Dissertation
Use of Non-Saccharomyces Yeasts for Reducing the Ethanol Contents of Red Wine
Washington State University
Doctor of Philosophy (PhD), Washington State University
12/2019
DOI:
https://doi.org/10.7273/000005559
Abstract
Yeasts isolated from Washington vineyards were investigated for their abilities to reduce alcohol contents of red wines. An initial evaluation of carbohydrate and nitrogen utilization was conducted in high sugar (>300 g/L glucose and fructose) grape musts using four non-Saccharomyces yeasts (Candida californica, Metschnikowia pulcherrima, Meyerozyma caribbica, and Wickerhamomyces anomalus). When inoculated into Syrah grape must six days prior to S. cerevisiae, non-Saccharomyces yeasts influenced concentrations of glycerol and volatile aromas, and lower concentrations of ethanol were observed in ferments with C. californica and Mt. pulcherrima. In a broader screening, 16 species of non-Saccharomyces yeasts were investigated for their ability to metabolize sugar without ethanol production when inoculated into Merlot must (310 g/L glucose and fructose) six days before S. cerevisiae without and with added oxygen. Five species (Mt. chrysoperlae, Mt. pulcherrima, My. guilliermondii, Pichia kluyveri, and P. membranifaciens) produced wines with significantly less ethanol without excessive acetic acid accumulation. When inoculated into Merlot must containing less sugar (266 g/L glucose and fructose) three days prior to S. cerevisiae, dry wines (?? 2 g/L glucose and fructose) with significantly less ethanol were obtained using Mt. pulcherrima and My. guilliermondii. Synthetic media sequentially inoculated with Mt. pulcherrima then S. cerevisiae, which contained 2.4 to 3.0% less ethanol than cultures fermented with S. cerevisiae alone, confirmed lower ethanol production by Mt. pulcherrima. Conducting larger-scale fermentations (100 L) with unsterilized Merlot grape musts, wines with Mt. pulcherrima contained 0.9% v/v less ethanol than wines inoculated solely with S. cerevisiae. Finally, sensory evaluations were conducted on Merlot wines fermented under winery conditions with Mt. pulcherrima or My. guilliermondii yeasts. Mt. pulcherrima generated wines with 1.1% v/v less ethanol than wines fermented only with S. cerevisiae which were characterized by 'estery' and fruit-associated aromas and flavors. While My. guilliermondii did not affect ethanol content, wines fermented with this yeast exhibited 'berry' and 'woody' aromas and/or flavors with heightened astringency. Overall, this research demonstrates the potential to produce wines with lower alcohol content without compromising wine quality using Mt. pulcherrima isolated from Washington vineyards.
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Details
- Title
- Use of Non-Saccharomyces Yeasts for Reducing the Ethanol Contents of Red Wine
- Creators
- Jesse Joshua Aplin
- Contributors
- Charles G. Edwards (Chair)Carolyn Ross (Committee Member) - Washington State University, Food Science, School ofDojin Ryu (Committee Member) - Washington State University, Food Science, School ofJohn K Fellman (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Food Science, School of
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Publisher
- Washington State University
- Number of pages
- 141
- Identifiers
- 99901054232401842
- Language
- English
- Resource Type
- Dissertation