2024 Enology Sessions

  • Enology – Sensory of Grapes and Wine Session

    June 19, 2024 – 8:15am – 9:55am

    Research Reports

    Location: Marriott Portland Downtown Waterfront

    Moderator: 

    P. Layton Ashmore, Washington State University, Tri-Cities

    Speakers:

    8:15 am – 8:35 amSurveying U.S Fresh-Market Grape Consumers to Determine Key Attributes and Willingness to Pay
    Renee Threlfall, University of Arkansas, Fayetteville
    8:35 am – 8:55 amComparison of Pre- and Postfermentation Alcohol Manipulation of Cabernet Sauvignon Wines
    Danielle Fox, Washington State University, Tri-Cities
    8:55 am – 9:15 amEffect of Cap Management Protocols on Phenolic Composition, Redox Potential, and Sensory Properties of Pinot noir Wines
    Dallas Parnigoni, California Polytechnic State University, San Luis Obispo
    9:15 am – 9:35 amAssessing the Effect of Grape Smoke Exposure on Different Red Wine Varietals using Instrumental and Sensory Analysis
    Lik Xian Lim, University of California, Davis
    9:35 am – 9:55 amThe Efficacy of Common Winemaking Practices on Reducing Wildfire-Smoke Flavor Perception in Cabernet Sauvignon Wines
    Elizabeth Tomasino, Oregon State University, Corvallis

    Renee Threlfall | Margaret Worthington | Melinda Knuth| Di Fang | Wie Yang | Amanda Fleming | Penny Perkins-Veazie | Mark Hoffmann

    Surveying U.S Fresh-Market Grape Consumers to Determine Key Attributes and Willingness to Pay

    Renee Threlfall,* Margaret Worthington, Melinda Knuth, Di Fang, Wie Yang, Amanda Fleming, Penny Perkins-Veazie, and Mark Hoffmann
    *University of Arkansas, 2650 N. Young Ave, Fayetteville, AR, 72704 (rthrelf@uark.edu)

    Grapes (genus Vitis) have two subgenera, Vitis and Muscadinia. While Vitis (especially Vitis vinifera) is the backbone of the grape and wine industry, it can be challenging to grow in many U.S. states due to disease susceptibility. Current grape breeding efforts focus on introgressing disease resistance from Muscadinia to Vitis and quality traits from Vitis to Muscadinia, resulting in new wide-hybrid cultivars. In 2023, an online survey was distributed targeting U.S. consumers of fresh-market grapes to assess demographics, purchase habits/intent, and willingness-to-pay (WTP). Consumers were screened based on age (over 18-years-old), residing in the U.S., and purchase of grapes in last 12 months, with a quarter of respondents from each U.S. area (southeast, northeast, northwest, and southwest). For the discrete choice experiment, there were 24 WTP choice sets (bunch grape, muscadine grape, or neither) with five price levels per pound ($2, $3, $4, $5, and $6), flavor (strong or mild), texture (soft or firm/crisp), size (small, medium, or large), seed presence (none or present), and color (purple/black, pink/red, or light/green). Consumers (n = 950) were 51% female, averaged age 45, had income of $95,000, and were mostly white/Caucasian (86%). Consumers purchased fruit from grocery stores (89%), super discount stores (43%), direct from the farm (30%), online (20%), or at health food stores (15%). Consumers ranked fruit attributes from most to least important (freshness, flavor, price, seed presence, texture, color, size, nutritional content, production style, and shopping environment). Consumers were willing to pay more for muscadine grapes ($5.57), firm texture ($1.44), and no seeds present ($3.59), but less for pink/red color ($0.94) or purple/black color ($0.69), and consumers had no preference for fruit size. Results indicated a consumer demand for both bunch and muscadine grapes, preference for firm, green, seedless grapes, and tendency to purchase from traditional fruit purchasing channels.

