Tempranillo, respectively. MLFBlocked wines preserved their respective malic acid levels and showed on average ~1.1 g/L higher TA than control wines. MLFBlocked wines showed enhanced color, tannins, polymeric pigments, and total phenolics in Nebbiolo and Tannat wines, but not in Tempranillo wines. However, IE wines showed higher color and lower hue than control wines in all three varietals. Lach wines showed lactic acid levels ranging from 1.6 (Tannat) to 2.3 (Nebbiolo) (Laktia strain), to 5.8 g/L (Tempranillo) (Zymaflore Omega strain), and lower redox potentials than control wines (Nebbiolo: -60 and -74 mV; Tannat: -42 and -46 mV), except for Tempranillo (-78 and – 50 mV). Fermentation with Lach decreased esters by 60, 33, and 44% in Nebbiolo, Tannat, and Tempranillo, while MLFBlocked preserved or increased the ester content in the finished wines.

Funding Support: No funding

Aditya Anand | Brent Trela*

Haskap Variety and Winemaking Process Evaluations

Aditya Anand and Brent Trela*

*NCI, 1844 10th street N, Fargo, ND, 58105, trelab@hotmail.com

Haskap (Lonicera caerulea) plants are cold-hardy, with relatively novel berries that are of increasing interest to North American fruit winemaking. Berries from 11 haskap varieties (cv. Aurora, Boreal Beauty, Boreal Blizzard, Honey Bee, Indigo Gem, Kaido, Kawai, Keiko, Solo, Taka, and Tana) were stored frozen, measured for winemaking chemical parameters (titratable acidity [TA], malic acid, pH, soluble solid content, yeast assimilable nitrogen, color, and total phenolics), and fermented into wine using different winemaking protocols: 200 g berry micro lots and 13 kg berry macro lot fermentations, comparing continuous submersion, punch-down, and accentuated cut edge (ACE) maceration regimes over 1, 2, and 5 days, with two different water amelioration levels (35% and 8 g/L TA) on the pressed juice must volumes. Total phenolic concentrations were measured and sensory analyses conducted to select and rank the intensity of attributes from sensorial differences in aroma, mouthfeel, and taste on the whole fruit, pressed berry solids marc, and the finished wines to determine phenolic extraction by maceration regime. The use of ACE and continuous cap submerged wines from frozen haskaps resulted in higher pH and more total phenolics, red color, tannin, bitterness, and astringency compared to other methods. These assessments will describe the selected commercially available haskap varieties and the effects of common winemaking process choices, characterizing their chemical and sensory impacts. They will also support approximating macro volume cellar technique results on laboratory microscale and stylistic winemaking decisions.

Funding Support: Northern Crop Institute

Joy Ting | Lauren Moccio | Ann Sandbrook | Beth Chang | Dennis Cladis*

Ripening Kinetics and Grape Chemistry in Petit Manseng, a Non-Traditional Variety of Vitis vinifera

Joy Ting, Lauren Moccio, Ann Sandbrook, Beth Chang and Dennis Cladis*

*Virginia Polytechnic Institute and State University, Integrated Life Sciences Building, 1981 Kraft Drive, Blacksburg, VA, 24060, dcladis@vt.edu

Petit Manseng is a variety of Vitis vinifera valued in Virginia for its ability to consistently produce high quality grapes under variable, East Coast growing conditions. However, its high sugar and acid levels complicate dry wine production. This study characterized Petit Manseng ripening kinetics to inform harvest timing and winemaking decisions. Petit Manseng and Chardonnay were collected from veraison to harvest at six commercial sites over two years. Grape chemistry, including sugar and acid content, was analyzed for a total of 74 samples. The rate and timing of sugar accumulation and acid decline was described for both varieties, as well as the value at which physiological maturity was reached. Ripening kinetics were characterized using segmented regression analysis, principal component analysis (PCA), and linear discriminant analysis (LDA). The two grape varieties differed significantly in sugar accumulation and acid depletion throughout the harvest season. This was highlighted by the complete separation of Petit Manseng and Chardonnay grapes using PCA and the ability of LDA to correctly predict grape variety with 100% certainty using only titratable acidity and total soluble solids (TSS). However, when comparing malic acid and TSS, discrimination is lost, indicating that another acid (likely tartaric) is influencing this separation. As a result, vineyard practices to manage malic acid may not be effective in moderating acidity while cellar operations targeting tartaric acid (such as skin contact) may have more impact. Additionally, sugar accumulation in Petit Manseng results in a glucose:fructose ratio favoring fructose. Coupled with the high overall sugar concentration in Petit Manseng, a high proportion of fructose may lead to stuck fermentation and residual sugar. For winemakers seeking to produce dry style wine, use of fructophilic yeast coupled with diligent fermentation monitoring and prompt nutrient additions may be needed to successfully complete alcoholic fermentation.

Funding Support: The Virginia Wine Board

Carlos Perez Perez | Claudia Gonzalez Viejo | Sigfredo Fuentes | Juan Ignacio Valiente Banuet*

Proximal Multispectral Imaging
and Artificial Neural Networks for Assessing Grape Ripeness and Quality
in Vineyards

Carlos Perez Perez, Claudia Gonzalez Viejo, Sigfredo Fuentes and Juan Ignacio Valiente Banuet*

*Tec de Monterrey, Epigmenio González 500, Fracc, San Pablo, Querétaro/76130, Mexico, valiente@tec.mx

The integration of multispectral proximal sensing and artificial intelligence provides a precise approach to monitor grape ripeness and quality in vineyards. Our study utilized a multispectral camera operating across six wavebands: blue (475 nm), green (560 nm), red (668 nm), red edge (717 nm), near-infrared (842 nm), and thermal (8 to 14 µm) to capture multispectral imagery that was correlated with critical grape-quality data from Cabernet, Merlot, and Parellada grape cultivars from the 2022 and 2023 vintages. The physiochemical parameters of total soluble solids (TSS), titratable acidity (TA), pH, soluble phenols, and monomeric anthocyanins were estimated using machine learning models based on artificial neural networks. Eleven models were developed, encompassing two general models for red cultivars and Parellada and nine specific models targeting individual chemometric traits. Individual models exhibited robust predictive performance, achieving correlation coefficient values above 0.80 in all models. TSS had the highest correlation coefficient of 0.96 on red cultivars, while TA had the best performance in Parellada models, with a correlation coefficient of 0.90. General models for red and white cultivars effectively predicted all parameters with correlation coefficient values of 0.91 for each one. The study confirmed the reliability of these models, demonstrating no signs of over- or underfitting. Our findings highlight the potential of artificial neural network-driven multispectral sensing to facilitate automated quality trait assessment via unmanned terrestrial vehicles, paving the way for enhanced precision viticulture practices and vineyard management.

Funding Support: Tec de Monterrey (Queretaro) Ph.D. Scholarship Secreteria de Ciencia, Humanidades, Tecnología e Inovacion (México)- Scholarship (1104865)

Profiling Texas-Grown and -Produced Wines Using Untargeted Liquid Chromatography-Mass Spectrometry-Based Metabolomics

Delaney Dyer, Samarth Rao, Nicholas Bastia, Chloe O’Patry, Diana Zamora-Olivares* and Eric Anslyn

*The University of Texas at Austin, 2515 Speedway, Austin, TX, 78712, diana_z.o@utexas.edu

Texas is the fifth top wine-producing state in the United States, housing eight American Viticultural Areas and contributing $20 billion annually to the Texas economy. The wines of Texas have rich chemical diversity that reflects years of cultivation by expert winemakers and viticulturists. Studying the secondary metabolites that constitute environmental stress response in grapevines and wines has revealed valuable information about the resulting sensory features in finished wines. This information is becoming increasingly useful for winemakers to optimize wine quality and inform reproducibility across vintages. To our knowledge, no previous metabolomic studies on the biomarker profiles of Central Texas wines have been completed. The present study seeks to discover putative biomarkers in a selection of eight wines produced in Central Texas establishments using liquid chromatography-mass spectrometry (LC-MS)-based metabolomics and characterized their presence and significance in the metabolic profile of each varietal. Wine samples were collected from four vineyards in Central Texas and the metabolites were isolated via a liquid-liquid extraction. Following LC-MS submission, compound annotation in Compound Discoverer and principal component analysis and partial least squares discriminant analysis in MetaboAnalyst allowed for the identification of 537 putative biomarkers that significantly contributed to chemical differentiation in the wine samples. Resulting heatmaps and a standard data validation workflow revealed the relative concentrations and relevance of prominent biomarkers in each varietal sampled.

Funding Support: University of Texas at Austin

Deficit Irrigation Strategies for Sustainable Grapevine Production in the San Joaquin Valley: Three Years of Insights

Vincenzo Cianciola, Adan Solis, Marco Saldivar, Xavier Rideout, William Whalen, Eve Laroche-Pinel and Luca Brillante*

*Department of Viticulture and Enology, California State University Fresno, 2360 E Barstow Ave, Fresno, CA, 93740, lucabrillante@csufresno.edu

As drought conditions intensify in the San Joaquin Valley, grapegrowers face increasing pressure to optimize water use while maintaining productivity. This study evaluates the physiological responses of grapevines to different deficit irrigation strategies over three years, providing practical guidance for sustainable vineyard management. Conducted in a commercial Cabernet Sauvignon × 1103 Paulsen vineyard, this research assessed the effects of sustained deficit irrigation (SDI) and regulated deficit irrigation (RDI) strategies during the 2022 to 2024 seasons. A semi-autonomous irrigation system monitored actual water applications using flow meters. SDI treatments supplied 40, 60, 80 or 100% of crop evapotranspiration (ET_c), while RDI treatments adjusted water availability pre- and postveraison (e.g., 100/40, 80/60, 60/100). Stem water potential and gas exchange were measured from June through harvest, with grape composition monitored from veraison onward. Yield components were evaluated at harvest. While vines receiving 40% ET_c under SDI showed significant reductions in performance compared to the 100% ET_c control, RDI strategies and SDI treatments with moderate reductions in ET_c achieved similar or improved outcomes while conserving water. This study provides critical insights into the effects of deficit irrigation on vine water status, gas exchange, berry composition, and yield. The findings offer practical recommendations for growers seeking to enhance water-use efficiency without compromising grape quality, supporting the long-term sustainability of viticulture in drought-prone regions.

Funding Support: American Vineyard Foundation; California State University – Agricultural Research Institute

Creating a Practical Approach to Predict Grapevine Water Status by Precision Viticulture Technologies

Runze Yu,* Jesse Anastacio, Sho Murakoshi, Seiya Nishimura, Gen Sakoda, Takashi Takinami and Hiroyuki Okita

*California State University, Fresno, 2360 E Barstow Ave, M/S VR89, Fresno, CA, 93740, crzyu@csufresno.edu

Water is a crucial natural resource for vineyard production due to its significance in grapevine physiology. However, increasingly frequent drought conditions have significantly hindered vineyard productivity and grape quality in California. Grapegrowers must improve water use efficiency to mitigate these effects. This study investigated the integration of both soil moisture sensing and weather station data to predict grapevine stem water potential and provide practical help for grapegrowers to schedule irrigation in a hot viticultural region in California. The experiment was conducted in a Barbera vineyard in Fresno, California during 2023 and 2024. Four irrigation treatments were applied, including 50, 75, and 100% crop evapotranspiration (ET_c) replacement, and an over-irrigated condition. Three spatial frequency domain transmissometry sensors and three time-domain reflectometry (TDR) sensors were installed at depths of 20, 37.5, and 75 cm, along with an additional TDR sensor installed at 150 cm in one experimental replicate of each treatment. Weather data was obtained from the California Irrigation Management Information System station #80 at Fresno State. Grapevine stem water potential was continuously measured on-site across both seasons to train predictive models. Permutation feature importance (PFI) analyses were performed using all collected explanatory variables. Soil moisture at 75 cm, air temperature, and relative humidity emerged as the most significant variables in the well-performing models. The partial least squares model exhibited the most consistent and robust R² values, achieving R² = 0.7084 with two variables (soil moisture at 75 cm and air temperature) and R² = 0.7150 with three variables (soil moisture at 75 cm, air temperature, and relative humidity) predicting grapevine stem water potential. Overall, this study can provide practical and applicable knowledge to grapegrowers in hot viticultural regions to predict grapevine stem water status for irrigation scheduling.

