Characterization of key aroma compounds in Rice flavor baijiu from different rice raw materials by gas chromatography-ion mobility spectrometry and gas chromatography-olfactometry-quadrupole time of flight mass spectrometry

Rice flavor baijiu is one of the four traditional Chinese liquors, but the flavor difference caused by rice raw materials has received little attention. In this study, gas chromatography-ion mobility spectrometry (GC-IMS) combined with gas chromatography-olfactometry-quadrupole time of flight mass spectrometry (GC-O-QTOF/MS) were used to analyze five Rice flavor baijiu brewed from different rice raw materials. The results showed that there was a significant difference in the number and content of aroma compounds between the baijiu made from japonica rice and indica rice, and a total of 34 volatiles were characterized by the GC-IMS technique, which effectively constructed the fingerprint profile of the flavor differences of Rice flavor baijiu. GC-O-QTOF combined with aromatic extract dilution analysis (AEDA) tests identified 42 characteristic aroma active regions, 34 of which could be identified and quantified by the internal standard method. Sixteen aroma-active compounds in five baijiu samples showed high odor activity values (OAV). In addition, multivariate statistical analyses such as principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) effectively revealed the distribution patterns of the samples and their separation of relevant aroma activity markers. Six key aroma compounds, including isopentyl acetate, ethyl hexanoate, benzeneacetaldehyde, phenethyl acetate, undecane-2-one, and ethyl decanoate, were screened to have a greater effect on the flavor of Rice flavor baijiu.