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2026 Student Flash Talks Enology
June 17, 2026 – 5:00 pm – 5:30 pm
Enology
Select presentation title to view abstract.
Some student authors have been assigned oral, 3-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 17, 5:00 pm – 5:30 pm, at the Boise Centre, Boise, Idaho
Moderator:
To be announced
Speakers:
Charlotte Drop | Sean Kuster | Biljana Petrova | Robert Coleman | Miguel Pedroza | Federico Casassa*
Acid Management in Warm-Climate Tempranillo Wines
Charlotte Drop, Sean Kuster, Biljana Petrova, Robert Coleman, Miguel Pedroza, and Federico Casassa*
*Wine and Viticulture Department, Cal Poly San Luis Obispo, Justin and J. Lohr Center for Wine and Viticulture, Building 156, Office 116, 1 Grand Avenue, San Luis Obispo, CA, 93407, lcasassa@calpoly.edu
Tempranillo wines from the Central Coast of California were produced using three acid management strategies in addition to a control: addition of 0.9 g/L fumaric acid (FA) before alcoholic fermentation to inhibit malolactic fermentation (MLF), fermentation with lactic acid-producing Lachancea thermotolerans (Omega strain), and ion exchange (IE) treatment of juice followed by blending at a 30% proportion before alcoholic fermentation. All treatments were co-inoculated with malolactic bacteria on Day 2 of alcoholic fermentation, with the exception of FA. FA wines showed higher tannins (12.6%) and total phenolics (12.1%) than the control. FA was the least effective at reducing pH, decreasing it by 0.07 units and increasing titratable acidity (TA) to 6.98 g/L compared to 6.04 g/L in the control. Inhibition of MLF with FA resulted in wines with the least lactic acid (0.21 g/L versus 0.55 g/L in the control), most malic acid (2.16 g/L versus 1.21 g/L), and least acetic acid (0.03 g/L versus 0.18 g/L). Lachancea produced the most lactic acid (3.76 g/L) and was most effective at increasing TA (9.22 g/L). Lachancea wines exhibited the highest odor activity value for isoamyl acetate and FA wines for ethyl butyrate (271 and 37.6% higher than the control, respectively). The 30% IE juice wines had 18.5% less anthocyanins, 27.8% less total polymeric pigments, 8.6% less tannins, and 13.6% less total phenolics than the control. These wines also had the lowest pH, reduced by 0.42 units, the lowest potassium (14.9% less than the control) and the most tartaric acid (2.93 g/L versus 2.64 g/L). Sensory analysis is underway.
Funding Support: Richard Lauchland (Duas Terras Vineyard) is thanked for their donation of fruit.
Brannigan du Preez | Nicolas Delchier | Aude A. Watrelot*
Alternatives to Sulfur Dioxide: How Efficient Are They?
Brannigan du Preez, Nicolas Delchier, and Aude A. Watrelot*
*Iowa State University, 536 Farm House Lane, Ames, IA, 50011, watrelot@iastate.edu
In response to consumer demand for reduced chemical inputs, winemakers are exploring strategies to lower sulfite additions while maintaining wine quality. Producing high-quality wines with reduced SO₂ remains challenging because of the increased risk of microbial spoilage and oxidation. Consequently, alternatives such as chitosan and enological tannins are gaining interest for their potential protective effects. Previous work showed no significant differences in phenolic concentration, hue, or color intensity in La Crescent wines when low free SO₂ levels (30 mg/L) were added at bottling, suggesting that minimal SO₂ may be sufficient to preserve color and quality during aging. The present study evaluated the effect of chitosan and enological tannins applied during winemaking on the quality of Frontenac and La Crescent wines, compared with wines produced using conventional SO₂ additions. Chemical parameters including free and total SO₂, color, and phenolic content, were assessed. In addition, levels of dissolved oxygen in wines at 7 and 11 cm from the neck were followed for 5 mo. La Crescent wines produced without SO₂ exhibited seven times more dissolved oxygen at bottling, lower phenolic concentrations, and reduced color intensity compared with wines made with SO₂. In contrast, Frontenac wines showed similar color intensity across treatments despite higher monomeric anthocyanin concentrations in wines produced with SO₂. The concentration of acetaldehyde, along with bacterial and yeast populations, will be evaluated after 5 mo of aging to further assess wine stability. These findings suggest that the effectiveness of SO₂ alternatives may be cultivar-dependent, highlighting the need for tailored sulfite-reduction strategies to maintain wine quality and stability.
