Date: June 2020
Project Title: Sensory Characteristics of Washington State Wines
Project Duration: 3 years
Principal Investigator: Carolyn F. Ross,
Organization: School of Food Science, Washington State University, Pullman, WA 99164-6378
Email: cfross@wsu.edu; Phone: 509) 335-2438
Collaborator(s): Charles Edwards
Organization: School of Food Science, Washington State University, Pullman WA
Participation: wine microbiology and wine chemistry
Collaborator(s): Jungmin Lee
Organization: USDA-ARS-HCRU (Corvallis, OR) worksite (Parma, ID), WSU School of Food Science affiliate faculty Participation: wine analyses
Summary:
Over the past decades, a trend in the wine industry has been higher alcohol wine. To address the associated challenges with high alcohol wines, microbiological strategies are helpful. The use of wine yeast to produce wine with reduced alcohol remains one of the simplest strategies for winemakers to implement. As determined using instrumental analyses, previous studies have demonstrated that the use of non-Saccharomyces yeasts modifies the volatile profile of the wine. However, mouthfeel may also be affected due to the phenomenon of pectin breakdown induced by these yeasts due to their production of pectinase. However, the full influence of these non-Saccharomyces yeast strains on the final sensory quality remains unknown. Therefore, the overall objective of this study was to examine the influence of different non-Saccharomyces yeasts on wine sensory and chemical attributes.
To investigate this objective, two studies were completed. In the first study, Chardonnay and Merlot were produced with either Saccharomyces cerevisiae (control) or a non-Saccharomyces yeast cocktail (Cr. adeliensis, I. orientalis, and P. kluyveri), with the addition S. cerevisiae after three days of fermentation. Pectin was added at 0.5 g/L to ensure sufficient substrate for the pectinase. In Chardonnay, pectin addition produced higher intensities of butter aroma and citrus flavors, increased floral and grassy aromas, along with increased sharpness and solvent flavor. Differences were also seen in the chemical analysis for Chardonnay, specifically in glycerol and galacturonic acid levels, which were highest in the non-Saccharomyces treatment with pectin and lowest in the Saccharomyces wine without pectin. In Merlot, the use of non-Saccharomyces yeasts produced wines with higher intensities of berry and dried fruit aromas, increased sharpness, as well as more intense berry, cherry, and geranium flavors. The addition of pectin also resulted in significant differences in viscosity and weight which related to the chemical components of galacturonic acid and glycerol levels. In addition, alcohol content was also significantly different, with pectin addition reducing alcohol.
In the second study, different pectin concentrations added to the wines during fermentation (Merlot: 0.25 – 1.25 g/L. Chardonnay: 0.25-1 g/L) were investigated. For Merlot, the addition of non-Saccharomyces yeasts was associated with notes of chocolate, berry, viscosity, drying and mouthcoating, with all treatments being similar except for the wine made with 1 g/L pectin. Merlot produced using non-Saccharomyces yeast with added 1 g/L pectin presented more animal, herbaceous and solvent aromas. The S. cerevisiae treatments were similar and described by their buttery and spicy flavor notes. For Chardonnay, the Saccharomyces treatments were related to attributes such as honey, melon and green apple. The Chardonnay treatments made with non-Saccharomyces treatments with higher pectin were associated with pear, woody and animal notes. The Chardonnay wines produced with lower concentrations of pectin with non-Saccharomyces were described by their green, and ethanol notes, with viscosity, and drying mouthfeel. These findings suggest that during fermentation, the use of non-Saccharomyces yeasts that produce pectinase, when sufficient substrate is present, may be useful in modifying wine quality.
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