    Funding Support: USDA NIFA Specialty Crop Initiative (SCRI) planning grant team for “Through the Grapevines: Building Research and Extension Potential between Subgenera Vitis and Muscadinia for the U.S. Grape Industry” (Award # 2022-51181-38326)

    Danielle Fox | James Harbertson

    Comparison of Pre- and Postfermentation Alcohol Manipulation of Cabernet Sauvignon Wines

    Danielle Fox and James Harbertson*
    *Washington State University, 2710 Crimson Way, Richland, WA, 99354-1671 (jfharbertson@wsu.edu)

    Cabernet Sauvignon grapes were harvested at three potential alcohols (11, 13.5, and 16% v/v, ABV) from a vineyard in Sunnyside, Washington in 2018 and 2019.  Alcohol was controlled for pre-fermentation by either dilution or chaptalization. At each harvest, the 13.5 and 16.0% ABV wines were dealcoholized to 11 and 13.5% ABV using a pilot-scale dealcoholization (DA). The initial experimental alcohol was treated as the control, the dealcoholized wine the treatment, and the wine sharing the same alcohol target and harvest date as the dealcoholized wine was designated as the negative control. Basic wine chemistry was determined and untargeted solid-phase microextraction gas chromatography-mass spectrometry was used to identify major aroma compounds present. Targeted analysis was performed on various classes of wine aromatics (alcohols, esters, aldehydes, terpenes, pyrazines) informed by the untargeted analysis. Descriptive analysis was performed on the 2019 wines by nine panelists (four males). Three taste, three mouthfeel, five ortho-, and seven retro-nasal aroma attributes were significant. DA had no significant affect on any basic wine chemistry other than the intended alcohol. For all aroma compound classes measured, the negative control and dealcoholized treatments were significantly lower in concentration than the higher ABV controls. Similarly, the retro- and ortho-nasal aroma attributes were rated lower intensity in the negative control and DA treatments than in the higher ABV controls. Generally, the experiment shows that dealcoholization is not absorbing or “scalping” aroma compounds. Instead, the reduction of aroma compounds is due to volatile compound partitioning effects that are directly influenced by ethanol concentration. These results show that wine aromas, and thus wine styles, may be manipulated postfermentation by dealcoholization.

    Funding Support: Washington Wine Commission

    Federico Casassa | Sean Kuster | Grace Putman | Gabriela Rivas | Dallas Parnigoni | Emily Stoffel | James Nelson | Bob Coleman

    Effect of Cap Management Protocols on Phenolic Composition, Redox Potential, and Sensory Properties of Pinot noir Wines

    Federico Casassa,* Sean Kuster, Grace Putman, Gabriela Rivas, Dallas Parnigoni, Emily Stoffel, James Nelson, and Bob Coleman
    *Wine and Viticulture Department, California Polytechnic State University San Luis Obispo (Cal Poly), 1 Grand Avenue, San Luis Obispo, CA, 93407 (lcasassa@calpoly.edu)

    Pinot noir wines from the Sta. Rita Hills AVA of California were produced with five contrasting cap management protocols: pump-overs, performed at two full-volumes/day (PO); punch-downs, performed twice/day for 3 min each (PD); no cap management (NoCMgmt); air mixing, at two additions/day (AM); and nitrogen mixing, at two additions/day (NM). Redox potential spikes up to 340 mV were observed during maceration in AM wines. NM wines consistently showed negative mV values with subtle -40 mV spikes during N mixing. Temperature was controlled during fermentation (24 to 28°C), trending 2°C lower in PO wines. Alcoholic fermentation was completed in all wines within 10 days, with a slower rate of total soluble solids depletion in NoCMgmt wines. PO wines had lower alcohol levels (12.76%) than PD wines (13.76%), and acetic acid doubled in AM wines. AM wines showed the lowest levels of acetaldehyde and NoCMgmt the highest. Anthocyanins and tannins were 50% lower, and total phenolics were 44% lower in AM wines. Total polymeric pigment formation was favored in PD wines at 40% higher and 42% higher relative to PO and AM wines, respectively. The tannin, anthocyanin, total phenolic, and chromatic profiles of PD and NM wines were statistically indistinguishable, but lower in NoCMgmt wines, and the lowest in AM wines. An accelerated aging experiment was established by placing the wines in air-tight glass ampoules, then incubating them for five weeks at 38°C. After accelerated aging, alcohol, pH, titratable acidity, acetic acid, tannin, and total phenolics levels were essentially unchanged and consistent with those measured at bottling. Whereas anthocyanins dropped by 70% and polymeric pigments increased by 106% across all wines, the trend described at bottling for these phenolics persisted. Sensory analysis is currently underway. Present results emphasize the well-documented subpar effects of excessive oxygen dissolution, even during alcoholic fermentation, on Pinot noir wines.

