Enology – Microbial Impacts in Winemaking and Cellar Management Session

June 19, 2025 – 1:10 pm – 2:30 pm

Research Reports

Location: Portola Hotel, Monterey, California

Moderator:

To be announced

Speakers:

1:10 pm – 1:30 pm	CIP Implementation in Wineries to Reduce Water and Chemical Use Brooke Fanale, University of California, Davis
1:30 pm – 1:50 pm	Modulation of Malic Acid by Saccharomyces cerevisiae Strains: Development of Novel Acidifying Starters Ana Hranilovic, Laffort, France
1:50 pm – 2:10 pm	Impact of Different Strains of Lachancea thermotolerans Yeast on Acids and Sugars during Chambourcin Wine Fermentations Renee Threlfall, University of Arkansas, Fayetteville
2:10 pm – 2:30 pm	Impact of Nutrient Additions and Wine Lees on Biogenic amine Production by Pediococcus James Osborne, Oregon State University, Corvallis

Brooke Fanale* | David Block | Robert Coleman | Ron Runnebaum

CIP Implementation in Wineries to Reduce Water and Chemical Use

Brooke Fanale,* David Block, Robert Coleman and Ron Runnebaum

*UC Davis, 1 Shields Ave, Davis, CA, 95616, bmfanale@ucdavis.edu

Reduction in water and cleaning chemistry use has become essential in the wine industry, given water scarcity and the cost of wastewater treatment. Clean-in-Place (CIP) technology, using a central fixed in place cleaning system, is a potential solution. In other allied industries such as dairy processing, biopharma, and brewing, CIP has been able to reduce the use of cleaning chemistries and water, while automating cleaning to reduce labor and improve worker safety—all while improving cleaning. This study examined incorporating CIP systems into the wine industry, focusing on fermentation and storage vessels, where automated cleaning has not yet been widely incorporated but represents a significant portion of resource allocation. This was accomplished by examining hydrocyclones, understanding CIP wastewater composition, and assessing nanofiltration for recycling of cleaning chemistries and water. Hydrocyclones, a potential economical and energy-efficient option to remove relatively small particle solid waste from liquid streams, were assessed in single stages and in series to determine the recovery of solids. Wine lees collected from white fermentation tanks were used, allowing assessment of the necessity for further clarification prior to water re-use. Composition of cleaning wastewater produced in a winery (i.e., typical “dirt”) was also examined to understand what is typical. Samples were collected on six 2000-L tanks during typical cleaning cycles using the installed CIP system. Samples were taken at each stage of cleaning at the tank inlet and outlet and examined using a combination of high-performance liquid chromatography, Lowry protein assay, and potassium probe to quantify levels of acids, sugars, alcohols, protein, potassium, and polysaccharides expected to be present in a postfermentation wine tank. With alternative cleaning chemistries (potassium hydroxide, hydrogen peroxide, and potassium bisulfate), nanofiltration of the cleaning solutions was evaluated. Up to 95% of the cleaning solutions could be recovered.

Funding Support: UC Davis, Foley Family, and Treasury Wine Estates

Modulation of Malic Acid by Saccharomyces cerevisiae Strains: Development of Novel Acidifying Starters

Ana Hranilovic,* Charlotte Vion, Julia Capitanio, Chantal Mansour, Margaux Bernard, Maitena Muro, Philippe Marullo and Joana Coulon

*Laffort, 11 Rue Aristide Berges, Floirac, 33270, France, ana.hranilovic@laffort.com

Insufficient acidity in grapes due to warming climates requires costly adjustments throughout winemaking. During alcoholic fermentation (AF), acidity can be reduced further by yeast metabolism, as most Saccharomyces cerevisiae strains partially consume malic acid. This study describes the development of novel S. cerevisiae strains capable of producing malic acid through QTL-assisted breeding. The resulting ‘ACIDIC’ strains produced >3 g/L malic acid under winemaking conditions, leading to pH reductions exceeding 0.5 units. In parallel, a distinct group of ‘DEMAL’ strains capable of consuming up to 80% of the initial malic acid was obtained. Extensive phenotypic characterization, in terms of fermentation performance, production of primary and secondary metabolites, and sensory effect, highlighted the ability of these strains to modulate wine acidity under various enological conditions. It also delivered two starters for broader application in the wine industry, which were further evaluated in a series of winemaking trials. Detailed chemical and sensory profiling of the obtained wines validated their acidifying capacity, with increased malic acid post-AF and/or lactic acid post-FML (up to 1 g/L and 0.7 g/L, respectively). The decreased pH and increased titratable acidity were in line with the yeast-derived modulation of malic acid and accompanied by lower ethanol content (<0.5% vol.) and enhanced glycerol production. Analysis of yeast-derived flavor compounds further revealed distinct metabolic fingerprints, contributing to an overall ‘fresher’ wine profile. Together, these findings broaden the intrinsic capacity of S. cerevisiae to modulate malic acid during fermentation, provide insights into the underlying regulatory mechanisms, and offer new microbial tools to manage acidity and differentiate wine styles.