Funding Support: Sony Semiconductor Solutions Corporation

Runze Yu* | Nazareth Torres | Sahap Kaan Kurtural | Justin D Tanner

Improving Vineyard Resilience Against Climate Change by Trellis Selection and Applied Irrigation Amounts

Runze Yu,* Nazareth Torres, Sahap Kaan Kurtural and Justin D Tanner

*California State University, Fresno, 2360 E Barstow Ave, M/S VR89, Fresno, CA, 93740, crzyu@csufresno.edu

Trellis selection is crucial to establish grapevine canopy architecture in winegrape vineyards, while irrigation plays a vital role in California viticulture. However, vineyard productivity and grape/wine quality are increasingly threatened by rising temperatures and limited water availability in many viticultural regions. This study evaluated the efficacy of various trellis systems and irrigation regimes in addressing these challenges in Oakville, CA during the 2020 and 2021 growing seasons. Six trellis systems were tested: traditional vertical shoot-positioned (VSP), two relaxed VSP systems (VSP 60 and VSP 80), a cane-pruned VSP (Guyot; GY), a single high wire (SH) and a high quadrilateral (HQ). Three irrigation treatments were applied: 25% crop evapotranspiration replacement (ET_c), 50% ET_c, and 100% ET_c. The SH and HQ trellis systems required more time to establish, but once mature, achieved higher yield and fruit maturity within the same growing season. Additionally, SH and HQ provided better canopy microclimates, reducing heat damage and preserving flavonol and anthocyanin concentrations. In contrast, VSP-based systems exhibited a greater risk of cluster overexposure to solar radiation and high air temperature. Lower water applications (25% ET_c) reduced yield but enhanced berry flavonoid concentration, suggesting a potential quality trade-off. Overall, this study highlights the need to transition from traditional VSP systems to more efficient and protective trellis systems and to adopt adaptive irrigation strategies to mitigate climate change effects and maintain grape and wine quality in warm-to-hot viticultural regions.

Funding Support: UC Davis Fellowships

Joy Hollingsworth* | Tian Tian

Calibrating a New Short-Wave Near-Infrared Spectroscopy Sensor for Measuring Table Grape Maturity

Joy Hollingsworth* and Tian Tian

*UCCE Tulare, 4437 S Laspina St, Suite B, Tulare, CA, 93274, joyhollingsworth@ucanr.edu

Felix Instruments has created a handheld sensor that uses short-wave near-infrared spectroscopy and a chemometric predictive model to determine a variety of fruit composition metrics, including total soluble solids (TSS), hue, and titratable acidity (TA), non-destructively and in real time. To improve the model, a large and diverse data set was needed. Beginning in summer 2022 and continuing for the next two years, our team collected data from 16 table grape varieties in the southern San Joaquin Valley. The varieties were chosen based on their production in California, and because they represented a wide range of colors (green, black, and red) and harvest maturities (early, mid, and late season). We used the sensor to scan berries from 10 to 20 bunches from each variety, one to three times per season. We then used standard laboratory instruments (refractometer, colorimeter, and autotitrator) to measure the TSS, hue, and TA from the same grapes and submitted the data to the company. Felix Instruments then incorporated the data into their new model using a combination of independent and hold-validations. Each year saw improvements in the accuracy of the model predictions. After the data from 2024 season was incorporated, the company realized the benefit of creating three models for table grapes, one each for green, black, and red varieties. The accuracy for TSS measurements was shown to be +/- 0.69, 0.64, and 0.85 Brix for the green, black, and red varieties, respectively. For TA, it was +/- 0.12, 0.10, and 0.14 g/100 mL. For hue, it was +/- 1.98, 83.87, and 27.41°. The F-751 Table Grape Quality Meter is expected to be launched in early 2025.

Funding Support: California Table Grape Commission

Marilyn García Tenesaca* | Jose Morales Ariza | Andreu Tobeña Montanuy

Advancing Tannin Quantification in Wines: A Rapid, Reliable Approach with Machine Learning and a BioSystems SPICA Analyzer

Marilyn García Tenesaca,* Jose Morales Ariza and Andreu Tobeña Montanuy

*BioSystems, Carrer Costa Brava, 30, Barcelona/08030, Spain, mgarcia@biosystems.es

Wine phenolic compounds are important secondary metabolites in enology due to their nutraceutical properties, their role in development of color and flavor, and the protection they offer from oxidation and spoilage. Tannins are particularly valuable for their contribution to mouthfeel and overall wine quality. However, the quantification of tannins remains challenging due to labor-intensive and complex methods. This study proposes a new automated method to quantify precipitable tannins during winemaking that is comparable to the widely used methylcellulose precipitation manual assay (MCP). Several physicochemical analyses—including anthocyanins, total polyphenols, color indices, catechins, and absorbance at 280 nm—were performed using the automated BioSystems SPICA analyzer, alongside ethanol content and pH. These analyses were part of a collaborative effort involving multiple laboratories, including BioSystems, several wineries, and university research groups. Different grape varieties (Cabernet, Chardonnay, Syrah, Tempranillo, and others) were analyzed, sourced from diverse regions (mainly in Spain, Chile, the United States, and France) and representing different winemaking processes, encompassing both must and finished wines. This variability in data sources significantly enhanced the robustness and reliability of the study. The reference value for precipitable tannins was determined using the MCP method. Machine learning tools such as multiple linear regression with regularization methods (i.e., ELASTIC NET, RIDGE) were applied to identify and describe the relationship between variables and the MCP method. The final predictive model achieved an R² of 0.72 on the test set, demonstrating strong alignment with the reference method despite inherent inter-laboratory variability. The proposed statistical modeling provides a reliable, fast, automated, accessible, and cost-effective solution for tannin quantification. Its robustness under real-world analytical conditions ensures broad applicability across various laboratory settings, wine types, and vinification processes, making it a valuable tool to optimize wine quality.

Funding Support: BioSystems

Yanxin Lin | Robert (Sui) Qiang | Misha Kwasniewski* | Bruce Pan

A New Method for Tannin Fingerprinting and Quantification
via LC-MS/MS-Electrospray Ionization
In-Source Fragmentation

Yanxin Lin, Robert (Sui) Qiang, Misha Kwasniewski* and Bruce Pan

*Food Science Department, Penn State University, Penn State University, Rodney A. Erickson Food Science Building, State College, PA, 16803, mtk5407@psu.edu

Tannins are a critical element of red wine quality, influencing mouthfeel, astringency, and aging potential. Wine tannins are categorized into condensed tannins (CTs), derived from grape skins and seeds, and hydrolysable tannins, including ellagitannins and gallotannins, introduced through oak aging and tannin additives. However, current analytical methods lack specificity, sensitivity, or require extensive sample preparation due to their structural complexity and polymerization variability. We present the development and validation of tannin fragmentation fingerprinting (TFF), a rapid LC-MS/MS method utilizing electrospray ionization in-source fragmentation for comprehensive characterization of both CTs and hydrolysable tannins. CT fingerprints are created by applying three cone voltages (30, 110, and 140 V) in the ion source to depolymerize the CT and generate in-source ions. The depolymerized spectra that contribute most to CT differentiation are further fragmented in the collision cell, using multiple reaction monitoring (MRM). MRM transitions from analytical CT standards are correlated to target samples via multidimensional linear regression, enabling comprehensive fingerprinting while retaining chromatographic information related to compound polarity. The method accurately predicted mean degree of polymerization (mDP) across 19 mixtures of five B-type CTs (DPs 1 to 5), demonstrating high accuracy and precision. Additionally, TFF has been adapted for high-throughput quantification of hydrolysable tannins, allowing precise differentiation of ellagitannins and gallotannins. Validation across 30 white wines and 33 red wines showed a strong correlation (r² = 0.98) with the acid hydrolysis method, which requires over four hours of sample preparation. The TFF method has been able to differentiate wines with subtle variations in tannin composition that other established methods would miss. It also has been optimized into a high-throughput approach for routine quantification that will significantly increase the information available in studies related to wine tannins.

Funding Support: None

Jose Morales Ariza* | Marilyn García Tenesaca | Andreu Tobeña Montanuy

Enhancing Precipitable Tannin Quantification: A Validated, Ready-to-Use Alternative to Traditional Methods

Jose Morales Ariza,* Marilyn García Tenesaca and Andreu Tobeña Montanuy

*BioSystems, Carrer Costa Brava, 30, Barcelona/08030, Spain, jmorales@biosystems.es

Tannins are essential phenolic compounds that influence wine color, taste, and protection against oxidation and spoilage. Precipitable tannins, typically larger and more structurally complex, are closely linked to sensory attributes like astringency. Quantifying these tannins provides insights into product quality, concentration, and their impact on flavor and texture. However, tannin determination is challenging, often relying on labor-intensive, time-consuming methods or complex techniques. The BioSystems tannins (precipitable) method, based on methylcellulose (MCP) capability to bind and precipitate tannins, is a semiautomated method to quantify condensed and hydrolyzable tannins in musts and finished red wines. Validation followed OIV guidelines using the BioSystems SPICA analyzer and wines from diverse origins and grape varieties. Key parameters such as linearity, bias, recovery, precision, limit of quantification, selectivity, interferences, stability, and robustness were evaluated. Recovery tests spiked samples with commercial tannins from grape skins, wood additives, and chemical additives. A comparative study with the MCP method, as defined by the Australian Wine Research Institute, was conducted on samples with tannin concentrations from 500 to 3500 mg/L. The method demonstrated its capability to measure condensed and hydrolyzable tannins from various sources and winemaking stages with enhanced precision, thanks to automation of 280 nm readings. Equivalent tannin concentration results were obtained using the MCP method and the BioSystems kit, which also showed satisfactory recovery rates and no interference with phenolic compounds. Reagent stability was significantly improved, confirmed by stress tests at 45°C, resulting in a kit with a shelf life of at least 18 mo compared to the reference method’s 7 days. The BioSystems tannins (precipitable) method provides ready-to-use, stable reagents and incorporates automation to streamline tannin analysis. By simplifying and improving tannin measurement compared to existing methods, it offers a reliable and efficient solution for monitoring tannin content in musts and red wines.

Funding Support: BioSystems

Characterizing Oregon Vineyard and Winery Brettanomyces Strains for Spoilage Potential

C. Michael Sonza, Emily Kaneshiro, Tess Snyder, Bjarne Bartlett, James Osborne and Christopher Curtin*

*Oregon State University, 232B Wiegand Hall, 3051 SW Campus Way, Corvallis, OR, 97331, christopher.curtin@oregonstate.edu

Brettanomyces bruxellensis is a well-known spoilage yeast that can cause economic losses due to blending or disposal of affected batches of wine. Although producers use mitigation strategies to prevent B. bruxellensis spoilage, variable efficacy in prevention of spoilage still occurs. Previous research linked this to differences in sulfite-tolerance between wine strains of B. bruxellensis, while mostly anecdotal evidence points toward certain vineyards carrying greater risk of spoilage occurrence. The extent to which sulfite-tolerant B. bruxellensis strains occur in Oregon wineries is unknown and few studies have evaluated the presence of B. bruxellensis in vineyards around the world. This study seeks to provide insight into these knowledge gaps by evaluating spoilage potential of B. bruxellensis stains isolated from Oregon wineries and vineyards. Building upon previous work, we successfully isolated 46 B. bruxellensis from winery samples representing 13 cellars in Oregon. Additionally, while we isolated 12 B. bruxellensis from vineyard samples previously, an additional 288 Pinot noir cluster samples are in the process of enrichment culturing to expand our collection. These samples are from 12 Oregon vineyards spanning the 2022 through 2024 harvests. Both wine cellar and vineyard isolates will be whole-genome sequenced, and the Oregon strains will be genetically compared against reference strains from other winemaking regions of the world, with a particular focus on identification of potentially sulfite-tolerant strains. The outcomes of this study will provide wine producers with an improved understanding of the spoilage potential of B. bruxellensis in Oregon, which will guide informed decisions to mitigate the risk of spoilage occurrence.

