RT Journal Article
SR Electronic
T1 Exploring Variation in Grape and Wine Volatile Phenol Glycoconjugates to Improve Evaluation of Smoke Taint Risk
JF American Journal of Enology and Viticulture
JO Am J Enol Vitic.
FD American Society for Enology and Viticulture
SP 0750013
DO 10.5344/ajev.2024.23060
VO 75
IS 1
A1 Szeto, Colleen
A1 Feng, Hui
A1 Sui, Qiang
A1 Blair, Bryant
A1 Mayfield, Sarah
A1 Pan, Bruce
A1 Wilkinson, Kerry
YR 2024
UL http://www.ajevonline.org/content/75/1/0750013.abstract
AB Background and goals When vineyards are exposed to wildfire smoke, resulting wines may exhibit unpleasant smoky, ashy attributes (i.e., smoke taint). Smoke exposure leads to elevated levels of volatile phenols and their glycoconjugates in grapes. However, predicting the risk of smoke taint in wine is challenging because some of these markers occur naturally, and few studies outside of Australia have investigated their varietal and/or regional variation. The goal of this study was therefore to explore variation in volatile phenol glycoconjugates (VPG) in California grapes and wine.Methods and key findings A method for measuring VPGs using Orbitrap mass spectrometry was developed and used to identify the VPGs most indicative of smoke exposure in grapes and wine in CA. Guaiacol, 4-methylguaiacol, cresol and phenol rutinosides, syringol and 4-methylsyringol gentiobiosides, cresol pentose glucoside, and phenol glucoside were consistently found at elevated concentrations (>20 µg/L) in smoke-affected wine. These concentrations were several-fold higher than those of wines from vintages minimally affected by smoke. Satellite imaging data were used to compare the location and density of smoke plumes during the 2018 and 2020 wildfire seasons. Measurement of the above subset of VPGs in grapes sampled during 2018 and 2020 showed they were positively correlated with total glycoconjugates (i.e., the sum of cresol rutinoside, guaiacol rutinoside, 4-methylguaiacol rutinoside, phenol rutinoside, syringol gentiobioside, and 4-methylsyringol gentiobioside concentrations), despite varied levels of total glycoconjugates.Conclusions and significance These research findings highlight the need for baseline data across different varieties and regions to enable more reliable screening of grapes potentially affected by smoke, and for sampling protocols that account for temporal and spatial variation in smoke exposure.