Enology - Low Alcohol and Malolactic Fermentation Session

Holly Eaton | Jennifer Kelly | Debbie Inglis*

Optimizing Production Methods for Low-Alcohol Wine Using Fungus-Resistant Grape Varieties and Ontario Yeast Strains

Holly Eaton, Jennifer Kelly, and Debbie Inglis*

*Brock University, 1812 Sir Isaac Brock Way, St. Catherine’s, Ontario, L2S 3A1, Canada, dinglis@brocku.ca

Recent shifts in alcohol consumption trends have led to increased demand for low- and non-alcoholic beverages. In Ontario, Canada, consumers are seeking wines that are lighter, fruitier, and lower alcohol. In this study, we investigated different methods to reduce alcohol in wine, with focus on grape variety selection, use of indigenous yeast strains for fermentation, and using reverse osmosis postfermentation. Sustainable fungus-resistant grape varieties have recently been introduced to Ontario with favorable properties, including potential for producing high quality wines with reduced alcohol. Preharvest ripening data collected during the 2025 season for Sauvignon Rytos, Soreli, and Cabernet Volos indicated ripening patterns distinct from typical Vitis vinifera benchmarks, suggesting potential for achieving balanced maturity at lower sugar accumulation. Notably, Cabernet Volos was harvested at 11.4% potential alcohol, compared with 13.7% potential alcohol for Cabernet franc harvested from the same vineyard. Building on prior work with locally isolated Ontario yeast, musts from Soreli (white) and Cabernet Volos (red) were fermented using either a commercial Saccharomyces cerevisiae strain (control) or the local Saccharomyces uvarum strain CS-6, which has been associated with lower ethanol production. Across all fermentations, wines produced with CS-6 had significantly lower ethanol content compared to the control wines, with an average reduction of 0.5%. In addition, wines fermented with S. uvarum had higher glycerol content and generally trended towards reduced acetic acid production. To further explore methods for lowering alcohol content in wine, trials have been conducted using reverse osmosis postfermentation to selectively remove ethanol. This technology successfully reduced ethanol to target final concentrations, with measurable impacts on selected wine parameters (including acidity). Collectively, these results demonstrate a practical framework for producing lower-alcohol wines by combining variety selection, regionally derived yeast, and postfermentation dealcoholization.

Funding Support: Ontario Research Fund – Research Excellence

Zachary Bean | Amanda Fleming | Renee Threlfall*

Screening Fermentation Parameters of Commercial Non-Saccharomyces Yeast for Wine Production with Reduced Ethanol

Zachary Bean, Amanda Fleming, and Renee Threlfall*

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

With the consumption of no- and low-alcohol wines increasing worldwide, there is potential for using non-Saccharomyces yeast (NSY) to reduce ethanol through alternate metabolic pathways during wine production. Six commercial yeast strains (one Saccharomyces and five NSY), two aeration methods (none and air), and two replications were screened for reduced ethanol levels during Vignoles (Vitis hybrid) wine production. Five commercial strains of NSY, including three Metschnikowia pulcherrima (MP1, MP2, and MP3), one Metschnikowia fructicola (MF), and one Pichia kluyveri (PK), were compared to Saccharomyces cerevisiae (SC) as a control. Aeration occurred in the first 48 hr of fermentation for treatments with air (SC+Air, MP1+Air, MP2+Air, MP3+Air, MF+Air, and PK+Air). The NSY treatments were sequentially inoculated with SC 48 hr after NSY inoculation. Samples of juice/must were taken during fermentation at 21°C (0, 3, 6, 9, and 12 days) for analysis of organic acids, sugars, glycerol, and ethanol using high-performance liquid chromatography. On day 0, total sugars of the juice were 19.42%. All treatments completed fermentation (total sugars <0.3%) by day 10, with SC and SC+Air treatments completing fermentation prior to NSY treatments. At day 12, ethanol ranged from 10.84 to 11.38%, with SC and SC+Air treatments producing 11.14% and 10.96% ethanol, respectively, while PK (11.38%) and PK+Air (11.28%) had highest ethanol and MP2+Air (10.84%) had the lowest. In addition, at day 12, air reduced ethanol production for all MP strains. Fermentation treatments with less ethanol than SC at day 12 included SC+Air (-0.18%), MP1+Air (-0.21%), MP2+Air (-0.30%), MP3+Air (-0.21%), MF (-0.01%), and MF+Air (-0.15%). The NSY strains with the greatest ethanol reduction in this study (MP1, MP2, MP3, and MF) will be evaluated for larger scale wine production using United States native and hybrid grapes.

Funding Support: none

Managing Malolactic Fermentation to Drive Changes in Pinot noir Wine Characteristics

Nicholas C Mannino, Lindsay Garcia, Darrell Cerrato, Camilla Satori, Elizabeth Tomasino,
and James P Osborne*

*Oregon State University, 100 Wiegand Hall, RM 108, Corvallis, OR, 97331-8575, James.Osborne@oregonstate.edu

Malolactic fermentation (MLF) is a key step in producing cool-climate red wines such as Pinot noir. While deacidification is the primary purpose of MLF, the process also alters wine aroma, flavor, and mouthfeel and is influenced by several factors. This study evaluated the combined effects of ML strain, MLF timing, and prefermentation nutrient additions on the fermentation kinetics, chemical composition, and sensory characteristics of Oregon Pinot noir wine produced in 2024 and 2025. In both years, MLF timing influenced MLF kinetics, tannin content, and color development. Compared with co-inoculation, sequential MLF inoculation consistently increased polymeric pigment formation at the end of MLF and after aging. Differences in protein-precipitable tannin were observed after MLF for ML strain and MLF timing treatments. However, these differences were no longer present after aging. Hunter Lab L*, a*, and b* color values differed at the end of MLF across all treatments, and these shifts continued during aging. Wines were assessed for volatile aroma composition using headspace solid-phase microextraction coupled to gas chromatography-tandem mass spectrometry. Wine aroma composition differed significantly as a function of MLF timing, strain, and vintage. Despite analytical differences, trained consumer sensory evaluation of 2024 wines showed limited discrimination among treatments, suggesting that subtle fermentation-driven aroma differences may fall below the resolution of trained consumer panels. Ongoing work compares volatile aroma data with results from an expert winemaker sensory panel to assess whether professional tasting expertise provides greater sensitivity to aroma variation linked to MLF management. Collectively, the results demonstrate that altering MLF timing and ML strain can affect Pinot noir wine properties. Understanding these effects could help winemakers optimize MLF management to achieve desired wine styles.

Funding Support: Oregon Wine Board #2024-2870

9:10 am – 9:30 am	Optimizing Production Methods for Low-Alcohol Wine Using Fungus-Resistant Grape Varieties and Ontario Yeast Strains Holly Eaton, Brock University, Canada
9:30 am – 9:50 am	Screening Fermentation Parameters of Commercial Non-Saccharomyces Yeast for Wine Production with Reduced Ethanol Zachary Bean, University of Arkansas, Fayetteville
9:50 am – 10:10 am	Managing Malolactic Fermentation to Drive Changes in Pinot noir Wine Characteristics Nicholas C Mannino, Oregon State University, Corvallis

Enology – Low Alcohol and Malolactic Fermentation Session

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