Funding Support: Oregon Wine Board and Oregon Wine Research Institute

Anne Flesch* | Evelyne Fonchy-Penot | Stéphanie Desroche-Weidmann | Arnaud Delaherche

Biofilm of Oenococcus oeni on Yeast Derivatives: Trigger Malolactic Fermentation, Modulate the Characteristics of Wine

Anne Flesch,* Evelyne Fonchy-Penot, Stéphanie Desroche-Weidmann and Arnaud Delaherche

*Fermentis, 7475 W Main St, Lesaffre Yeast Corporation, Milwaukee WI 53214, US, WI, 53214, a.flesch@fermentis.lesaffre.com

Malolactic fermentation (MLF) can occur naturally or be induced by inoculation of selected bacterial strains, most commonly Oenococcus oeni. Due to climate change, practices are evolving to adapt to more challenging conditions, especially increased alcohol content in wine, which is particularly harmful to the bacteria. Winemakers are deploying various strategies, including the use of newly-selected resistant lactic acid bacteria or the addition of yeast-derived nutrients to promote MLF. More recently, the use of bacterial biofilms has been described and investigated. A biofilm is a living community of one or more microbial species adhering to a surface and embedded in a self-produced polymeric matrix. However, the use of starters in biofilm form represents a major challenge, particularly because biofilms require abiotic supports (polystyrene, stainless steel, or wood) that may not be authorized additives. We have developed innovative biofilms of O. oeni on two different yeast-derived biotic supports: inactivated yeast and yeast hulls. The yeast derivatives have two initial objectives: immobilizing the bacteria to increase their fermentative ability and promoting fermentation. We will present the use of these biofilms in microvinification of Syrah and in comparison with the planktonic bacteria form, with or without the use of derived products (inactivated yeast and yeast hulls) as malolactic nutrients/activators. For each of the 6 modalities we will present the growth of the bacterial cultures, the performance of the MLF, and the modulation of both the metabolome and volatilome of the resulting wines. Finally, we will discuss the potential interest of this new innovation to trigger the MLF and modulate the characteristics of the wines.

Funding Support: Funding: Author contributions: CRediT : SW, AD, EFP, YG

Enhancing Wine Acidity Through
Lactic and Succinic Acid-Producing
Yeast Strains

Mirjam Fischer, Annegret Cantu, Sydney Rogers, Larry Lerno, Hildegarde Heymann and Ben Montpetit*

*University of California Davis, 595 Hilgard Ln, Davis, CA, 95616, benmontpetit@ucdavis.edu

Climate change presents a major challenge for the wine industry because of anticipated changes in grape composition at harvest, which include higher sugar levels (i.e., increased alcohol in wine) and decreased acidity. However, many consumers continue to prefer fresh and vibrant white wine styles, which can be achieved by using novel yeasts that offer a biological solution. For example, Lachancea thermotolerans metabolism produces lactic acid with an associated reduction in alcohol levels. Select Saccharomyces strains also have metabolic outputs that include increased amounts of succinic acid. In this study, a Riesling must (pH 3.5, 22.3 Brix, titratable acidity 4.69 g/L) was fermented using strains of L. thermotolerans and Saccharomyces cerevisiae that were selected for their ability to produce lactic acid or succinic acid. A commercial Saccharomyces yeast (DV10) served as the control. Results demonstrate increased total acidity, ranging from 1.4 to 5.5 g/L, and reduced pH from 0.04 to 0.3 units in L. thermotolerans strains and Saccharomyces strains compared to the control. Furthermore, a decrease in alcohol content was observed, with reductions ranging from 0.13% to 0.67% by volume. Analyses are ongoing, gas chromatography-mass spectrometry for aroma compounds and high-performance liquid chromatography for fermentation by-products (e.g., acid levels), and a descriptive analysis will be conducted with a trained panel to describe the sensory profile of the wines. The results of this bioacidification study will offer insight into using this strategy in place of chemical acidification. Wines with increased acidity levels also serve as blending partners, or as base wines for sparkling wine when higher acidity is needed. It is expected that this approach can help mitigate the effects of climate change, with further research identifying conditions, methods, and new yeasts to expand the application of bioacidification.

Funding Support: Richard M. Kunde Endowed Chair, Flossfeder Scholarship, Horace O. Lanza Scholarship, J. Lohr Fund

Identification of Novel Californian Saccharomyces cerevisiae Strains
with Enological Potential

Sydney Rogers, Mirjam Fischer, Jackson Moore, Annegret Cantu, Larry Lerno, Hildegarde Heymann, Vivien Measday and Ben Montpetit*

*University of California, Davis, 595 Hilgard Ln, Davis, CA, 95616, benmontpetit@ucdavis.edu

California’s wine industry faces challenges due to both climate change and evolving consumer preferences. Rising temperatures, water scarcity, and unpredictable weather affect grape composition, fermentation outcomes, and overall wine quality. Historically, California winemakers have relied on commercial Saccharomyces cerevisiae strains of European origin, limiting region-specific fermentation strategies. However, increasing consumer demand for sustainability and regional authenticity presents an opportunity to explore local yeast populations adapted to California’s climatic conditions. This study examined 24 S. cerevisiae strains isolated from spontaneous Pinot noir fermentations across four AVAs (Anderson Valley, Russian River Valley, Santa Lucia Highlands, and Santa Maria Valley). These strains, classified in either the Wine/European or the novel Pacific West Coast Wine (PWCW) clade, were assessed for commercial winemaking potential through benchtop microfermentations evaluating fermentation kinetics, wine chemistry, and volatile aroma production. Three yeasts, chosen to represent the diversity of these clades, were further tested in production-scale fermentations using Russian River Valley Pinot noir grapes. The resulting wines were analyzed using descriptive analysis, gas chromatography-mass spectrometry with solid-phase microextraction for volatile aromas, high-performance liquid chromatography for organic acids, and a full postfermentation chemistry panel. Results indicate that the three chosen yeasts exhibit distinct volatile aroma profiles, with desirable fermentation kinetics and wine chemistries (ABV, pH, titratable acidity) comparable to commercial strains. Moreover, genomic sequencing data showed that the PWCW yeast clade is defined by a significant mixing of genetic material from California Oak strains and European Wine strains. The exchange of genomic information between these two yeast populations indicates that these yeasts may have been selected to carry traits better suited to California’s climate. Overall, it is expected that these S. cerevisiae strains unique to California could serve as a valuable addition to currently-used European yeasts, supporting wine quality while enhancing sustainability and regional identity.

Funding Support: Richard M. Kunde Endowed Chair, Wine Spectator, American Wine Society Educational Foundation (AWSEF)

Nicholas Mannino | Elizabeth Tomasino | Cole Cerrato | James Osborne*

Strain Selection and Fermentation Timing: Shaping the Chemistry of Pinot noir Wines

Nicholas Mannino, Elizabeth Tomasino, Cole Cerrato and James Osborne*

*Oregon State University, 100 Wiegand Hall, RM 108, Corvallis, OR, 97331, james.osborne@oregonstate.edu

Malolactic fermentation (MLF) is a crucial step in red and some white wine production and is traditionally performed sequentially after alcoholic fermentation (AF). However, concurrent MLF, where Oenococcus oeni or Lactobacillus plantarum is inoculated early in AF, offers potential benefits such as reduced production time. While previous research showed MLF timing can influence Pinot noir aroma and mouthfeel, its impact on chemical properties remains unclear. This study examined the effects of MLF timing (concurrent versus sequential) and ML strain selection on Pinot noir composition. Concurrent MLF did not prolong AF, and it was completed faster than sequential MLF. Among ML strains, O. oeni Berry completed concurrent MLF the fastest, while L. plantarum Prime was the slowest. Acetic acid levels varied, with concurrent MLF by O. oeni Berry producing the highest concentration and L. plantarum Prime the lowest. Post-MLF analysis of color, polymeric pigment, and total polyphenolics showed minimal color differences among O. oeni-fermented wines, regardless of timing. However, sequential MLF with L. plantarum Prime resulted in higher color intensity. Polymeric pigment content was higher in sequential MLF wines, irrespective of ML strain. Additional analysis will be conducted after nine months of aging, including volatile aroma and phenolic profiling. These findings provide insights into the influence of MLF timing and strain selection on Pinot noir chemistry. Understanding these effects can help winemakers optimize MLF management to achieve desired wine styles.

Funding Support: Oregon Wine Research Institute

Inhibition of Pellicle Formation by
a Solvent-Extracted Fraction from
Non-Pellicle Wine

Fumie Watanabe-Saito,* Rina Goto, Shunya Muramatsu, Youji Nakagawa, Munekazu Kishimoto, Masashi Hisamoto and Tohru Okuda

*The Institute of Enology and Viticulture, Graduate Faculty of Interdisciplinary Research, University of Yamanashi, 13-1, Kitashin-1-Chome, Kofu, Yamanashi 400-0005, Japan, fumies@yamanashi.ac.jp

Pellicle-forming yeasts (hereinafter, pellicle yeasts) can develop a pellicle during winemaking, leading to unpleasant odors and wine quality deterioration. In this study, we inoculated and cultivated pellicle yeasts (Saccharomyces cerevisiae strain YFY-1) in various commercial wines. Some wines developed a pellicle (pellicle wine), whereas others did not (non-pellicle wine). A solvent-extracted fraction from non-pellicle wine exhibited pellicle inhibitory activity. To elucidate the underlying mechanism, we analyzed the behavior of pellicle yeasts in media with and without the inhibitory fraction. In media without the inhibitory fraction, the yeast population segregated into settled and floating cells. The total number of settled cells remained stable for 7 days, while their viable cell count declined from 69% (day 1) to 27% (day 7). The total number of floating cells increased until day 5 and then plateaued, with their viable cell count rising from 24% (day 1) to 72% (day 3). In contrast, in media containing the inhibitory fraction, the total number of floating cells remained largely unchanged over 7 days. The viable cell count in floating cells decreased from 37% (3 hr postinoculation) to 15% (day 2) and remained at 15% thereafter. These results suggest that pellicle yeasts can float and persist at the air-liquid interface in non-pellicle wine while the inhibitory fraction suppresses their activity, preventing pellicle formation. This finding offers new insights into strategies for mitigating pellicle contamination in winemaking.

Funding Support: JSPS KAKENHI Grant Number 22K05539

Masashi Hisamoto* | Yumeko Ota | Fumie Watanabe-Saito | Tohru Okuda

Conversion of Diglucoside Anthocyanins to Polymeric Pigments and Their Influence on Wine

Masashi Hisamoto,* Yumeko Ota, Fumie Watanabe-Saito and Tohru Okuda

*The Institute of Enology and Viticulture, University of Yamanashi, 1-13-1 Kitashin, Kofu, Yamanashi 400-0005, Japan, hisamoto@yamanashi.ac.jp

The instability of anthocyanins in wines is well known. During aging, anthocyanins react with acetaldehyde and flavan-3-ols, forming highly stable macromolecular pigments. Vitis vinifera, primarily cultivated for wine production, contains monoglucoside anthocyanins, while non-V. vinifera species contain diglucoside anthocyanins. Vitis coignetiae and its interspecific hybrids are known for having high diglucoside anthocyanin content. However, empirical evidence suggests they are not prone to color changes in wine. Using malvidin 3-O-glucoside (Mv3G), malvidin 3,5-O-diglucoside (Mv3,5DG), and malvidin 3-(6-O–p-coumaroylglucoside)-5-glucoside (Mv3,5DG-pCoA), we investigated the characteristics of anthocyanin hydration, reactivity with sulfites, and polymerization to understand their influence on wine. Mv3,5DG-pCoA exhibited exceptional stability under model wine conditions, suggesting its potential contribution to the black-purple coloration in wine. Through forced polymerization, we found that adding acetaldehyde promoted consumption of only Mv3G and not the ethyl cross-linking polymerization of diglucoside anthocyanins. Furthermore, adding catechin resulted in the formation of an ethyl bridge between each anthocyanin and catechin. The polymerization rate constants indicated that Mv3G had the highest reaction rate and Mv3,5DG-pCoA polymerization proceeded more rapidly than Mv3,5DG. We also assessed the contribution of anthocyanins to wine color by measuring high molecular weight pigments in commercial wines made from wild grapes and V. vinifera. Our analysis revealed that V. coignetiae and its hybrids had minimal levels of large polymeric pigments. In contrast, the levels of small polymeric pigments were comparable to those observed in Merlot.

Funding Support: This work was supported by JSPS KAKENHI Grant Number JP20K05874.

Takuro IWAYA | Kanako YANAGISAWA | Kanako SASAKI*

A New Method to Detect Fungicide Resistance in Grape Downy Mildew Using Aseptically Cultured Plants

Takuro IWAYA, Kanako YANAGISAWA and Kanako SASAKI*

*Institute for Future Beverages, Kirin Holdings Company, Limited , 26-1-12-12, Muraoka-Higashi 2-chome, Fujisawa, Kanagawa 251-8555, Japan, Kanako_Sasaki@kirin.co.jp

Grape downy mildew caused by Plasmopara viticola is one of the most common and significant diseases affecting grapevines worldwide. Various fungicides are commonly used to control this pathogen in the vineyard. However, resistance to many of the most effective fungicides has emerged and spread within pathogen populations, compromising disease control. Therefore, identifying resistance and its prevalence is necessary to determine strategies for resistance management. Several methods exist to detect resistance to certain fungicides, such as the leaf-disc bioassay, PCR-restriction fragment length polymorphism (RFLP), and in vitro mycelium growth test on fungicide-amended media. However, these methods have disadvantages. For instance, maintaining plants in a disease-free condition for the leaf-disc bioassay is quite challenging, the mutation implicated in fungicide resistance must be identified for PCR-RFLP, and obligate biotrophs, including P. viticola, cannot be evaluated using fungicide-amended artificial media. To address these disadvantages, we developed a new method to detect resistance to certain fungicides through a two-step approach. First, we developed a method to cultivate P. viticola using aseptically-cultured grapevines. This method allows stable maintenance of P. viticola and provides a continuous supply for various assays. Second, we developed a way to detect resistance of P. viticola to quinone outside inhibiting fungicides using aseptically-cultured plants. This method can also be applied to other fungicides. Expanding the range of diseases and fungicides covered by this method is expected to further optimize disease management.