    Funding Support: Star Lane and Dierberg Vineyards, LLC (Santa Ynez, CA, USA), E. & J. Gallo Winery (Healdsburg, California, USA), and Treasury Wine Estates (St. Helena, California, USA).
     

    Lik Xian Lim | Cristina Medina-Plaza | Ignacio Arías-Perez | Yan Wen | Bishnu Neupane | Larry Lerno | Jean-Xavier Guinard | Anita Oberholster

    Assessing the Effect of Grape Smoke Exposure on Different Red Wine Varietals using Instrumental and Sensory Analysis

    Lik Xian Lim, Cristina Medina-Plaza, Ignacio Arías-Perez, Yan Wen, Bishnu Neupane, Larry Lerno, Jean-Xavier Guinard, and Anita Oberholster*
    *UC Davis, 595 Hillgard Lane, Department of Viticulture and Enology, Davis, CA, 95616 (aoberholster@ucdavis.edu)

    Fresh smoke from wildfires releases volatile phenols (VPs) due to the thermal degradation of wood lignin. VPs are absorbed into grape berries and rapidly glycosylated. Wines made from smoke-affected grapes are characterized as having smoky, medicinal aromas and a retro-nasal ashy aftertaste. Around 15 to 20% of general consumers are anosmic towards the ashy character of smoke. This study investigated the baseline levels of VPs in grapes across seven different red wine varietals spread across California and the sensory differences between the smoke-affected and non-smoke-affected wines using modified descriptive analysis (DA), gas chromatography-mass spectrometry, and liquid chromatography-triple quadrupole tandem mass spectrometry of the free and total VPs, and individual bound glycosides, respectively. The amount of smoke exposure was the largest contributor to smoke impact, but different wine matrices from different locations and varietals were also important in determining the level of perceived smoke impact. Low smoke-affected wines determined by free and total VP concentrations were not significantly different from the non-affected wines when rated by DA. The study also investigated the difference between the sensitivity of experts and non-experts towards smoke. From the same location, smoke-affected and non-smoke-affected wines made from Cabernet Sauvignon, Malbec, and Syrah grapes, respectively, were blended through serial dilutions to achieve wines with different levels of smoke impact. Wines were evaluated using a series of hedonic questions, just-about-right, and check-all-that-apply. The results indicate that experts could determine smoke impact at lower percentages of smoke-affected wine included in the wine blend than non-experts, who only distinguished smoke impact at higher percentages of smoke-affected wine in the wine blend, and thus smoke marker compounds. Research findings from both studies contribute to our understanding of grape smoke exposure and how it affects wine quality as determined by instrumental measurements, wine experts, and non-experts.

