Characterization of aroma-active compounds changes of Xiecun Huangjius with different aging years based on odor activity values and multivariate analysis.

Aging is an indispensable process to endow Huangjiu with harmonious and pleasant fragrances. To elucidate the effects of aging time on aroma characteristics of Xiecun Huangjius, 5 samples aged for different years (3 to 9 years) were investigated by sensory evaluation, gas chromatography-mass spectrometry-olfactometry/detection frequency (GC-MS-O/DF), and odor activity values (OAV) analysis. Sensory results showed significant differences existed among different aged Xiecun Huangjius. Totally, 54 compounds in Xiecun Huangjius were identified by GC-MS and further quantified. Of these, 16 were confirmed as key aroma-active compounds with high OAVs and DFs. Partial least squares regression (PLSR) indicated that the old-aged Y9 sample was greatly related to most aroma-active compounds, thus presented the coordinated overall flavor. Together with orthogonal partial least squares-discriminant analysis (OPLS-DA), 4 compounds (diethyl succinate, furfural, nonanal and isoamyl alcohol) were determined as the main markers for classification of the old-aged Y9 and the other-aged samples.