Funding Support: Kirin Holdings Company, Limited

Nick Wendrick | Andrew MacIntosh | Katherine Thompson-Witrick*

Influence of Packaging Material
on the Properties of Carbonated
Blueberry Wine Under Accelerated
Storage Conditions

Nick Wendrick, Andrew MacIntosh and Katherine Thompson-Witrick*

*University of Florida, 520 Newell Dr., Gainesville, FL, 32611, kthompsonwitrick@ufl.edu

Wine is a complex beverage containing an array of flavor compounds generally derived from volatile organic compounds (VOCs) and basic tastes attributed to sugars (sweetness), organic acid (sourness), and polyphenols (bitterness/astringency). These components may interact with the packaging material, significantly affecting the consumer experience. Alternative packaging has been gaining popularity with consumers due to portability, convenience, and recyclability. This project investigated the chemical changes in carbonated blueberry wine packaged in aluminum cans, polyethylene terephthalate (PET), and glass bottles at accelerated temperatures (35°C) for 60 days to parse the capacities of alternative packaging. Blueberry wine was packaged in cans and bottles, and the pH, titratable acidity (TA), free and total sulfites, sugar, alcohol, color, and flavor compounds were assessed. Several analyses showed no significant difference (p < 0.05), including TA, pH, sugar, and alcohol. The primary VOC classes identified included alcohols, acids, aldehydes, esters, and terpenes, with a starting concentration of 64.5 mg/L. The VOC analysis showed cans (70.8 mg/L) outperforming PET (44.4 mg/L) and glass bottles (58.9 mg/L), demonstrating suboptimal flavor stability. Moreover, there was a significant difference in spectrophotometric color intensity over 60 days, with a starting value of 1.78 AU for all packages; the means of the aluminum cans, PET bottles, and glass bottles were 1.67, 2.09, and 1.84 AU, respectively. The color hue was significantly lower for cans than for both bottle types, indicating better color retention. Additionally, free (starting 46.9 mg/L) and total (starting 140 mg/L) sulfites significantly differed after 60 days, as cans outperformed glass and PET bottles in both analyses. These research findings suggest that PET and glass bottles are not the ideal packaging types for carbonated blueberry wine. However, cans exhibit minimal chemical changes over time, supporting cans as a viable alternative package.

Funding Support: Florida Department of Agriculture and Consumer Services

Abraham Ahumada* | Dr. Shunping Ding | Skye Reading

Screening for Fungicide Resistance
in Botrytis cinerea from California Central Coast Vineyards

Abraham Ahumada,* Dr. Shunping Ding and Skye Reading

*CalPoly San Luis Obispo, 8125 Amapoa Ave, Unit F, Atascadero, CA, 93422, abahumada@yahoo.com

Botrytis cinerea is a necrotrophic fungal pathogen that causes grey mold on a large spectrum of fruit. It is responsible for bunch rot in grapes and is managed by multiple fungicide applications throughout the growing season. Repetitive fungicide applications lead to accumulation of fungicide resistance in pathogen populations. Resistance monitoring is important to preserve fungicide efficacy. In this study, an assessment of resistance levels in B. cinerea isolates was conducted. Isolates were collected from four vineyards on the central coast of California (Paso Robles, Arroyo Grande, San Luis Obispo, and Greenfield). Each of the 36 isolates collected was exposed to two concentrations of an active fungicide ingredient (a high and a low concentration), as well as a control treatment (no fungicide). Screening for resistance has been completed for fungicide active ingredients fenhexamid (FRAC 17) and cyprodinil (FRAC 9), with additional fungicide classes to follow. Resistance was assessed by the level of inhibition of mycelial growth. For fenhexamid, 28% of isolates were moderately sensitive, while 72% were highly sensitive. In cyprodinil, 3% of isolates were highly sensitive, 61% were moderately sensitive, 33% were moderately resistant, and 3% were highly resistant. The findings from this study will contribute to ongoing resistance monitoring efforts and provide information on fungicide management strategies to optimize the control of Botrytis bunch rot in California vineyards.

Funding Support: Cal Poly San Luis Obispo

Arpa Boghozian* | Reddy Kishorekumar | Mysore Sudarshana | Ben Montpetit | Anita Oberholster

Impact of Grapevine Red Blotch Virus Infection on Grape Cell Wall Ripening Enzymes Over Two Growing Seasons

Arpa Boghozian,* Reddy Kishorekumar, Mysore Sudarshana, Ben Montpetit and Anita Oberholster

*University of California, Davis, 595 Hilgard Lane, Davis, CA, 95616, amboghozian@ucdavis.edu

Grapevine red blotch virus (GRBV), a member of the Geminiviridae family vectored by the three-corned alfalfa treehopper, Spissistilus festinus, causes delayed grape ripening. Fruit softening results from cell wall enzymatic hydrolysis and pectic polysaccharide changes including transglycosylation, solubilization, and depolymerization regulated by pectin methylesterase (PME), polygalacturonase (PG), pectate lyase (PL), and ß-galactosidase. These enzymes are responsible for pectin depolymerization and solubilization, initiating the fruit ripening process. In our recent studies, it was observed that there is an increase in the pectin fraction in fruit from GRBV-infected grapevines during ripening. In this study, we investigated GRBV’s effect on enzymes related to pectic depolymerization and solubilization using fruit from virus-infected (GRBV(+)) and non-infected (GRBV(-)) vines from a commercial vineyard in Paso Robles, CA in the 2021 and 2022 growing seasons. Grapes were harvested at four time points: preveraison, veraison, postveraison, and harvest. Biochemical analyses involved measuring ß-galactosidase activity in relation to total protein content. A Student t-test compared GRBV(+) to GRBV(-) at each ripening time point within each year. In the 2021 season at veraison, GRBV(+) and GRBV(-) grapes were significantly different in ß-galactosidase activity. In the 2022 season at preveraison and postveraison, GRBV(+) and GRBV(-) grapes were also significantly different. These data indicate that there are differences in ß-galactosidase activity between GRBV(+) and GRBV(-) grapes. The differences in activity between the 2021 and 2022 seasons could be attributed to the environmental impacts on enzymatic regulation. Further investigation into these differences, and other enzyme activities such as PME, PG, and PL, are needed to understand how GRBV infection affects enzymes related to pectic depolymerization and solubilization across the growing season. It is expected that understanding the viral impact on grape enzyme activity and its correlation with berry softening will help determine mitigation strategies for the winemaking industry.

Funding Support: CDFA-PD/GWSS Board, American Society of Enology and Viticulture Traditional Scholarship, UC Davis Department of Viticulture and Enology Scholarship, NIFA Specialty Crops Research Initiative

Enhancing Grapevine Red Blotch
Virus Detection: Multi-Vineyard
Model Improvement and Deep
Learning Integration

Eve Laroche-Pinel, Vincenzo Cianciola, Alessandro De Rosa, Adan Solis, Marco Saldivar, Marc Fuchs and Luca Brillante*

*Department of Viticulture and Enology, California State University Fresno, 2360 E Barstow Ave, Fresno, CA, 93740, lucabrillante@csufresno.edu

Grapevine red blotch virus (GRBV) is a significant viral disease affecting vineyards, reducing fruit quality by altering sugar accumulation and phenolic composition. Accurate and timely identification is crucial for disease management and vineyard sustainability. To improve the accuracy and reliability of our previous GRBV prediction model, we expanded our data set in 2024 by incorporating data from three additional vineyards alongside our primary site. Approximately 30 vines per vineyard were tested using PCR, while drone-based VIS/NIR imaging was conducted in late September. The updated data set, consisting of 669 vines with a 60.1% infection rate, was used to retrain the model. Following recalibration, the improved model achieved a test accuracy of 78.1%, with 75% accuracy in identifying non-infected vines and 81% accuracy in detecting GRBV-infected vines. Prediction maps were generated for each vineyard and presented to growers at the end of 2024. Comparisons between model predictions, PCR results, and growers’ field observations validated the maps. One grower, actively mapping GRBV in his vineyard, found strong agreement between his independent screening and our prediction map, reinforcing the model’s effectiveness. New efforts also focused on improving prediction accuracy through deep learning, particularly convolutional neural networks (CNNs), which have demonstrated strong performance in vineyard disease detection. By leveraging CNNs’ ability to analyze complex spectral patterns, we aim to refine disease classification and enhance spectral indicators of GRBV. These advancements will contribute to practical, data-driven solutions for early disease detection and improved vineyard management strategies.

Funding Support: CDFA Pierce Disease and Glassy Winged Sharp Shooter Board; California State University Agricultural Research Institute; F3 Future of Food Innovative Initiative; Bronco Wine Co. Chair in Viticulture

Paul Cooper*

Role of the Stomatogastric Nervous System in Controlling Feeding in Hemipteran Pests of Grapevines

Paul Cooper*

*Research School of Biology, Australian National University, EE, Bld 46, Research School of Biology, The Australian National University, Canberra/A.C.T./2601, Australia, paul.cooper@anu.edu.au

Several insects feed on grapevines, leading to plant damage, decreased yield, and potential disease spread. Scale insects, mealy bugs, and leafhoppers are all members of the Hemiptera, a taxon that feeds by inserting their stylet (modified mouthparts) into the leaves and feeding on various parts of the plant. The control of feeding is regulated by the stomatogastric nervous system controlling the muscles of the head. Our work examined the muscle structure using traditional histological techniques combined with modern three-dimensional examination using microcomputer tomography. By including immunohistochemistry to trace the nerves that innervate muscles within the head and around the foregut (precibarium and cibarium) along with the 3D computer tomography, the control of the muscles that generate the pressures necessary to extract the plant nutrients may show how these insects feed at the cellular level. It is hoped that this work will indicate novel ways that lead to limiting insect damage using novel methods. As our previous work has shown how some grape cultivars are resistant to scale insect outbreaks, it is hoped that we can understand how the chemicals that are involved with this resistance may lead to a reduction of feeding as a result of interfering with the muscular movements necessary for feeding.

Funding Support: Research School of Biology, Australian National University

Tanner Dollar | Francisco Ochoa-Corona | Nathan Walker | Stephen Marek | Mustafa Jibrin*

Survey and Characterization
of Grape Black Rot in Oklahoma

Tanner Dollar, Francisco Ochoa-Corona, Nathan Walker, Stephen Marek and Mustafa Jibrin*

*Oklahoma State University, 127 Noble Research Center, Stillwater, OK, 74075, Mustafa.Jibrin@okstate.edu

Locally crafted Oklahoma grape products have been the center of focus and development as the state continues to grow its interest and production in Oklahoma-grown grapes. Grape black rot, caused by the fungus Phyllostica ampelicida, is considered one of the most economically impactful diseases affecting grapevines in Oklahoma. However, there is a paucity of information on the epidemiology, population, and fungicide sensitivity of P. ampelicida in Oklahoma. The objectives of this study were to survey and characterize the grape black rot disease in Oklahoma. A survey of vineyards in eight counties was conducted in 2024, during the dormant and active growing stages. Samples of leaves, mature berries, mummies, and canes were collected in sterile sampling bags, placed on ice, and taken to the laboratory for further processing. Pathogens were isolated from excised areas surrounding diseased lesions on collected samples. Excisions were washed with sterile tap water, placed in 1% NaClO for 1 min, and transferred to acidified potato dextrose agar (APDA). A sterile loop was used to transfer each unique fungal growth to new PDA. More than 2000 fungal isolates have been recovered thus far from different grapevine varieties. Agar plugs of each isolate were stored in 30% glycerol and kept at -80°C. DNA was extracted from mycelial growth on PDA and processed using PCR with primers targeting the ITS region. Purified PCR products were sequenced at the OSU DNA Core Facility, Stillwater, using the Sanger sequencing method. Results from BLAST search identified isolates that are P. ampelicida and other fungi. Additional sequencing based on the β-tubulin, Calmodulin, TEF1, GDPH, and ACT primers are ongoing and will be presented. Our results are important for identification of the species causing grape black rot in Oklahoma and forming a basis for additional studies on population structure, epidemiology, and fungicide screening.