    Funding Support: Jackson Family Wines, USDA-ARS

    Jenna Fryer | Elizabeth Tomasino

    The Efficacy of Common Winemaking Practices on Reducing Wildfire-Smoke Flavor Perception in Cabernet Sauvignon Wines

    Jenna Fryer and Elizabeth Tomasino*
    *Oregon State University, 3051 SW Campus Way, Corvallis, OR, 97331 (elizabeth.tomasino@oregonstate.edu)

    With the increasing frequency of wildfires in wine-producing regions around the world, wine producers are looking for strategies to reduce the sensory impact that these fires have on wine. Wines produced from smoke-exposed grapes have been found to have smokey, burnt, and dirty aromas and flavors, along with a distinctive lingering ashy finish. Several mitigation strategies have been studied to determine their level of efficacy in reducing the effect of wildfires on wines, looking at both chemical composition and sensory alterations. This study further evaluated the influences of common winemaking practices on the sensory properties of wildfire-affected wines. Using descriptive analysis of Cabernet Sauvignon wines, blending, carbon fining, SRX resin treatment, oak chips, and differing oak barrel usage were all evaluated. The results indicated that blending did not consistently reduce smoke flavor perception as the percentage of smoke-affected wine in the blend was reduced. The resin treatment showed more promise for reducing smoke flavors than the carbon treatment. For oak, differences based on oak origin were observed, with greater intensities of smoke flavors with French oak than American oak. Finally, this study showed that from a sensory perspective, there was no carryover of smoke flavors from used barrels that previously held smoke-affected wine. Overall, this work showed that common winemaking practices can effectively reduce the effect of wildfire on wines; however, further trials must determine what provides the most benefit for a specific vintage. This work helps increase our knowledge of the sensory alterations that wildfires cause and how widely used winemaking practices affect wine sensory properties. With this knowledge, sensory-guided decisions can be made on what strategies to employ in future wildfire years.

    Funding Support: USDA-SCRI grant no. 2021-51181-35862/project accession no. 1027470

    Read more: Enology – Sensory of Grapes and Wine Session
  • Enology – Microbiology Session Research Reports

    June 19, 2024 – 1:30pm – 3:30pm

    Research Reports

    Location: Marriott Portland Downtown Waterfront

    Moderator:

    Torey Arvik, Arvik & Associates, California

    Speakers:

    1:30 pm – 1:50 pmDigging deeper into Microbial Terroir: Biogeography of Hanseniaspora in Oregon’s Willamette Valley Wine Region
    Tess Snyder, Oregon State University, Corvallis
    1:50 pm – 2:10 pmSaccharomycodes ludwigii Yeast Derivatives: Novel Potential Bio-Adjuvants for the Winemaking Process
    Paola Domizio, Universita’ Studi di Firenze, Italy
    2:10 pm – 2:30 pmEffect of Malolactic Fermentation Timing and Cold Soaking with Torulaspora delbrueckii on Pinot noir Sensory Properties
    Matt Garcia, Oregon State University, Corvallis
    2:30 pm – 2:50 pmRevealing Aromatic Thiols in Red Wines
    Jessica Noble, Lallemand Oenology, France
    2:50 pm – 3:10 pmIs Complex Nutrition More Advantageous than Mineral Nitrogen for the Fermentative Capacity of Saccharomyces cerevisiae?
    Stéphanie Rollero, Fermentis, France
    3:10 pm – 3:30 pmEffect of Pediococcus on Wine Chemical and Sensory Properties
    Esther Wanjohi, Oregon State University, Corvallis

    Tess Snyder | Jacob Martin | Bjarne Bartlett | James Osborne | Chris Curtin

    Digging deeper into Microbial Terroir: Biogeography of Hanseniaspora in Oregon’s Willamette Valley Wine Region

    Tess Snyder, Jacob Martin, Bjarne Bartlett, James Osborne, and Chris Curtin*
    *Oregon State University – Department of Food Science and Technology, 100 Wiegand Hall, Corvallis, OR, 97331 (christopher.curtin@oregonstate.edu)

    The apiculate yeast genus Hanseniaspora has appeared frequently in enological research for over a century, mostly focused upon the species Hanseniaspora uvarum because of its notable capacity to cause spoilage. Recently, there has been more research into the potential benefits of other Hanseniaspora species, such as Hanseniaspora vineae, in producing more complex wines. Furthermore, large-scale, DNA sequencing-based (metabarcoding) vineyard ecology studies have suggested that Hanseniaspora species may not be evenly distributed. Does this mean that fruit from different vineyards could yield spoiled or complex wines depending on which Hanseniaspora species are present? To address this, we sampled extensively from 12 vineyards within the Willamette Valley AVA, across two sub-AVAs (Eola and Yamhill). We then used metabarcoding to assess the contribution of Hanseniaspora to the grape berry fungal community and their relative abundance in cold-soak and early stages of fermentation.

