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2025 Student Flash Talks Enology
June 18, 2025 – 4:30pm – 5:30pm
Enology
Some student authors have been assigned oral, 3.25-minute Flash Talks. These “flash” presentations will provide additional opportunities for interaction between conference attendees and student researchers.
Flash Talks will take place on Wednesday, June 18, 4:30 pm – 5:30 pm, at the Portola Hotel in Monterey, California.
Moderator:
Karen Block, University of California, Davis
Speakers:
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
Mia Pargellis | Federico Casassa* | Biljana Petrova | James Nelson | Sean Kuster | Bob Coleman | Jesus Villalobos
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
Jordan Wright | Sean Kuster | Biljana Petrova | James Nelson | Bob Coleman | Federico Casassa*
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
C. Michael Sonza | Emily Kaneshiro | Tess Snyder | Bjarne Bartlett | James Osborne | Christopher Curtin*
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
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
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
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
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
Sydney Rogers | Mirjam Fischer | Jackson Moore | Annegret Cantu | Larry Lerno | Hildegarde Heymann | Vivien Measday | Ben Montpetit*
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
Coleman Imrisek | Mercy Torres | Ozan Gencer | Sean Kuster | Federico Casassa | Miguel Pedroza*
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
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
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.
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
Delaney Dyer | Samarth Rao | Nicholas Bastia | Chloe O’Patry | Diana Zamora-Olivares* | Eric Anslyn
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
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