Funding Support: Oklahoma Department of Agriculture, Food, and Forestry, Oklahoma Agricultural Experimental Station

Jesse Stevens | Michelle Moyer* | Maria Mireles

Integrating UV-C and Canopy Management for Grape Powdery
Mildew Control

Jesse Stevens, Michelle Moyer* and Maria Mireles

*Washington State University, 24106 North Bunn Road, Prosser, WA, 99350, michelle.moyer@wsu.edu

The germicidal effects of UV-C light (254 nm) have been used as a method of grape powdery mildew (Erysiphe necator) suppression in multiple crops, including grapevines (Vitis vinifera). The use of UV-C light in Washington vineyards may help mitigate fungicide resistance by introducing new methods to expand IPM strategies for grape diseases. However, since the application of UV-C cannot be adjusted like traditional sprays (i.e., changes in water or air volume), information is needed on how grapevine canopy management influences the effectiveness of UV-C light applications. In 2023 and 2024, we conducted a study on the effectiveness of hybrid fungicide/ UV-C regimes and canopy management techniques on powdery mildew management. The study included integrated once and twice a week UV-C applications (200 J/m²) during the powdery mildew “critical window” (start of bloom to 4 wk post full-bloom), an unsprayed control, and a sprayed grower control. Within each of these management regimes, we also nested and compared disease control between canopy management strategies, including shoot thinning, shoot thinning + early fruit zone leaf removal, and a no canopy management control. In both years, canopy management did not help nor hinder disease severity in an already effective mildew management strategy, including both UV-C regimes and the grower control (p = 0.75). Canopy management did, however, have a significant effect in reducing mildew severity in the high-disease pressure unsprayed controls (p < 0.0001). Yield and fruit quality differences were primarily due to differences in fungicide treatments, not canopy management. This information re-verifies the usefulness of UV-C light as a method of grape powdery mildew control and highlights the effectiveness of canopy management in high-disease pressure situations.

Funding Support: Washington State Grape and Wine Research Program, Washington State University Auction of Washington Wines, Washington State wine grape growers and winery through the Washington State wine commission, Northwest Center for Small Fruits Research

Benny Ordonez | Lance Cadle-Davidson | Zachary Dashner | Andy Walker | Summaira Riaz*

Global Genetic Diversity
and Population Structure of
Grapevine Powdery Mildew

Benny Ordonez, Lance Cadle-Davidson, Zachary Dashner, Andy Walker and Summaira Riaz*

*USDA-ARS, 9611 S Riverbend Ave, Parlier, CA, 93648, summaira.riaz@usda.gov

Grapevine powdery mildew (PM), caused by Erysiphe necator, is one of the most destructive diseases in viticulture, threatening global wine, table, and raisin grape production. While previous studies provide regional and global assessments of its genetic diversity, key questions remain about its population structure, introduction history, and adaptation across viticulture regions. This study expands on prior work with a more comprehensive data set of 410 samples from North and South America, Europe, and Australia, leveraging 20 microsatellite markers to refine our understanding of PM diversity at global level. Our findings verified a distinct genetic separation between the eastern and western United States, reinforcing the hypothesis of an eastern North American origin. We also uncovered greater genetic diversity in California and Oregon than reported previously, suggesting multiple introduction events or increased recombination within the western U.S. Furthermore, we provide the first genetic characterization of Australian E. necator populations, identifying a unique cluster shaped by long-term isolation and a distinct introduction history. Our results suggest that evolving E. necator populations may affect the effectiveness of disease management strategies, particularly under climate change and fungicide selection pressure. This study enhances our understanding of E. necator population dynamics, providing valuable insights for the development of region-specific disease control strategies and sustainable viticultural practices.

Funding Support: American Vineyard Foundation

Integrative Multi-Omics Analysis of GRBV Effects on Grapevine: Unraveling Temporal, Genetic, and Metabolic Dynamics

Prem Singh, Hazel Scully, Kishorekumar Reddy, Arpa Boghozian, Cristina Medina-Plaza, Anita Oberholster and Mysore Sudarshana*

*USDA-ARS, Department of Plant Pathology, 380 Hutchison Hall, 3rd Floor, Davis, CA, 95616, mysore.sudarshana@usda.gov

The grapevine industry is significantly threatened by grapevine red blotch virus (GRBV), which impairs fruit ripening, ultimately affecting wine quality. While previous studies focused on seasonal patterns of viral dynamics, the current research expands on this by employing a multi-omics approach. Specifically, integration of transcriptomics and metabolomics sheds light on how GRBV affects gene expression, metabolic pathways, and fruit composition at different maturity stages of grapevine development. In the present study, we evaluated GRBV-infected Vitis vinifera L. Merlot grapevines across four maturity stages (preveraison, veraison, postveraison, and harvest) over multiple years of infection in a Central Coast vineyard. Viral copy numbers were quantified using digital PCR, revealing significant temporal variations in 2021, but less pronounced differences in 2022 due to environmental stressors such as heat spikes exceeding 30°C. Transcriptomic analysis revealed changes in gene expression at each maturity stage, focusing on transcription factors, defense-related proteins (PR proteins), and hormone regulation pathways. Simultaneously, metabolomic profiling using SPME-GC-MS and UHPLC-QTOF-MS identified key volatile and non-volatile metabolites associated with viral infection and altered ripening processes. Preliminary findings suggest a strong correlation between GRBV infection and disrupted carbon translocation, with notable changes in the phenylpropanoid pathway and cell wall metabolism that may affect phenolic extractability during winemaking. The integration of transcriptomics and metabolomics data provides a comprehensive view of the effect of GRBV on grapevine physiology and berry metabolism, offering new insights into potential mitigation strategies to reduce the virus’s impact on grape and wine quality.

Funding Support: CDFA-PD/GWSS USDA-NIFA-SCRI

Dallas Parnigoni | Federico Casassa* | Sean Kuster | Bob Coleman | James Nelson

Effects of Air and Nitrogen Gas Mixing During Alcoholic Fermentation on the Oxidation-Reduction Potential and Chemical Outcomes of Syrah Wines

Dallas Parnigoni, Federico Casassa,* Sean Kuster, Bob Coleman and James Nelson

*Wine and Viticulture Department- Cal Poly San Luis Obispo, 1 Grand Avenue, San Luis Obispo, CA, 93407, lcasassa@calpoly.edu

Syrah wines were produced using three cap management protocols consisting of gas mixing with nitrogen (N₂) gas and air, with contrasting bubble sizes during alcoholic fermentation. These were: air injections through 2 µm pore size sinter elements (AirMixSinter, two 1 hr additions/day), air injections through 3 mm tubing (AirMixTubing, two 1 hr additions/day), and simultaneous air injections through a sinter element and N₂ gas injections through 3 mm tubing (MixGas, two 1 hr additions/day). Oxidation-reduction potential (ORP) was monitored in all treatments throughout alcoholic fermentation. AirMixSinter wines exhibited the highest mean ORP (105 mV), followed by MixGas (62 mV) and AirMixTubing (28 mV). At day 6 postcrushing, reductions in anthocyanins of 20% (AirMixSinter) and 16% (MixGas), reductions in tannins of 17% (AirMixSinter, MixGas), and reductions in total phenolics of 14% (AirMixSinter) and 12% (MixGas), compared to AirMixTubing wines were observed, which were maintained up to pressing. At pressing, AirMixSinter wines showed 22% reductions in flavonols, but insignificant reductions in flavan-3-ols when compared to AirMixTubing wines, suggesting preferential oxidation pathways. There were no differences between MixGas and AirMixSinter wines in flavonols or flavan-3-ols at pressing. While AirMixSinter and AirMixTubing wines showed no significant difference in total volatiles, MixGas wines showed the fewest concentrations of volatiles at pressing, with 18% and 20% reductions when compared to AirMixSinter and AirMixTubing wines, respectively, suggesting greater volatile purging with simultaneous N₂ gas injections in MixGas wines, which effectively had double the volume of gas injected compared to the other treatments. Varying air bubble size had marked effects on ORP response and phenolic losses, despite equal volumes and flow rates, while supplementary N₂ mixing had negligible effects on phenolic extraction under the given size and temperature conditions.

Funding Support: Couch Family Wines

Hyperspectral Phenolics: Exploring the Covariation between Leaf and Berry Reflectance and Berry Chemistry

Alexandra Basquette,* Chris Wong, Jessie Lyons, James Campbell, Elisabeth Forrestel, Troy Magney and Fallon Ely

*University of California Davis, 392 Old Davis Rd, Davis, CA, 95616, azbasquette@ucdavis.edu

To track grape chemistry development across the growing season and ultimately determine harvest timelines, berries must be sampled regularly and analyzed across broad spatial and temporal scales. To reduce reliance on this time-consuming method, proximal sensing techniques have been employed to determine potential covariation between plant reflectance signatures and chemical indicators of berry ripeness and phenolics. This study relates both foliar and berry reflectance data to primary (titratable acidity [TA], total soluble solids [TSS], pH) and secondary (anthocyanin, flavonols, tannins) berry chemistry metrics. Developing reliable means to predict grape phenolics benefits the industry, as current methods require much time, cost, and expertise to measure accurately. Over the 2023 to 2024 growing seasons at the Robert Mondavi Institute Vineyards at UC Davis, six sampling time points were selected between version and harvest for the collection of berry samples and spectral reflectance data on 17 red grape varieties across 42 vines. One hundred forty berries were sampled per vine, with 60 being processed immediately for primary chemistry metrics (TA, pH, and TSS) and the remainder being frozen for later phenolic analysis. A Spectra Vista Corporation (SVC) spectroradiometer with a range of 400 to 2500 nm was used to take three foliar scans and three scans of collected berry samples for all study vines on the same date of berry sampling. Phenolic data was processed using high-performance liquid chromatography after undergoing acetone extraction. These data will be analyzed via a partial least squares regression model to identify the spectral bands or regions that best predict berry chemistry. Preliminary results indicate success in predicting tartaric acid data across the growing season (Wong et al. 2025). This study builds on previous work by including phenolic chemistry and berry spectra, as well as increasing postveraison measurements across multiple growing seasons.

Funding Support: USDA NIFA Specialty Crop Research Initiative (SCRI) for “Assessment and Management of Risk Associated with Wildfire Smoke Exposure of Grapes in the Vineyard” (project award no. 2021-51181-35862)

Patricia Skinkis* | Ainsley McCollum | Elizabeth Tomasino | James Osborne

Wine Technical Tasting Reveals No Yield-Specific Sensory Relationship
in Pinot noir Crop Load Trial

Patricia Skinkis,* Ainsley McCollum, Elizabeth Tomasino and James Osborne

*Oregon State University, 2750 SW Campus Way, 4017 Ag & Life Sci Bldg, Corvallis, OR, 97331, patricia.skinkis@oregonstate.edu

Low yields have been synonymous with quality in premium wine production, and this is often achieved through thinning clusters to reach target yields. Premium Oregon Pinot noir is known for quality and vineyards have been heavily cluster-thinned to achieve low target yields for decades. However, producers began to question the validity of this practice for fruit and wine quality, especially with raising production costs. To address this, a 10-yr project was conducted in more than 20 Pinot noir vineyards in Oregon’s Willamette Valley from 2012 to 2021. Wines produced from replicated vineyard trials at collaborator vineyards were evaluated in a double-blind technical tasting in 2019. This tasting event included winemakers, enologists, and other vineyard and winery staff in horizontal and vertical tastings of 63 wines from 2014 to 2017. A total of 58 participants were involved in the vertical tasting (three vintages by one producer). Participants were then split into three groups for horizontal tastings of multiple producers by vintage, focusing on 2014, 2015 and 2016. Quantitative and qualitative results by individual and group discussion were analyzed from all tastings. Results show that there was no clear preference based on crop yield and the most-preferred wines were not always the lowest yield. There was no clear trend of lower yield resulting in distinctly better color, aroma, taste, or mouthfeel. However, mouthfeel was the most common reason for wine preference. This work shows that yield management for quality is not straightforward, as seasonal weather conditions, vineyard characteristics, and winemaking team have the greatest impacts on wine sensory results.