Funding Support: USDA-AMS Iowa Specialty Crop Block Grant Program (SCBGP) through USDA grant 25SCBPIA1299
Amanda Fleming | Renee Threlfall*
Effect of Lachancea thermotolerans Yeast Strains on Acids and Sugars during Chambourcin Wine Fermentation
Amanda Fleming and Renee Threlfall*
*University of Arkansas, 2650 N. Young Ave, Fayetteville, AR, 72704, rthrelf@uark.edu
There is increased interest in using non-Saccharomyces yeasts such as Lachancea thermotolerans (LT) to enhance complexity and resolve challenges with low acidity in wines. Thus, the effect of different LT strains on acids and sugars of musts/wines during fermentation at 21°C for 15 days and at bottling were evaluated. In 2024, 263 kg of Arkansas-grown Chambourcin (Vitis hybrid) grapes were hand-harvested, randomized into batches, crushed, and destemmed. Seven inoculation treatments in duplicate were conducted using Saccharomyces cerevisiae(SC) and three LT strains including a commercial strain (Laktia™) and two experimental strains (LT1 and LT2), receiving sequential SC inoculations after 24 or 48 hr. All treatments were co-inoculated with malolactic bacteria 24 hr after inoculation with SC. At harvest, grapes had 20.29% total sugars, pH 3.52, 0.88% titratable acidity (TA), 0.77 to 0.85% malic acid, 0.02 lactic acid, and 1.06% total organic acids. All treatments completed alcoholic fermentation by day 10, when SC wines had the highest pH (3.71) compared to all other treatments. At day 10, SC wines had 0.71% TA, but wines fermented with LT had 0.84 to 1.06%. From days 7 to 14, LT1-SC-48 hr wines had higher lactic acid (0.38 to 0.40%) compared to SC and Laktia wines (0.16 to 0.26%), regardless of timing of sequential inoculation. At bottling, all wines produced with LT had lower pH (3.48 to 3.59) compared to SC wines (3.69), except for Laktia-SC-24 hr and LT2-SC-24 hr wines. TA was highest in the LT1-SC-48 hr wines (0.93%). LT1-SC-48 hr wines had the highest lactic acid (0.40%) compared to all other wines (0.22 to 0.34%). LTstrains in mixed inoculation with SC produced Chambourcin wines with lower pH and higher TA and lactic acid, offering a fermentation approach to enhance acidity, stabilize microbial balance, and address winemaking challenges in warm-climate regions.
Funding Support: Lallemand Oenology
Sydney Goodman* | Annegret Cantu | Ha Nguyen
Dose-Response Effects of Ethanol on Oral Sensations: Baseline Data for Non-Alcoholic Wine Formulation
Sydney Goodman,* Annegret Cantu, and Ha Nguyen
*University of California, Davis, 595 Hilgard Ln, Davis, CA, 95616, sdgoodman@ucdavis.edu
Traditional wines rely heavily on ethanol-induced activation of the Transient Receptor Potential Vanilloid 1 (TRPV1) receptor to produce heating and other mouthfeel sensations that are absent in non-alcoholic (NA) wines. Understanding how a wine matrix influences TRPV1-activated alcohol perceptions may help identify compounds that can replace ethanol’s sensory effects in NA wine. This study aims to generate dose-response curves for ethanol and potential TRPV1-activated ingredients (e.g., capsaicin, gingerols, piperine) in water and de-alcoholized wine for heating/tingling, sourness, sweetness, bitterness, and astringency. In a pilot sensory panel, 13 untrained panelists evaluated nine water-based and nine NA wine-based samples, with ethanol concentrations of 0, 4.2, 5.25, 6.56, 8.19, 10.24, 12.8, 16, and 20%. Samples were served in randomized order among participants, using a swish-and-spit protocol. Attribute intensities were recorded in Compusense using the Generalized Labeled Magnitude Scale (gLMS). There were large individual differences in perceived sensory intensities across all samples. A two-way analysis of variance revealed significant interactions between ethanol concentration and solution type. Participants perceived a sensory difference at concentrations as low as 5.25% in water, but not until 8.19% in NA wine. Besides sweetness, other attributes changed with increasing concentration. The average intensity of 5.25% ethanol in water was moderate for heating/tingling and astringency, and weak for sourness. In NA wine, increasing ethanol concentration increased astringency and decreased sourness and sweetness, demonstrating ethanol’s role in altering multiple sensory attributes. At the highest concentration (20%), the wine matrix suppressed heating/tingling by ~42% compared to water. Data collection on capsaicin and gingerols is ongoing using the same protocol. We will then expand data collection to 30 participants. Knowledge of the sensory perception of ethanol and potential substitutions, and their effects on wine sensory attributes, will help guide the formulation of no- or low-alcoholic wines that are acceptable to consumers.
