Discrimination of Smoke-Exposed Pinot Noir Wines by Volatile Phenols and Volatile Phenol-Glycosides

The study investigated the correlation of five primary volatile phenols (VPs) and their glycosides in smoke-exposed and non-smoke-exposed Pinot noir wines to evaluate and identify the potential markers for smoke taint. The results showed that all putative VP-glycosides in smoke-exposed wines were higher than in non-smoke-exposed wines, with a fold change ranging from 2.1 to 31.9 for the top fifteen differentiations. VP-glycosides showed strong positive correlations among themselves, with the correlation coefficients for hexose-guaiacol vs. pentose (P)-hexose (H)-cresol and syringyl-β-D-glucopyranoside vs. H-P-4-methylguaiacol of 0.94 and 0.92. VP-glycosides also showed relatively high correlations with free and strong acid-hydrolyzed VPs. For example, H-P-guaiacol vs. free-form guaiacol, and H-P-guaiacol vs. total guaiacol the 0.71, and 0.78. The strong correlation indicates that these compounds are connected and regulated by the severity of the smoke exposure. Multivariate analysis effectively differentiated smoke-exposed wines from non-smoke-exposed ones. However, more research is needed to fill the gaps in understanding smoke-derived compounds.