Funding Support: Oregon Wine Board, OSU Viticulture Extension, and Erath Family Foundation Undergraduate Scholars Program

Mara Anton | Camilla Sartori | Amanda Dupas De Matos | Elizabeth Tomasino*

Evaluating the Sensory Impacts of Fermentation Techniques on Tropical Fruit Aroma in Chardonnay Wines

Mara Anton, Camilla Sartori, Amanda Dupas De Matos and Elizabeth Tomasino*

*Oregon State University, 100 Wiegand Hall, Corvallis, OR, 97331, elizabeth.tomasino@oregonstate.edu

Tropical fruit aromas in white wine have been identified as positive sensory qualities by wine consumers. This research expands upon previous work by investigating how a fermentation temperature gradient and cold soak techniques affect aroma development in Chardonnay wine. This work continues on from the first year of techniques to determine if these treatments result in similar sensory qualities for an additional vintage. Chardonnay grapes from the 2024 vintage in the Willamette Valley, Oregon were used. Five treatments were used: (1) control (no skin contact) with fermentation at 13°C, (2) control with fermentation at 20°C, (3) 24 hr skin contact with fermentation at 20°C, (4) Control (no skin contact) with fermentation at 20°C for 5 days, then at 13°C thereafter, (5) 18 hr skin contact with fermentation at 20°C for 5 days, then at 13°C thereafter. Sensory evaluations were conducted using a consumer panel to include overall acceptance, emotional response, and a check-all-that-apply (CATA) characterization for aroma description that contained 19 aroma target words. Samples from each treatment were taken at the time of sensory evaluation to identify and quantify aroma compounds present that have previously been identified as contributors to the target aromas evaluated in the CATA characterization. These results will be compared to sensory evaluation measurements to provide both a chemical and sensory profile of the six treatments, and to similar results from a previous vintage.

Funding Support: Oregon Wine Research Institute and Erath Family Foundation Undergraduate Scholars Program

Marnelle Salie* | Runze Cliff Yu | Qun Sun | Keith Striegler | Sonet Van Zyl

Effect of Training System and Pruning Severity on Teroldego Grapevines in the San Joaquin Valley, California

Marnelle Salie,* Runze Cliff Yu, Qun Sun, Keith Striegler and Sonet Van Zyl

*Gallo, 600 Yosemite Blvd., Modesto, CA, 95354 & Department of Viticulture and Enology, California State University Fresno, 2360 E Barstow Ave, Fresno, CA, 93740, marnelle.salie@ejgallo.com

Proper training and pruning systems are crucial to winegrape production. These viticultural practices affect vine physiology, yield, fruit composition, and wine quality. However, for the Vitis vinifera variety Teroldego, studies have not been conducted on the appropriate training and pruning method for the San Joaquin Valley of California. Teroldego is primarily used for red blends due to its high anthocyanins and mild tannins. Traditionally, it is head-trained and cane-pruned, a very expensive way to farm winegrapes due to the rising cost of hand labor. In this trial, Teroldego was evaluated using two training/pruning systems: head-trained/cane-pruned and cordon-trained/spur-pruned from 2021 to 2023 on a quadrilateral trellis. Each training system treatment received three levels of pruning severity: five, 10, and 15 retained nodes per 0.45 kg of pruning weight to compare both methods equally through balanced pruning. Yield, vegetative growth, pruning components, fruit composition, wine quality, and economic performance were evaluated. Yield and yield component results showed significant vintage interactions, but pruning severity had the greatest influence on cluster number per vine, leading to greater yields in treatments with more retained nodes. Fruit composition differed among treatments due to crop load, but all treatments achieved target maturity and were within industry quality standards. Shoot density was greater with more retained nodes; however, no consequences were observed in the fruit or wine. For growers, switching from head-trained/cane-pruned to cordon-trained/spur-pruned systems allows more vineyard mechanization and ~76% savings on pruning costs. This trial shows an opportunity for Teroldego to be grown more economically in the San Joaquin Valley by lowering operational costs while maintaining viable yields and equivalent quality.

Funding Support: Gallo

Shijian Zhuang* | Karl Lund | Matthew Fidelibus | Philippe Rolshausen

Evaluation of Seven Rootstocks Under Drought and Saline Condition for Wine Varieties in the Southern San Joaquin Valley

Shijian Zhuang,* Karl Lund, Matthew Fidelibus and Philippe Rolshausen

*University of California Cooperative Extension at Fresno County, Suite 210-B, 550 E Shaw Ave, Fresno, CA, 93710, gzhuang@ucanr.edu

Soil salinity and saline groundwater are primary challenges for viticulture in the western San Joaquin Valley, which accounts for 60% of winegrape production in California. Great uncertainty regarding availability of surface water and continuing drought have jeopardized sustainable grape production in this region. Unpredictable winter precipitation and limited outsourced water for leaching have made the saline condition more severe. Boron is the main concern of toxicity for this region. A three-way (two varietals × two irrigation regimes × seven rootstocks) split-block field trial was established in 2020 at the UC Westside Research and Extension Center near Five Points. Two varietals (Barbera and Colombard) and seven rootstocks (1103P, 140 Ruggeri, Ramsey, GRN3, Freedom, RS3, and own root) were replicated four times with seven vines designated as an experimental unit. Two irrigation regimes were used: 40% ET_c and 80% ET_c from budbreak to harvest. Freedom had the most accumulated yield and the largest canopy size, measured by pruning weight, and less B in the plant tissues. Rootstocks mainly affected berry pH and titratable acidity, while berry total soluble solids were affected more by yield. Water deficit caused yield reduction by reducing berry weight, while also reducing pruning weight. No interaction of rootstock and irrigation regimes was found. The two-year results highlighted the challenges of growing grape in such saline conditions and the importance of selecting the optimum rootstock for better vine growth and crop production.

Funding Support: CA Grape Rootstock Commission

Riley Hibbard | Brent Sams* | Mahyar Aboutalebi | Luis Sanchez | Nick Dokoozlian

Understanding Spatial Variability of Vine Yield Components in Sonoma County Cabernet Sauvignon Vineyards

Riley Hibbard, Brent Sams,* Mahyar Aboutalebi, Luis Sanchez and Nick Dokoozlian

*GALLO, 1541 Cummins Dr, Modesto, CA, 95358, brent.sams@ejgallo.com

Vineyard yield has been shown to vary spatially by 10x in a single vineyard, but individual yield components (berry weight, clusters per vine, etc.) have not been widely studied spatially at the commercial scale. These yield components are extremely important as it is imperative to have accurate counts and weights for good estimates of final yield. In the highly manipulated vineyards of Sonoma County, California, clusters per vine may vary less than in mechanized vineyards of higher-production regions like the Central Valley, but differences in yield are still present. In 2024, yield components were collected from five Cabernet Sauvignon vineyards in northern Sonoma County at four phenological stages: bloom (cluster count only), fruit set, veraison, and commercial harvest. Plots were distributed according to a histogram analysis of a normalized difference vegetation index derived from a Sentinel 2 image from mid-June of the 2023 season to ensure data were captured across different canopy sizes (high, medium, low). Cluster counts were found to be relatively stable across vigor classes and time points, but berry weights, berry counts, and rachis weights varied by canopy size. Berry size increased as the season progressed in all vigor classes, but differed by canopy size, with the rate of increase slower in low vigor canopies. Further work will focus on identifying causes of different rates of berry growth by canopy vigor.

Funding Support: GALLO

Strategies to Mitigate Heat Stress
and Delay Berry Ripening in Grape Production Amid Climate Change

Guadalupe Partida, Luca Pallotti, Vincenzo Cianciola, Alessandro De Rosa, Marco Saldivar, Xavier Rideout, William Whalen and Luca Brillante*

*Department of Viticulture and Enology, California State University Fresno, 2360 E Barstow Ave, Fresno, CA, 93740, lucabrillante@csufresno.edu

Global warming increasingly threatens grape production in regions like California’s Central Valley. Late-season practices aimed at reducing photosynthetic efficiency may enhance vine resilience and delay ripening. Over three years, this study compared an untreated control (C) with applications of pinolene (P) and diatomaceous earth (D), as well as a novel shoot twisting (T) treatment designed to mimic the benefits of topping while preventing excessive cluster exposure. Measurements of leaf area, light interception, midday stem water potential, and gas exchange were collected throughout each growing season. Berry ripening progression and grape production at harvest were also assessed. Shoot twisting led to desiccation of the upper portion of the shoot, reducing leaf area while maintaining low irradiance in the fruiting zone. Stem water potential data indicated that D, and particularly T, alleviated stress conditions, while P negatively affected vine water status. D significantly influenced gas exchange, increasing transpiration and stomatal conductance, resulting in a trend toward improved water use efficiency. Additionally, D and T treatments promoted higher berry weights in the first half of the season, likely due to improved water status, while P had the opposite effect. All treatments altered berry ripening dynamics, leading to higher titratable acidity and lower must pH without reducing yield. These findings demonstrate that modifying traditional, easily mechanizable practices—such as topping—and incorporating new products like diatomaceous earth are effective strategies for mitigating summer heat stress and delaying ripening in hot, arid regions.

Funding Support: Bronco Wine Co. Chair in Viticulture

Physiological and Ripening Responses of Cabernet Sauvignon to Plant Growth Regulators Under Drought and Heat Stress

Adan Solis, Guadalupe Partida, Vincenzo Cianciola, Alessandro De Rosa, Marco Saldivar, Xavier Rideout, William Whalen and Luca Brillante*

*Department of Viticulture and Enology, California State University Fresno, 2360 E Barstow Ave, Fresno, CA, 93740, lucabrillante@csufresno.edu

High temperatures and water stress can significantly affect vine physiology and grape ripening, highlighting the need for effective strategies to optimize plant responses. Plant growth regulators (PGRs), including abscisic acid (ABA), ethylene, and salicylic acid, have been proposed to modulate stress responses and ripening processes in grapevines. However, their comparative effects in winegrapes remain underexplored. This study aimed to evaluate their influence on gas exchange, water stress tolerance, and grape composition in commercial settings. A field trial was conducted in a commercial Cabernet Sauvignon (Vitis vinifera L.) vineyard grafted onto 1103P rootstock in the Central Valley of California, a hot and arid climate, using a randomized complete block design with ABA, ethephon, and salicylic acid applied at veraison alongside an untreated control. Physiological responses were assessed throughout the ripening period, including leaf gas exchange, and midday stem water potential. At harvest, fruit composition—including total soluble solids (TSS), pH, and titratable acidity—was analyzed using high-performance liquid chromatography, while yield components were recorded. Salicylic acid-treated vines exhibited lower stress levels, indicated by fewer negative midday stem water potential values than the control. In contrast, ethephon-treated vines had more negative midday stem water potential values, suggesting increased water stress. In the early ripening phase, salicylic acid increased An and g_s, but these parameters declined in the later stages. ABA-treated vines exhibited higher TSS at harvest, while no significant effects on yield were observed across treatments. These findings suggest that salicylic acid can enhance stress tolerance and early-season carbon assimilation, while ABA can accelerate sugar accumulation without affecting yield. The study provides insights into the potential role of PGRs in modulating vine stress responses and ripening dynamics under field conditions. Further research is needed to refine application strategies and assess their long-term effect on vineyard performance.

Funding Support: Bronco Wine Co. Chair in Viticulture

Effects of Calcium Carbonate and Diatomaceous Earth on Vine Physiology and Grape Composition in a Hot, Arid Climate

Marco Saldivar, Guadalupe Partida, Vincenzo Cianciola, Alessandro De Rosa, Adan Solis, Xavier Rideout, William Whalen and Luca Brillante*

*Department of Viticulture and Enology, California State University Fresno, 2360 E Barstow Ave, Fresno, CA, 93740, lucabrillante@csufresno.edu

High temperatures and water stress can significantly affect vine physiology and grape quality, highlighting the need for effective mitigation strategies. Particle films such as calcium carbonate have been explored as potential tools to improve plant resilience under challenging environmental conditions. A field trial was conducted in a commercial Cabernet Sauvignon (Vitis vinifera L.) vineyard grafted onto 1103P rootstock in the Central Valley of California, a hot and arid climate, using a randomized complete block design with calcium carbonate and diatomaceous earth applied twice—at veraison and two weeks later—alongside an untreated control. Throughout the ripening period, physiological parameters such as net assimilation, stomatal conductance, and leaf temperature were monitored. The grape composition was measured routinely during ripening, including total soluble solids (TSS), pH, titratable acidity (TA), and anthocyanin profiles, while yield components were analyzed at harvest. Calcium carbonate slightly improved net assimilation in the second half of ripening, but had no effect on stomatal conductance. The control treatment exhibited slightly higher leaf temperatures during this period. Vines treated with diatomaceous earth exhibited consistently lower stem water potential throughout the experiment, beginning from an initially lower baseline, indicating a persistent trend rather than a treatment-induced response. Yield was not affected by either treatment. Regarding grape composition, calcium carbonate-treated vines produced fruit with higher pH and lower TA, which may be undesirable, while TSS remained similar in all treatments. These findings indicate that while calcium carbonate enhanced leaf carbon assimilation, it negatively affected berry acidity and pH balance. Diatomaceous earth-treated vines exhibited persistently lower stem water potential throughout the experiment, originating from an initially lower baseline, suggesting a consistent trend without clear physiological benefits. Further research is needed to determine whether these treatments could be optimized or if alternative approaches may be more effective in vineyard management under varying climatic conditions.

