Characterization of odor-active compounds in Californian chardonnay wines using GC-olfactometry and GC-mass spectrometry.

Nineteen commercial Californian Chardonnay wines were analyzed by gas chromatography-mass spectrometry (GC-MS). Freon extracts of wines were separated by silica gel chromatography into three fractions. Volatiles were quantified by GC analysis of each fraction using internal standards added to the wine prior to Freon extraction. Twelve of the 19 wines were evaluated by GC-Olfactometry (GC-O). Of the 81 compounds shown to be odor-active (OA) by GC/O, 74 were quantified and 61 were tentatively identified, all of which had been previously reported in grapes or wines. Overall concentrations of compounds with floral or oak-related aromas were higher in wines shown by descriptive analysis to be high in intensity of either floral or oak notes, respectively. The relationship between sensory intensity ratings from a previous descriptive analysis of the wines and 74 OA compounds was modeled by partial least-squares regression (PLS) analysis. This PLS model only explained 17% of the variation in the OA variables, whereas a PLS using a subset of 16 OA peaks explained 64 and 47% of variance in the sensory and GC data, respectively. Fruity wines high in peach, citrus, and floral terms were separated from those high in oak-related sensory attributes (oak, vanilla, caramel, spice, and butter). In both PLS models, the fruity and floral terms were associated with isoamyl acetate, 2-phenylethyl acetate, linalool and two unknowns exhibiting minty and bandaid-caramel odors; the oaky attributes were associated with vanillin, oak-lactones, 4-ethyl guaiacol, gamma-nonalactone, 2-acetyl furan, eugenol, 2-methoxy phenol, and two unknowns with plastic and smoky odors.