Changes in Smoke-Taint Volatile-Phenol Glycosides in Wildfire Smoke-Exposed Cabernet Sauvignon Grapes throughout Winemaking

Relative abundance of volatile-phenol glycosides in smoke-exposed grapes and during fermentation. (A) monosaccharide glycosides, (B) disaccharide glycosides, and (C) trisaccharide glycosides. Abundances reported are based on normalization to the internal standard salicin. The following five fermentation time points are shown: the juice at crush, the start of primary fermentation (25.0 Brix), the middle of primary fermentation (12.5 ± 1.0 Brix), the end of primary fermentation (<0 Brix), and wine at the bottling stage post-malolactic fermentation and filtering. Error bars represent standard deviation for nine replicate analyses (3 fermentation replications × 3 analytical replications). Bars with the same superscript are not statistically different at p < 0.05. An (*) by the compound name denotes that the normalized peak area was divided by 10. A signal-to-noise (S/N) of 10 was used for the limit of quantitation. The hexose guaiacol peak (A) had an S/N ratio of 3 to 5 depending on the sample; we have included relative concentrations for this peak to provide insight on the overall extent of hydrolysis.