    Our results show that while six of the 23 recognized Hanseniaspora species were present on Pinot noir grapes in the Willamette Valley AVA, differences between vineyards were driven by the abundance of H. uvarum. On the other hand, fungal community differences between sub-AVAs were not related to Hanseniaspora species. We observed significant positive correlation between the amount of H. uvarum present in must and at cold-soak, and then cold-soak to early fermentation. While intuitive, it is worth noting that no prior studies have observed this across so many grape samples from different vineyards. Our results provide clear evidence that the amount of H. uvarum on grapes may be an important predictor of potential effects on wine quality, particularly if performing cold-soak, which acts as an enrichment step. H. uvarum isolates have been recovered from almost every must sample for whole genome sequencing and are being evaluated for genetic and phenotypic differences to determine whether vineyard and/or sub-AVA populations vary.

    Funding Support: Oregon Wine Research Institute, Agricultural Research Foundation and Oregon State University

    Valentina Civa | Marco Ongaro | Matteo Bosaro | Paolo Antoniali | Paola Domizio

    Saccharomycodes ludwigii Yeast Derivatives: Novel Potential Bio-Adjuvants for the Winemaking Process

    Valentina Civa, Marco Ongaro, Matteo Bosaro, Paolo Antoniali, and Paola Domizio*
    *Universita’ Studi di Firenze, Via Donizetti, Firenze, 50144, Italy 
    (paola.domizio@unifi.it)

    To promote more sustainable production methods and greater respect for the natural characteristics of wines, this study evaluated the impact of non-conventional yeast derivatives on the chemical and physical properties of wines. In particular, various types of yeast derivatives obtained from Saccharomycodes ludwigii were used. This is an osmophilic yeast whose affect on wine has so far been evaluated only as a function of its metabolic activity. However, recent studies have indicated that yeasts belonging to the Saccharomycodes genus can release significant amounts of polysaccharides, particularly mannoproteins, into the medium both during growth and after inactivation. These macromolecules are known to interact with various compounds in wine, contributing to its colloidal stability. Thus, after optimizing the growth conditions favoring production of S. ludwigii biomass, innovative techniques for yeast inactivation were employed and the effect of different derivatives on the final chemical and physical characteristics of white wine was assessed. All fermentation tests conducted with S. ludwigii derivatives exhibited better fermentation kinetics than the control. Basic parameters were consistent across all wines. However, there were significant differences in the aromatic profiles. Wines treated with S. ludwigii derivatives showed higher polysaccharide content compared to the control. Further analysis is warranted to evaluate the influence of these macromolecules on wine colloidal stability and sensory characteristics over time.

    Funding Support: Enartis

    Matt Garcia | James Osborne | Elizabeth Tomasino

    Effect of Malolactic Fermentation Timing and Cold Soaking with Torulaspora delbrueckii on Pinot noir Sensory Properties

    Matt Garcia,* James Osborne, and Elizabeth Tomasino
    *Oregon State University, 421 NW 4th St, Apt B, Corvallis, OR, 97330 (matthew.garcia@oregonstate.edu)