Funding Support: Ha Nguyen: Nguyen Research Funds at UC Davis Viticulture & Enology
Andrew J. Makowski* | Randall Vos | Joey Talbert | Erin Norton
A Targeted LC-MS/MS Method for Quantifying Amino Acids in Cold-Hardy Grape Juice and Wine
Andrew J. Makowski,* Randall Vos, Joey Talbert, and Erin Norton
*Iowa State University, 536 Farm House Lane, 2575 Food Science Building, Ames, IA, 50011, drewmak@iastate.edu
Cold-hardy grape cultivars differ from Vitis vinifera by producing a chemically complex fermentation matrix with elevated protein content, diverse free amino acid pools, and compositional shifts during fermentation. Traditional nitrogen metrics such as yeast assimilable nitrogen (YAN) lack the resolution to capture amino acid-specific dynamics that directly influence yeast metabolism, fermentation kinetics, and aroma formation. To address this analytical limitation, a targeted liquid chromatography tandem mass spectrometry (LC-MS/MS) method was developed to enable high-resolution, quantitative profiling of individual amino acids in grape juice and fermented wine. The method was designed to operate across chemically diverse matrices, accounting for high organic-acid content, ethanol, and matrix effects typical of fermentations of high-protein, cold-hardy cultivars. Direct sample preparation using only centrifugation was optimized for rapid throughput while preserving amino acid integrity. Chromatographic separation was performed by reversed-phase liquid chromatography, followed by tandem mass spectrometric detection with multiple reaction monitoring of amino acid-specific transitions. Stable retention times, compound-specific ion ratios, and deuterated internal standards were used to ensure analytical confidence, reproducibility, and accuracy for targeted analytes. Method performance was evaluated for linearity, sensitivity, repeatability, and matrix effects in both juice and wine. The resulting method enables simultaneous quantification of free amino acids across fermentation stages, providing a detailed nitrogen speciation profile that conventional assays cannot capture. When paired with complementary acid profiling by high-performance liquid chromatography and volatile analysis by headspace solid-phase microextraction gas chromatography-mass spectrometry, this LC-MS/MS method enables interrogation of nitrogen utilization and metabolic outcomes with molecular specificity. This analytical framework lays the groundwork for mechanistic investigation of nitrogen behavior in fermentation systems and supports data-driven modeling of yeast nutrient utilization. More broadly, the method provides a transferable tool for fermentation research in which amino acid composition rather than bulk nitrogen concentration governs biological and sensory outcomes.