Funding Support: Bronco Wine Co. Chair in Viticulture

Ben-Min Chang* | Brad Estergaard | Steve Marsh

Cold Damage May be a Game of Probability

Ben-Min Chang,* Brad Estergaard and Steve Marsh

*Agriculture & Agri-Food Canada – Summerland Research & Development Centre, 4200 Highway 97 S, Summerland, British Columbia, V0H 1Z0, Canada, ben-min.chang@agr.gc.ca

Weakened polar vortex was the cause of 2022 and 2024 cold snaps in North America. The bulk of the freezing air from the arctic area spilled into the midlatitude region and caused extreme low air temperature with prolonged exposure. For example, the duration of the 2022 event with air temperature lower than -18°C lasted 42 hr at Summerland Research & Development Centre in the Okanagan Valley, British Columbia, Canada. Conventionally, the lowest temperature during the event is used to estimate damage. However, cases with greater-than-expected damage were observed in the affected regions. Previously, we observed the time to kill 50% of sampled buds increased at higher exposure temperature. The results suggested exposure temperature might determine the probability of bud death. To quantify the probability, we treated Merlot buds with 12 sets of constant temperature exposure at 1°C increments from -22°C to -11°C for 24 hr. Samples were taken when LTE50 were between -22.3°C and -22.8°C. Bud damage could be observed in the treatment experiencing average temperature at -12.3°C. The survival rate plummeted at temperatures below -15°C. We did not observe surviving buds after 24-hr exposure at -21.4°C. The survival rate of primary and secondary buds against exposure temperature can be described using the Hill equation. We then simulated the conventional cold hardiness testing process with temperature ramping from -6°C to -25°C at a rate of -3°C/hr. The bud survival probability in every 15-min exposure step was calculated. The simulated LTE50 was at -22.8°C. With the probability approach, we may develop a bud damage estimation tool. However, long-exposure experiments on buds during acclimation or de-acclimation phases are required.

Funding Support: Agriculture & Agri-Food Canada.

	Rapid Detection and Risk Assessment of Smoke-Derived Volatile Phenols: A Chemometric Approach using Spectrofluorometry Brandt Bastow, University of California, Davis Flash Talk: June 18, 2025, 4:30:00 pm
	Non-contact Post-fermentation Wine Processing to Remove Thiol-Related Smoke Compounds Lik Rong Lim, Oregon State University, Corvallis Flash Talk: June 18, 2025, 5:12:15 pm
	Wildfire Smoke-Taint Amelioration in Red Wines using Y Zeolite Connor Patton, University of California, Davis
	Barrier Spray Analyses for Mitigation of Smoke-Related Volatile Phenols in Cabernet Sauvignon Grapes Gauthier Lagarde, University of California, Davis
	Impacts of Methyl Jasmonate and Benzothiadiazole on Glycosylated Phenols in Grapes Exposed to Smoke Marker Compounds Chen Liang, University of California, Davis
	Validation of Protocols for Acid Hydrolysis of Smoke Related Glycosides Julie Hilland, Washington State University, Tri-Cities Flash Talk: June 18, 2025, 4:49:30 pm
	Examining the Role of Frost Damage on Leaf Composition to Unravel the Mystery of the “Frost” Taint Wine Phenomenon Mitchell Davey, Washington State University, Tri-Cities Flash Talk: June 18, 2025, 4:46:15 pm
	Investigation of Grape Skin Thickness and Grape Skin Lipid Content for Differences in Smoke Taint Composition Chanda Miller, Oregon State University, Corvallis Flash Talk: June 18, 2025, 5:15:30 pm
	Innovative & Sustainable Wine Fining: The Science Behind Plant Proteins Lorenza Allen, Enartis, California
	Evaluating the Impact of Cool and Warm Climate on Grenache blanc and Viognier Wine Quality in California’s Central Coast Coleman Imrisek, California Polytechnic State University, San Luis Obispo Flash Talk: June 18, 2025, 5:02:30 pm
	Evaluating the Impact of Cool and Warm Climate on Grenache and Syrah Wine Quality in California’s Central Coast Coleman Imrisek, California Polytechnic State University, San Luis Obispo
	Natural Biopolymer-Based Coatings to Improve Water-Use Efficiency and Heat Tolerance in Cabernet-Sauvignon Xavier Rideout, California State University, Fresno Flash Talk: June 18, 2025, 4:39:45 pm
	Environmental Drivers of White Winegrape Quality: A Survey of Chardonnay Ripening in Northern California Kaitlin Libbey, University of California, Davis
	Phenotypic Characterization and Cold Hardiness Assessment in Vitis Riparia and Vitis Amurensis Mapping Populations Hava Delavar, North Dakota State University, Fargo
	Soil Moisture and Soil Temperature Interact to Alter Grapevine Water Relations and Aquaporin Gene Expression Geraldine Diverres, Washington State University, Prosser
	How Grow-Tube Type Influences the Vine Microclimate in Winter Madison Shaw, Washington State University, Prosser Flash Talk: June 18, 2025, 4:49:30 pm
	Assessing Carbon Saturation Potential of Regeneratively Managed Vineyard Soils Gwendolyn Richards, California Polytechnic State University, San Luis Obispo Flash Talk: June 18, 2025, 4:56:00 pm
	Arbuscular Mycorrhizal Fungal Abundance and Diversity Across Vineyards in the Western United States Amanda Rodriguez, University of California, Davis Flash Talk: June 18, 2025, 4:59:15 pm
	Variability in the Vineyard: A Multi-method Approach in Determining Grapevine Evapotranspiration for Canadian Vineyards Jessica Williamson, University of Waterloo, Canada
	Linking Soil Carbon Stability and Microbial Diversity at Different Soil Depths in Northern California Vineyards Connie Wong, University of California, Davis
	Untargeted Metabolomic Analysis of Heat Stress Response in Cabernet Sauvignon Grapevines Samarth Rao, The University of Texas at Austin Flash Talk: June 18, 2025, 5:09:00 pm
	Chemical and Sensory Effects of Turbidity, Hyperoxygenation and Redox Potential on Grenache Blanc Wines from California Mia Pargellis, California Polytechnic State University, San Luis Obispo Flash Talk: June 18, 2025, 4:33:15 pm
	Assessing the impact of skin contact, redox potential and hyperoxygenation in Albariño wines from California Mia Pargellis, California Polytechnic State University, San Luis Obispo
	Kaolin an Zeolite Reduce Drought Damages to Gewürztraminer and Influence Berry Composition, must Quality and Wine Aroma Stefano Zanoni, University of Trento, Italy Flash Talk: June 18, 2025, 5:12:15 pm
	Evaluating Methods to Measure Free and Total Sulfur Dioxide in Wine Renee Threlfall, University of Arkansas, Fayetteville
	Detection and Identification of Glutathionyl-Flavan-3-ol Adducts in Red Wine Andrew L Waterhouse, University of California, Davis
	Te Whenua Tupu Living Lab: New Facility for Soil and Ecosystem Research for Sustainable Horticulture Cynthia Lund, The New Zealand Institute of Plant and Food Research, New Zealand
	Assessing the Economic Sustainability of Regenerative Viticulture in Sonoma County Axel Herrera, University of California, Davis
	High-Resolution Approaches to Vineyard Nutrient Optimization Nataliya Shcherbatyuk, Washington State University, Prosser
	Exploring Challenges and Needs of the US Grape and Wine Industry: A Western Region Focus Aude A. Watrelot, Iowa State University, Ames
	Effects of Varying Concentrations of Sulfur Dioxide at Bottling Aude A. Watrelot, Iowa State University, Ames
	Selective Phenolic Extraction During Cold Soak of Bordeaux Varietals Musts using Bipolar Pulsed Electric Fields Mafalda Aguiar Macedo, EnergyPulse Systems, Portugal
	Effects of Micro-Oxygenation and Redox Potential Control by Air Sparging During Alcoholic Fermentation on Syrah Wines Jordan Wright, California Polytechnic State University, San Luis Obispo Flash Talk: June 18, 2025, 4:36:30 pm
	Chemical Effects of Oxidation Reduction Potential on Syrah, Grenache and Mourvèdre Wines and Their Blends Jordan Wright, California Polytechnic State University, San Luis Obispo
	Optimizing Strategies for Acid Management in Red Wines from the Central Coast of California Charlotte Drop, California Polytechnic State University, San Luis Obispo Flash Talk: June 18, 2025, 4:43:00 pm
	Haskap Variety and Winemaking Process Evaluations Aditya Anand, North Dakota State University, Fargo
	Ripening Kinetics and Grape Chemistry in Petit Manseng, a Non-traditional Variety of Vitis vinifera Joy Ting, Virginia Winemakers Research Exchange, Charlottesville
	Proximal Multispectral Imaging and Artificial Neural Networks for Assessing Grape Ripeness and Quality in Vineyards Carlos Perez Perez, Tec de Monterrey, Mexico Flash Talk: June 18, 2025, 5:05:45 pm
	Profiling Texas-Grown and -Produced Wines Using Untargeted LC-MS-Based Metabolomics Delaney Dyer, The University of Texas at Austin Flash Talk: June 18, 2025, 5:18:45 pm
	Deficit Irrigation Strategies for Sustainable Grapevine Production in the San Joaquin Valley: Three Years of Insights Vincenzo Cianciola, California State University, Fresno Flash Talk: June 18, 2025, 4:43:00 pm
	Creating a Practical Approach to Predict Grapevine Water Status by Precision Viticulture Technologies Runze Yu, California State University, Fresno
	Improving Vineyard Resilience against Climate Change by Trellis Selection and Applied Irrigation Amounts Runze Yu, California State University, Fresno
	Calibrating a New Short-Wave Near-Infrared Spectroscopy Sensor for Measuring Table Grape Maturity Joy Hollingsworth, University of California Cooperative Extension, Tulare County
	Advancing Tannin Quantification in Wines: A Rapid, Reliable Approach with Machine Learning & BioSystems SPICA® analyzer Marilyn Garcia Tenesaca, BioSystems, Spain
	A New Method for Tannin Fingerprinting and Quantification via LC-MS/MS-Electrospray Ionization In-Source Fragmentation Yanxin Lin, The Pennsylvania State University, State College Flash Talk: June 18, 2025, 4:52:45 pm
	Enhancing Precipitable Tannin Quantification: A Validated, Ready-to-Use Alternative to Traditional Methods Jose Morales Ariza, BioSystems, Spain
	Characterizing Oregon Vineyard and Winery Brettanomyces Strains for Spoilage Potential C. Michael Sonza, Oregon State University, Corvallis Flash Talk: June 18, 2025, 4:39:45 pm
	Biofilm of Oenococcus oeni on Yeast Derivatives: Trigger Malolactic Fermentation, Modulate the Characteristics of Wine Anne Flesch, Fermentis, Wisconsin
	Enhancing Wine Acidity Through Lactic and Succinic Acid-Producing Yeast Strains Mirjam Fischer, University of California, Davis
	Identification of Novel Californian Saccharomyces cerevisiae Strains with Enological Potential Sydney Rogers, University of California, Davis Flash Talk: June 18, 2025, 4:56:00 pm
	Strain Selection and Timing of Malolactic Fermentation: Shaping the Chemistry of Pinot noir Wine Nicholas Mannino, Oregon State University, Corvallis Flash Talk: June 18, 2025, 4:59:15 pm
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	Conversion of Diglucoside Anthocyanins to Polymeric Pigments and their Influence on Wine Masashi HISAMOTO, University of Yamanashi, Japan
	Development of the New Method to Detect the Fungicide Resistance in Grape Downy Mildew using Aseptically Cultured Plants Kanako Sasaki, Kirin Holdings Company, Japan
	The Influence of Packaging Material on the Properties of Carbonated Blueberry Wine Under Accelerated Storage Conditions Nick Wendrick, University of Florida, Gainesville Flash Talk: June 18, 2025, 5:09:00 pm
	Screening for Fungicide Resistance in Botrytis cinerea from California Central Coast Vineyards Abraham Ahumada, California Polytechnic State University, San Luis Obispo
	Impact of Grapevine Red Blotch Virus (GRBV) Infection on Grape Cell Wall Ripening Enzymes Over Two Growing Seasons Arpa Boghozian, University of California, Davis
	Enhancing Grapevine Red Blotch Virus Detection: Multi-Vineyard Model Improvement and Deep Learning Integration Eve Laroche-Pinel, California State University, Fresno
	The Role of the Stomatogastric Nervous System in Controlling Feeding in Hemipteran Pests of Grapevines Paul Cooper, The Australian National University, Australia
	Survey and Characterization of Grape Black Rot in Oklahoma Tanner Dollar, Oklahoma State University, Stillwater Flash Talk: June 18, 2025, 4:46:15 pm
	Integrating UV-C and Canopy Management for Grape Powdery Mildew Control Jesse Stevens, Washington State University, Prosser Flash Talk: June 18, 2025, 4:52:45 pm
	Global Genetic Diversity and Population Structure of Grapevine Powdery Mildew Benny Ordonez, United States Department of Agriculture – Agricultural Research Service, California
	Integrative Multi-Omics Analysis of GRBV Effects on Grapevine: Unraveling Temporal, Genetic, and Metabolic Dynamics Prem Singh, University of California, Davis
	Effects of Air and Nitrogen Gas Mixing During Alcoholic Fermentation on the ORP, and Chemical Outcomes of Syrah Wines Dallas Parnigoni, California Polytechnic State University, San Luis Obispo
	Hyperspectral Phenolics: Exploring the Covariation between Leaf and Berry Reflectance and Berry Chemistry Alexandra Basquette, University of California, Davis
	Wine Technical Tasting Reveals No Yield Specific Sensory Relationship in Pinot noir Crop Load Trial Ainsley McCollum, Oregon State University, Corvallis Flash Talk: June 18, 2025, 5:05:45 pm
	Evaluating the Sensory Impacts of Fermentation Techniques on Tropical Fruit Aroma in Chardonnay Wines Mara Anton, Oregon State University, Corvallis
	Impact of Training System and Pruning Severity on Teroldego Grapevines in the San Joaquin Valley, California Marnelle Salie, Gallo, California Flash Talk: June 18, 2025, 5:02:30 pm
	Evaluation of Seven Rootstocks under Drought and Saline Condition for Wine Varieties in the Southern San Joaquin Valley Shijian Zhuang, University of California Cooperative Extension, Fresno County Flash Talk: June 18, 2025, 5:15:30 pm
	Understanding Spatial Variability of Vine Yield Components in Sonoma County Cabernet Sauvignon Vineyards Riley Hibbard, GALLO, California
	Strategies to Mitigate Heat Stress and Delay Berry Ripening in Grape Production Amid Climate Change Guadalupe Partida, California State University, Fresno Flash Talk: June 18, 2025, 4:30:00 pm
	Physiological and Ripening Responses of Cabernet Sauvignon to Plant Growth Regulators Under Drought and Heat Stress Adan Solis, California State University, Fresno Flash Talk: June 18, 2025, 4:33:15 pm
	Effects of Calcium Carbonate and Diatomaceous Earth on Vine Physiology and Grape Composition under a Hot, Arid Climate Marco Saldivar, California State University, Fresno Flash Talk: June 18, 2025, 4:36:30 pm
	Cold Damage Might be a Game of Probability Ben-Min Chang, Agriculture & Agri-Food Canada, Canada

