Thesis
Effects of 4-ethylphenol and 4-ethylguaiacol on the sensory properties of Washington state Cabernet Sauvignon and Syrah
Washington State University
Master of Science (MS), Washington State University
2011
Handle:
https://hdl.handle.net/2376/102159
Abstract
Brettanomyces bruxellensis is a spoilage yeast commonly associated with increased concentrations of 4-ethylphenol (4-EP) and 4-ethylguaiacol (4-EG) in wine. The objective of this study was to determine the sensory effect of Brettanomcyes bruxellensis- associated compounds in WA State Syrah and Cabernet Sauvignon. First, the consumer preference of 4-EG and 4-EP in WA State Syrah and Cabernet Sauvignon was determined. Four consumer panels (n=50) were conducted that evaluated six ratios of 4-EG to 4-EP: 1:2 (100µg/L 4-EG: 200µg/L 4-EP), 1:5 (100µg/L 4-EG: 500µg/L 4-EP), 1:10 (100µg/L 4-EG: 1000µg/L 4-EP) and 1:4 (100µg/L 4-EG: 400µg/L 4-EP), 1:8 (100µg/L 4-EG: 800µg/L 4-EP) and 1:12 (100µg/L 4-EG: 1200µg/L 4-EP), and compared preference against a control wine. For Cabernet Sauvignon, significant decreases in consumer preference were observed at the 1:5, 1:8 and 1:12 ratios. For Syrah, significant decreases in consumer preference were observed at the 1:5, 1:8, 1:10 and 1:12 ratios. A difference from control test was the conducted using the same wines and 4-EG:4-EP ratios of 1:4, 1:8 and 1:12. Consumers identified the Syrah control wine as significantly different from all three spiked wines; no significant differences were perceived for Cabernet Sauvignon. Next, the sensory and chemical impact of Biotan® , a grape seed tannin, on 4-EG and 4-EP perception in WA State Syrah and Cabernet Sauvignon was determined. Biotan® was added to v both wines containing a 1:8 ratio of 4-EG:4-EP, at 500, 1000 and 1500 mg/L catechin equivalents. A trained panel evaluated wines for medicinal, spicy, leather and fruity aroma intensity. In Cabernet Sauvignon, tannin concentration increased medicinal and lowered fruity aroma intensity (p<0.05). No significant differences were observed in Syrah. From analytical determinations, results indicated that tannin addition impacted the concentration of 4-EP in the wine headspace. Overall, 4-EG and 4-EP were capable of altering the sensory characteristics of WA State red wines, resulting in decreased consumer preference of the wine. However, the wine matrix, specifically tannin profile, may influence the impact of these compounds.
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Details
- Title
- Effects of 4-ethylphenol and 4-ethylguaiacol on the sensory properties of Washington state Cabernet Sauvignon and Syrah
- Creators
- Sarah Michaux
- Contributors
- Carolyn F. Ross (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, Wash. :
- Identifiers
- 99900525273801842
- Language
- English
- Resource Type
- Thesis