Dissertation
The Sensory and Chemical Properties of Wines as Influenced by the Presence of Different Wine Bacteria and Yeasts
Washington State University
Doctor of Philosophy (PhD), Washington State University
01/2021
DOI:
https://doi.org/10.7273/000005500
Handle:
https://hdl.handle.net/2376/119240
Abstract
Wine quality is a complex concept that is greatly influenced by its sensory characteristics and chemical composition, and many factors can contribute or detract from quality. The overall objective of this dissertation was to examine microbiological factors and their influence on wine quality using sensory evaluation and analytical testing methods. In the first study, the ability of the electronic tongue and experienced sensory panelists to discriminate among wines inoculated with spoilage microorganisms over storage was evaluated. Merlot wine was inoculated with spoilage microorganisms, in particular Brettanomyces bruxellensis, Pediococcus parvulus, Acetobacter pasteurianus, and Lactobacillus brevis, and tested weekly. Results showed that the electronic tongue discriminated among the inoculated wine samples starting at Day 21 of storage, while the experienced sensory panelists were unable to discriminate until Day 28. Therefore, the electronic tongue was demonstrated to be a useful tool for early detection of wine faults. In the second study, the influence of storage on the sensory and chemical characteristics of wines made with pectinase-producing non-Saccharomyces yeasts (NSY). The addition of NSY in Merlot wine increased cherry flavor over storage (p ≤ 0.05), an attribute often associated with wine quality. Additionally, significant differences were observed in pH and glycerol concentration in the wine. Some NSY that produce pectinase have been shown to increase polysaccharide concentrations which can improve mouthfeel characteristics. Building on this, providing sufficient substrate (pectin) may increase the activity of this enzyme. Therefore, the final study evaluated the influence of pectinase producing NSY on the sensory and chemical characteristics of wined with varying amounts of pectin. In both red and white wine, significant differences (p ≤ 0.05) were observed in the chemical parameters, in particular pH and D-galacturonic acid; however minimal differences were found in the sensory characteristics. Overall, this research advanced the understanding of how wine quality is affected by different wine microorganisms. In particular, new sensory and analytical methods for more rapid wine fault detection were developed, and a deeper understanding of the potential utilization of pectinase producing NSY to elicit chemical and sensory change was found.
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Details
- Title
- The Sensory and Chemical Properties of Wines as Influenced by the Presence of Different Wine Bacteria and Yeasts
- Creators
- Victoria Paup
- Contributors
- Carolyn F Ross (Advisor)Charles G Edwards (Committee Member)Charles Diako (Committee Member)Jungmin Lee (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- School of Food Science
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Publisher
- Washington State University
- Number of pages
- 155
- Identifiers
- 99900592360201842
- Language
- English
- Resource Type
- Dissertation