2025 poster Session

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Poster Sessions 2025

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2025 poster Session

research Reports on Display

Poster Sessions 2025

Student Flash Talks

Chair:

Rapid Detection and Risk Assessment of Smoke-Derived Volatile Phenols: A Chemometric Approach using Spectrofluorometry

Non-Contact Postfermentation Wine Processing to Remove Thiol-Related Smoke Compounds

Wildfire Smoke-Taint Amelioration in Red Wines using Y Zeolite

Barrier Spray Analyses for Mitigation of Smoke-Related Volatile Phenols in Cabernet Sauvignon Grapes

Empacts of Methyl Jasmonate and Benzothiadiazole on Glycosylated Phenols in Grapes Exposed to Smoke Marker Compounds

Validation of Protocols for Acid Hydrolysis of Smoke-Related Glycosides

Examining the Role of Frost Damage on Leaf Composition to Unravel the Mystery of the “Frost Taint” Wine Phenomenon

Investigation of Grape Skin Thickness and Grape Skin Lipid Content for Differences in Smoke Taint Composition

Innovative and Sustainable Wine Fining: The Science Behind Plant Proteins

Evaluating the Impact of Cool and Warm Climate on Grenache blanc and Viognier Wine Quality in California’s Central Coast

Evaluating the Impact of Cool and Warm Climate on Grenache and Syrah Wine Quality in California’s Central Coast

Natural Biopolymer-Based Coatings to Improve Water-Use Efficiency and Heat Tolerance in Cabernet Sauvignon

Environmental Drivers of White Winegrape Quality: A Survey of Chardonnay Ripening in Northern California

Phenotypic Characterization and Cold Hardiness Assessment in Vitis riparia and Vitis amurensis Mapping Populations

Soil Moisture and Soil Temperature Interact to Alter Grapevine Water Relations and Aquaporin Gene Expression

How Grow-Tube Type Influences the Vine Microclimate in Winter

Assessing Carbon Saturation Potential of Regeneratively Managed Vineyard Soils

Arbuscular Mycorrhizal Fungal Abundance and Diversity Across Vineyards in the Western United States

Variability in the Vineyard: A Multi-Method Approach in Determining Grapevine Evapotranspiration for Canadian Vineyards

Linking Soil Carbon Stability and Microbial Diversity at Different Soil Depths in Northern California Vineyards

Untargeted Metabolomic Analysis of Heat Stress Response in Cabernet Sauvignon Grapevines

Chemical and Sensory Effects of Turbidity, Hyperoxygenation, and Redox Potential on Grenache blanc Wines from California

Assessing the Impact of SkinContact, Redox Potential, and Hyperoxygenation in Albariño Wines from California

Kaolin and Zeolite Reduce Drought Damage to Gewürztraminer and Influence Berry Composition, Must Quality, and Wine Aroma

Evaluating Methods to Measure Free and Total Sulfur Dioxide in Wine

Detection and Identification of Glutathionyl-Flavan-3-ol Adducts in Red Wine

Te Whenua Tupu Living Lab: A New Facility for Soil and Ecosystem Research for Sustainable Horticulture

Assessing the Economic Sustainability of Regenerative Viticulture in Sonoma County

High-Resolution Approaches to Vineyard Nutrient Optimization

Exploring Challenges and Needs of the United States Grape and Wine Industry: A Western Region Focus

Effects of Varying Concentrations of Sulfur Dioxide at Bottling

Selective Phenolic Extraction During Cold Soak of Bordeaux Varietal Musts Using Bipolar Pulsed Electric Fields

Effects of Microoxygenation and Redox Potential Control by Air Sparging During Alcoholic Fermentation of Syrah Wines

Chemical Effects of Oxidation Reduction Potential on Syrah, Grenache, and Mourvèdre Wines and Their Blends

Optimizing Strategies for Acid Management in Red Wines from the Central Coast of California

Haskap Variety and Winemaking Process Evaluations

Ripening Kinetics and Grape Chemistry in Petit Manseng, a Non-Traditional Variety of Vitis vinifera

Proximal Multispectral Imaging and Artificial Neural Networks for Assessing Grape Ripeness and Quality in Vineyards

Profiling Texas-Grown and -Produced Wines Using Untargeted Liquid Chromatography-Mass Spectrometry-Based Metabolomics

Deficit Irrigation Strategies for Sustainable Grapevine Production in the San Joaquin Valley: Three Years of Insights

Creating a Practical Approach to Predict Grapevine Water Status by Precision Viticulture Technologies

Improving Vineyard Resilience Against Climate Change by Trellis Selection and Applied Irrigation Amounts

Calibrating a New Short-Wave Near-Infrared Spectroscopy Sensor for Measuring Table Grape Maturity

Advancing Tannin Quantification in Wines: A Rapid, Reliable Approach with Machine Learning and a BioSystems SPICA Analyzer

A New Method for Tannin Fingerprinting and Quantification via LC-MS/MS-Electrospray Ionization In-Source Fragmentation

Enhancing Precipitable Tannin Quantification: A Validated, Ready-to-Use Alternative to Traditional Methods

Characterizing Oregon Vineyard and Winery Brettanomyces Strains for Spoilage Potential

Biofilm of Oenococcus oeni on Yeast Derivatives: Trigger Malolactic Fermentation, Modulate the Characteristics of Wine

Enhancing Wine Acidity Through Lactic and Succinic Acid-Producing Yeast Strains

Identification of Novel Californian Saccharomyces cerevisiae Strains with Enological Potential

Strain Selection and Fermentation Timing: Shaping the Chemistry of Pinot noir Wines

Inhibition of Pellicle Formation by a Solvent-Extracted Fraction from Non-Pellicle Wine

Conversion of Diglucoside Anthocyanins to Polymeric Pigments and Their Influence on Wine

A New Method to Detect Fungicide Resistance in Grape Downy Mildew Using Aseptically Cultured Plants

Influence of Packaging Material on the Properties of Carbonated Blueberry Wine Under Accelerated Storage Conditions

Screening for Fungicide Resistance in Botrytis cinerea from California Central Coast Vineyards

Impact of Grapevine Red Blotch Virus Infection on Grape Cell Wall Ripening Enzymes Over Two Growing Seasons

Enhancing Grapevine Red Blotch Virus Detection: Multi-Vineyard Model Improvement and Deep Learning Integration

Role of the Stomatogastric Nervous System in Controlling Feeding in Hemipteran Pests of Grapevines

Survey and Characterization of Grape Black Rot in Oklahoma

Integrating UV-C and Canopy Management for Grape Powdery Mildew Control

Global Genetic Diversity and Population Structure of Grapevine Powdery Mildew

Integrative Multi-Omics Analysis of GRBV Effects on Grapevine: Unraveling Temporal, Genetic, and Metabolic Dynamics

Effects of Air and Nitrogen Gas Mixing During Alcoholic Fermentation on the Oxidation-Reduction Potential and Chemical Outcomes of Syrah Wines

Hyperspectral Phenolics: Exploring the Covariation between Leaf and Berry Reflectance and Berry Chemistry

Wine Technical Tasting Reveals No Yield-Specific Sensory Relationship in Pinot noir Crop Load Trial

Evaluating the Sensory Impacts of Fermentation Techniques on Tropical Fruit Aroma in Chardonnay Wines

Effect of Training System and Pruning Severity on Teroldego Grapevines in the San Joaquin Valley, California

Evaluation of Seven Rootstocks Under Drought and Saline Condition for Wine Varieties in the Southern San Joaquin Valley

Understanding Spatial Variability of Vine Yield Components in Sonoma County Cabernet Sauvignon Vineyards

Strategies to Mitigate Heat Stress and Delay Berry Ripening in Grape Production Amid Climate Change

Physiological and Ripening Responses of Cabernet Sauvignon to Plant Growth Regulators Under Drought and Heat Stress

Effects of Calcium Carbonate and Diatomaceous Earth on Vine Physiology and Grape Composition in a Hot, Arid Climate

Cold Damage May be a Game of Probability

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Assessing the Impact of Skin
Contact, Redox Potential, and Hyperoxygenation in Albariño
Wines from California

Detection and Identification of Glutathionyl-Flavan-3-ol Adducts
in Red Wine

Te Whenua Tupu Living Lab:
A New Facility for Soil and Ecosystem Research for Sustainable Horticulture

Chemical Effects of Oxidation Reduction Potential on Syrah, Grenache, and Mourvèdre Wines
and Their Blends

Proximal Multispectral Imaging
and Artificial Neural Networks for Assessing Grape Ripeness and Quality
in Vineyards

A New Method for Tannin Fingerprinting and Quantification
via LC-MS/MS-Electrospray Ionization
In-Source Fragmentation

Enhancing Wine Acidity Through
Lactic and Succinic Acid-Producing
Yeast Strains

Identification of Novel Californian Saccharomyces cerevisiae Strains
with Enological Potential

Inhibition of Pellicle Formation by
a Solvent-Extracted Fraction from
Non-Pellicle Wine

Influence of Packaging Material
on the Properties of Carbonated
Blueberry Wine Under Accelerated
Storage Conditions

Screening for Fungicide Resistance
in Botrytis cinerea from California Central Coast Vineyards

Enhancing Grapevine Red Blotch
Virus Detection: Multi-Vineyard
Model Improvement and Deep
Learning Integration

Survey and Characterization
of Grape Black Rot in Oklahoma

Integrating UV-C and Canopy Management for Grape Powdery
Mildew Control

Global Genetic Diversity
and Population Structure of
Grapevine Powdery Mildew

Wine Technical Tasting Reveals No Yield-Specific Sensory Relationship
in Pinot noir Crop Load Trial

Strategies to Mitigate Heat Stress
and Delay Berry Ripening in Grape Production Amid Climate Change