Thesis
Factors Influencing the Growth of Brettanomyces Bruxellensis in Red Wine
Washington State University
Master of Science (MS), Washington State University
2023
DOI:
https://doi.org/10.7273/000006317
Abstract
Brettanomyces bruxellensis is a yeast that continues to be a large threat to the production of quality red wine due to its ability to generate volatile phenols, acetic acid, and other off- flavors in finished wine. To help reduce risk of contamination outcomes, the main and interactive effects of molecular SO2, ethanol, and storage temperature on B. bruxellensis growth and spoilage compound synthesis were measured. A 4x2x2 factorial experiment was designed with mSO2 (0. 0.2, 0.4, or 0.8 mg/L), ethanol (13.5% or 14.5% v/v), and storage temperature (12° or 18°C) as variables in a commercial red wine. B. bruxellensis populations were eliminated when 0.4 or 0.8 mg/L mSO2 was added to wine at every temperature and ethanol concentration and no further growth was seen. Surviving and increasing populations were only observed at 0.2 mg/L SO2, 18°C, and 13.5% ethanol on days 55, 71, 76, and 90, but on no other days tested. Concentrations of volatile phenols above the sensory threshold were produced only in wines that contained no SO2. In addition, the rate of reduction of mSO2 was analyzed by measuring the concentration of each SO2 level every other week for 90 days for each of the various conditions described above. The rates of mSO2 depletion were significantly faster at the 0.8 mg/L concentration and slower 12°C while ethanol concentrations had no effect. Finally, the effect of wine matrix variation on B. bruxellensis was also investigated. Several commercially produced wines from various wineries were blended into different ratios or had further nutrients (synthetic wine blend and p-coumaric acid) added to create several different wine compositions to which B. bruxellensis I1a was inoculated. With other variables remaining the same (e.g., mSO2 concentration, temperature, pH, etc.) wine 1 had no B. bruxellensis growth and instead saw a significant rapid decline in numbers while wine 5 and wines with >10% wine 2 had extended lag phases and failed to generate spoilage compounds above sensory threshold levels. Further research is needed to determine the unidentified inhibitory factors that cause this effect.
Metrics
Details
- Title
- Factors Influencing the Growth of Brettanomyces Bruxellensis in Red Wine
- Creators
- Summer A Dietsche
- Contributors
- Carolyn Bohach (Advisor)Thuy Bernhard (Advisor)Luying Xun (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- School of Food Science
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University
- Number of pages
- 82
- Identifiers
- 99901086722901842
- Language
- English
- Resource Type
- Thesis