    This study investigated the influence of malolactic fermentation (MLF) timing on Pinot noir color and sensory properties. The addition of a non-Saccharomyces yeast, Torulaspora delbrueckii, during cold soak was also investigated due to potential interactions with the malolactic bacteria and production of acetaldehyde. Pinot noir wines were produced with and without cold soaking, with and without T. delbrueckii, and with a concurrent or sequential MLF. Cold soaking with T. delbrueckii yielded higher acetaldehyde concentrations at the end of cold soak and during alcoholic fermentation, but did not result in significant color differences at the end of MLF. Concurrent MLFs decreased color density and polymeric pigment content, but only if a cold soak had also been undertaken. After nine months of aging, differences in wine color and polymeric pigment content noted at the end of MLF were no longer present. Wines were assessed by a sensory panel to determine liking and sensory characteristics. Panelists were asked to rate their liking of each wine in clear and opaque glasses and to complete rate-all-that-apply descriptive analyses for aroma, taste, and mouthfeel. Wines produced without cold soaking had a significantly different aroma than those produced with a cold soak, while non-cold soak wines were significantly different from each other due to MLF timing. When not paired with cold soak, the concurrent MLF wine was described as having woody and spiced aromas, while the sequential MLF wine was described as having cedar, fruity, and herbal aromas. Use of T. delbrueckii during cold soaking resulted in wines described as having a more balanced and softer mouthfeel than their counterparts. Overall, MLF timing did not affect color once wines had been aged, but did result in wines with different aroma and mouthfeel properties. Cold soaking and use of T. delbrueckii also resulted in wine sensory changes.

    Funding Support: Oregon Wine Board, American Vineyard Foundation

    Jessica Noble | Marion Bastien | Anthony Silvano | Anne Ortiz-Julien

    Revealing Aromatic Thiols in Red Wines

    Jessica Noble,* Marion Bastien, Anthony Silvano, and Anne Ortiz-Julien
    *Lalemand Oenology, 19 Rue des Briquetiers, 31702 Blagnac, France 
    (jnoble@lallemand.com)

    Volatile thiols are a well-known family of aroma compounds that, even at low levels, can have a significant affect on the fruity quality of wines. 3MH, 3MH-A, and 4MMP are some of the more well-known aromatic thiols. These compounds confer grapefruit, passion fruit, and boxwood notes in thiolic white and rosé wines when revealed from their odorless form. However, thiol precursors are now known to be present in important red grape cultivars (e.g., Syrah, Cabernet Sauvignon, Merlot, Pinot noir). When revealed, the descriptors used to describe the same thiolic compounds in red wines are black fruits, red fruits, and spice. The aromatic profile of thiols in red wines is complex and is thought to be due to interactions between thiols and other molecules, such as terpenes and esters.

    The enzymatic action of yeast is essential to cleave the non-volatile, odorless precursors and release the volatile, aromatically active thiols. Using a cell division approach, we selected a new Saccharomyces yeast with the full potential for thiol revelation due to its highly efficient β-lyase enzyme activity. This enzyme activity is due to the yeast possessing the correct form of the IRC7 gene. The sequence of the IRC7 gene is not identical among all yeasts. Some yeasts have a truncated version of this gene, missing 38 base pairs. This version encodes a non-functional enzyme. Other strains can have a point mutation, close to the enzyme’s active site, which has a strong negative effect on its activity.

    For maximum β-lyase activity, the yeast must possess the right combination of the gene, which is the long, unmutated form (IRC7L/L Ref/Ref). This new yeast strain shows very significant thiol revelation, well above average concentration, with a very significant increase in aromatic freshness and black and red fruit notes.

    Funding Support: Lallemand Oenology

    Stéphanie Rollero | Anne Flesch | Laura Chasseriaud | Etienne Dorignac | Marina Bely | Arnaud Delaherche

    Is Complex Nutrition More Advantageous than Mineral Nitrogen for the Fermentative Capacity of Saccharomyces cerevisiae?

