Thesis
Compositional Changes of Smoke-Derived Volatile Phenols and Their Glycoconjugates in Wine During Acid Hydrolysis
Washington State University
Master of Science (MS), Washington State University
2023
DOI:
https://doi.org/10.7273/000005189
Abstract
Smoke taint is a leading issue for the global wine industry as wildfires have become common in grape-growing regions worldwide in recent years. There is a demand for reliable strategies to evaluate the severity of smoke taint in smoke-affected wine in its early stage. This project uses acid hydrolysis to explore the relationship between the concentrations of smoke-derived volatile phenols and their glycosides in smoke-affected wines, as well as to evaluate the formation of artifacts, i.e., increases in volatile phenols originating from precursors other than phenolic glycosides. Wines made from fruit exposed to smoke were acidified to pH 1.0 and placed in an 80 C water bath for 0, 30, 60, 90, 120, 180, 240, 300, and 360 minutes time intervals. As the glycosidic bond between the volatile phenol and the sugar molecule is acid labile, these glycosidic bonds can be hydrolyzed by treatment of the sample with strong acids and heating. To quench the hydrolysis reaction, samples were adjusted back to pH 3.5 for chemical analysis. Compositional data obtained from GC-MS and Q-TOF LC-MS were used to explore the properties of glycosides in smoke-affected wines. Wines made from smoke-exposed grapes have significant acid hydrolysis rates and extents than wines made from non-smoke-exposed grapes in eleven volatile phenols during acid hydrolysis time trial. Additionally, the hydrolysis rate varied amongst the phenols measured, likely reflecting the types of precursor being hydrolyzed. Syringol, in particular, was associated with complex chemical kinetics in acid hydrolysis. By analyzing the phenolic concentration change of GC-MS data over time, the artifactual concentration can be determined from the intercept. Phenols like Syringol, with proportionally less artifact production, may be more valuable markers for measuring smoke exposure, although they may not necessarily indicate the perceived sensory level of smoke taint. Moreover, five glycosides were found as potential precursors for smoke-taint phenols using a workflow targeting smoke-derived glycosides from the QTOF LC-MS data. Overall, this study provides fundamental insight for more promising research avenues on assessing wine smoke taint risk using acid hydrolysis time trials with GC-MS analysis.
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Details
- Title
- Compositional Changes of Smoke-Derived Volatile Phenols and Their Glycoconjugates in Wine During Acid Hydrolysis
- Creators
- Yue Shang
- Contributors
- Tom TC Collins (Advisor)Stephen SF Ficklin (Committee Member)Michelle M Moyer (Committee Member)Bob BC Coleman (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Horticulture, Department of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University
- Number of pages
- 64
- Identifiers
- 99901019938201842
- Language
- English
- Resource Type
- Thesis