Thesis
Interactions between ethanol, storage temperature, and sulfur dioxide that affect Brettanomyces bruxellensis in Merlot wine
Washington State University
Master of Science (MS), Washington State University
2017
Handle:
https://hdl.handle.net/2376/101282
Abstract
Brettanomyces continues to be a spoilage problem in red wines. Compositional and environmental conditions that favor growth remain undefined. Using a commercially-prepared Merlot wine, a 5 × 4 factorial experimental design was employed with ethanol (12%, 13%, 14%, 15%, or 16% v/v) and temperature (12°, 15°, 18°, or 21°C) as variables. Culturabilities of two strains of B. bruxellensis isolated from Washington wines (I1a and F3) were monitored for 100 days before concentrations of volatile acidity (VA), 4-ethylphenol (4-EP), and 4-ethylguaiacol (4-EG) were measured. While growth was observed in 12% to 15% ethanol, lag phase duration generally increased with a decrease in temperature. Culturabilities quickly declined in wines containing 16% v/v ethanol, with rapid losses at 21°C. The two strains demonstrated similar growth patterns, except in wines containing 15% ethanol where F3 showed reduced growth at higher temperatures (18° and 21°C) compared to I1a. Wines in which Brettanomyces reached >106 cfu/mL had concentrations of 4-EP and 4-EG above sensory thresholds (440 µg/L and 47 µg/L, respectively). In a separate experiment, a 2 × 2 × 3 factorial design was employed with ethanol (13% or 14.5% v/v), temperature (15° or 18°C), and total SO2 (0, 60, or 100 mg/L) as variables. The addition of 100 mg/L total SO2 to wine resulted in inhibition of Brettanomyces growth in wine containing 14.5% v/v ethanol. It is therefore recommended that risk of spoilage associated with B. bruxellensis can be reduced through higher concentrations of ethanol, storage temperatures ≤12°C, or the addition of 100 mg/L total SO2 in wines containing ≥14.5% v/v ethanol.
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Details
- Title
- Interactions between ethanol, storage temperature, and sulfur dioxide that affect Brettanomyces bruxellensis in Merlot wine
- Creators
- Taylor Adam Oswald
- Contributors
- Charles G. Edwards (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Food Science, School of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; [Pullman, Washington] :
- Identifiers
- 99900525091501842
- Language
- English
- Resource Type
- Thesis