    Stéphanie Rollero,* Anne Flesch, Laura Chasseriaud, Etienne Dorignac, Marina Bely, and Arnaud Delaherche
    *Fermentis, 137 Rue Gabriel Péri, 59700 Marcq-en-Baroeul, France 
    (s.rollero@fermentis.lesaffre.com)

    During alcoholic fermentation, nitrogen is an essential nutrient for yeast as it plays a key role in sugar transport and biosynthesis of wine aromatic compounds (thiols, esters, and higher alcohols). The main issue of a lack in yeast assimilable nitrogen (YAN) in winemaking is sluggish or stuck fermentations that promote growth of alterative species and lead to economic losses. However, correcting the N deficiency is sometimes not enough to restore proper fermentation performance. This suggests the existence of other nutritional shortages.

    The aim of this work was to study the effect of the timing and the nature of nutrient addition (mineral N [100% yeast derivative] or mixed complete [mineral N and yeast derivative]) on alcoholic fermentation. First, 16 commercial strains were inoculated into Sauvignon blanc grape must deficient in YAN (110 mgN/L) and with reducing sugars concentration adjusted to 240 g/L (potential alcohol content of 14.3% vol.). Fermentation kinetics of strains were then classified into three groups: stuck, sluggish, or complete alcoholic fermentations. New experiments were carried out in the same grape must supplemented in YAN with ammonium (mineral) or yeast derivative products (100% organic or mixed) to get 200 mgN/L. Nutrient additions were made at the beginning of alcoholic fermentation (single addition) or in two additions (50% at the beginning + 50% at the middle of alcoholic fermentation).

    Our results show that supplementation with mixed nutrients was more beneficial for fermentation performance than mineral N alone. Fractionated addition was also more effective than single addition. This study highlights the need to think about yeast nutrition from a holistic perspective (N and lipid addition, timing of addition).

    Funding Support: Fermentis, division of S.I. Lesaffre

    Esther Wanjohi | Elizabeth Tomasino | James Osborne

    Effect of Pediococcus on Wine Chemical and Sensory Properties

    Esther Wanjohi, Elizabeth Tomasino, and James Osborne*
    *Oregon State University, 3051 SW Campus Way, Corvallis, OR, 97331 
    (james.osborne@oregonstate.edu)

    Pediococci have been isolated from wines worldwide, but their specific effect on wine quality is not well described. Due to warmer growing seasons leading to higher-pH grapes and winemakers looking to reduce sulfur dioxide (SO2) use, the risk of Pediococci growth in wines is increasing. Therefore, this project aimed to characterize the sensory impact of Pediococcus on wine and investigated the effect of wine lees and nutrient additions on biogenic amine (BA) production. Nineteen Pediococcus isolates from Oregon, Washington, and California wines were inoculated into sterile filtered Pinot noir and growth was observed for 56 days, followed by the addition of SO2 and bottling. Differences in growth were observed, with many isolates maintaining a population similar to the initial inoculation rate (105 CFU/mL), while others declined in viability before recovering to higher populations. Experienced wine tasters using a modified napping method and ultra-flash profiling assessed the wines. No strong groupings of treatments based on aroma were observed, but there were two distinct groupings based on mouthfeel. One grouping was described as “Light,” “Thin,” and “Sharp,” while the other group was described as “Sticky,” “Medium,” and “Sharp.” These descriptors will be used to define additional chemical analysis. To explore factors affecting BA production by Pediococcus, different nutrient additions were made to Chardonnay juice prior to fermentation. The three nutrient addition treatments were control, high DAP, and high organic N. After completion of alcoholic fermentation, wines were cold-settled prior to racking (no-lees) or no racking (lees) treatments. Dimethyl-dicarbonate was added to kill background microorganisms and after 48 hrs, two BA-producing Pediococcus strains were inoculated into the wines. Growth was monitored for 60 days, after which samples were collected for analysis. BA will be assessed by liquid chromatography-mass spectrometry to determine the effect of nutrients and lees aging on BA production by Pediococcus.

    Funding Support: This works was funded by the Northwest Center for Small Fruits Research (59-2072-1-008)

    Read more: Enology – Microbiology Session Research Reports