Funding Support: Laffort

Renee Threlfall* | Amanda Flemming

Effect of Different Strains of Lachancea thermotolerans Yeast on Acids and Sugars during Chambourcin Wine Fermentations

Renee Threlfall* and Amanda Flemming

*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 to enhance wine complexity and resolve acidity issues. In 2023, 252 kg of Arkansas-grown Chambourcin (Vitis hybrid) grapes were hand-harvested, randomized into batches, crushed, and destemmed. Seven inoculation treatments were conducted in duplicate using Saccharomyces cerevisiae (SC) and three strains of L. thermotolerans,including a commercial strain (LAK) and two experimental strains (LT₁and LT₂). L. thermotolerans treatments received sequential S. cerevisiae inoculations after 24 or 48 hr. All treatments were co-inoculated with malolactic bacteria 24 hr after S. cerevisiae. Total sugars, pH, titratable acidity (TA), and total organic acids of the grapes/must/wines were evaluated during fermentation at 21°C (0, 3, 6, 9, and 12 days) and at bottling.At harvest, grapes had 20.36% total sugars, pH 3.77, 0.61% TA, 0.37% malic acid, and 1.19% total organic acids. All treatments completed alcoholic fermentation by day 6 (total sugars < 0.3%), though by day 3 SC wines finished. At day 3, lactic acid ranged from 0.22% (LAK-SC-24 hr) to 0.42% (LT₁-SC-48 hr). By day 6, SC wines had the highest pH (3.89), while other treatments ranged from 3.58 to 3.74. By day 12, LT₂-SC-48 hr wines had the highest TA (0.84%) and lactic acid (0.35%), while malic acid remained slightly unfinished in all wines (0.04 to 0.06%). At bottling, SC wines had the highest pH (4.00), while other treatments ranged from 3.82 to 3.87. LT₁-SC-48 and LT₂-SC-48 wines had the highest lactic acid (0.43 to 0.46%) and total organic acids (0.91 to 0.92%) compared to SC wines (0.25% and 0.72%, respectively). L. thermotolerans strainsin mixed inoculation with S. cerevisiae produced Chambourcin wines with lower pH and higher TA and lactic acid. This fermentation approach offers a natural way to enhance acidity, stabilize microbial balance, and address winemaking challenges in warm-climate regions.

Funding Support: Lallemand Oenology

Jaewoo Choi | Liping Yang | James Osborne*

Effect of Nutrient Additions and Wine Lees on Biogenic Amine Production by Pediococcus

Jaewoo Choi, Liping Yang and James Osborne*

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

This study investigated the effect of wine lees and nutrient additions on biogenic amine production by Pediococcus. Initial experiments assessed production of biogenic amines by Pediococcus in Merlot, Pinot noir, and Chardonnay wine. Of the four isolates tested, only Pediococcus inopinatus OW8 increased the concentration of biogenic amines, with all wines into which OW8 was inoculated containing significantly higher histamine than the control wine. Differences between wines were also noted. Pinot noir wines inoculated with OW8 contained the most histamine, followed by Merlot and then Chardonnay. The lower histamine concentration in Chardonnay wine may have been due to the initial slower growth of P. inopinatus OW8 in this wine compared to Merlot and Pinot noir. However, P. inopinatus populations still reached >10⁷ CFU/mL in the Chardonnay wine. Additional factors that could affect biogenic amines were also explored. Three different nutrient treatments were applied to a Chardonnay juice prior to fermentation. The three treatments were control, high diammonium phosphate (DAP), and high organic N. After completion of alcoholic fermentation, wines were cold-settled and dimethyl-dicarbonate was added to eliminate background microorganisms. After cold settling, wines were racked or not racked to create lees or no lees treatments and either P. inopinatus OW8 or Pediococcus parvulus WS9 was inoculated into the wines. Nutrient addition and lees treatments significantly affected the concentration of biogenic amines in the wine. The addition of either organic nutrients or DAP resulted in significantly higher histamine in treatments inoculated with P. inopinatus OW8. DAP additions resulted in significantly more histamine than organic nutrients.Aging on the lees also increased production of histamine by P. inopinatus OW8, but only if nutrients had been added. Overall, the addition of DAP and aging on lees resulted in the greatest concentration of histamine in treatments inoculated with Pediococcus.

Funding Support: Northwest Center for Small Fruits Research