Funding Support: USDA – Specialty crop block grant program
Amelia Pargellis | Sean Kuster | Biljana Petrova | Robert Coleman | James Nelson | Miguel Pedroza | Federico Casassa*
Reductive Versus Oxidative Winemaking Effects on the Chemical Composition and Sensory Profile of Vermentino Wines
Amelia Pargellis, Sean Kuster, Biljana Petrova, Robert Coleman, James Nelson, Miguel Pedroza, and Federico Casassa*
*Wine and Viticulture Department, Cal Poly San Luis Obispo, JUSTIN and J. LOHR Center for Wine and Viticulture, Building 156, Office 116, 1 Grand Avenue, San Luis Obispo, CA, 93407, lcasassa@calpoly.edu
Vermentino grapes (pH 3.41, Brix 22.5, titratable acidity 5.5 g/L) were pressed and split into three treatments, namely Control, N2 (reductive) handling, and Air (oxidative) handling. Control juice received 50 ppm SO2 and CO2 blanketing, N2 was bubbled with nitrogen for 2 hr at 1000 mL/L/hr, and Air underwent hyperoxygenation for 2 hr at 1000 mL/L/hr. Control and N2 were inoculated with VL3 (Laffort). Meanwhile, Air was further split into two treatments: AirVL3, which was inoculated with VL3; and AirMon, which was inoculated with Lalvin M (Montrachet strain, Lallemand). Further, during fermentation N2 and AirMon received glutathione. Oxidation-reduction potentials (ORP; Ag/AgCl reference electrode) during juice processing stayed at 125 mV for Control and 50 mV for N2, demonstrating that an addition of SO2 was sufficient to maintain a low prefermentation ORP. The addition of ascorbic acid on N2 only made a marginal difference in ORP when SO2 was present. Air, which received no SO2, averaged 313 mV prior to hyperoxygenation and a peak of 420 mV and dissolved oxygen (DO) of 4.6 mg/L during hyperoxygenation. Passive hyperoxygenation led to an increase of almost 200 mV in ORP over the Control. Average phenolics were 141 mg/L for Control, 120 mg/L for N2, and 20 mg/L for AirVL3 and AirMon. Total ester odor activity values were highest for Control, and 15, 23, and 37% lower than Control for N2, AirVL3, and AirMon, respectively. Overall, the extremely reductive environment of the juice and fermentation stage for Control and N2 led to wines that were objectionable due to their H2S levels. Comparatively, hyperoxygenation in conjunction with yeast choices can achieve reductive (AirMon) versus oxidative (AirVL3) style wines.
Funding Support: Richard Lauchland (Duas Terras Vineyard) and Treasury Wine Estates (St. Helena, California) are thanked for their donation of fruit and logistical support, respectively.
Julissa Preciado | Federico Casassa* | Bilijana Petrova | Sean Kuster
Effect of Prefermentation Manipulations on the Balance of Terpenic Gewürztraminer
Julissa Preciado, Federico Casassa,* Bilijana Petrova, and Sean Kuster
*Wine and Viticulture Department, Cal Poly San Luis Obispo, JUSTIN and J. LOHR Center for Wine and Viticulture, Building 156, Office 116, San Luis Obispo, CA, 93407, lcasassa@calpoly.edu
Prefermentation treatments conducted on Gewürztraminer from Monterey County, CA were established to produce varying levels of acidity to evaluate volatile aroma development and sensory features related to wine balance. Gewürztraminer underwent a control treatment and a 22.7% waterback addition, chaptalization, and 30% ion exchange of its juice at pressing. Across all volatiles at pressing, the control and chaptalized treatments resulted in the highest concentrations of terpenes and esters. Specifically, chaptalization enhanced the following esters and higher alcohols associated with fruit and floral notes: isoamyl acetate, ethyl decanoate, and 2-phenylethyl, while the control treatment preserved floral terpene b-citronellol. Ion exchange and waterback treatments produced the lowest concentration of the same volatiles; however, the ion exchange treatment produced the highest amount of linalool while specifically lowering isoamyl acetate, ethyl decanoate, and geraniol. The waterback treatment tended to mute all aromas. Similar patterns to volatile production emerged in odor activity values (OAVs) across treatments. In addition to prefermentative treatments, a portion of juice was collected and either ion exchanged or frozen to conduct süssreserve, a postfermentative treatment used to introduce residual sugar. While chemical differences were apparent across acidity, alcohol, and aroma production, further treatments including süssreserve, de-alcoholization, and CO2 additions and sensory analysis are underway to evaluate the role of acidity, residual sugar, and ethanol content on perceived wine balance.
Funding Support: Scott Williams (Coastal Vineyard Care), Stephan L’Aseo (L’Aventure Winery, Paso Robles, CA), and Treasury Wine Estates (St. Helena, CA) are thanked for their donation of fruit and logistical support, respectively.
