Analysis of off-flavor-bran flavor substances in strong-flavor Baijiu

In order to analyze the off-flavor-bran flavor substances in strong-flavor (Nongxiangxing) Baijiu, the sensory evaluation of normal and bran flavor raw liquor was conducted according to the relevant national standards, and the volatile flavor substances in normal and bran flavor raw liquor were detected by gas chromatography-mass spectrometry (GC-MS) and gas chromatography-olfactory-mass spectrometry (GC-O-MS) technology, and using partial least square-discriminant analysis (PLS-DA) to establish model. Important aroma compounds and important potential markers for the difference between normal and bran flavor raw liquor were screened using odor activity value (OAV) and variable importance in the projection (VIP) values, and the bran flavor substances were identified by aroma addition and omission tests. The results showed that the aroma of bran flavor in bran raw liquor were stronger compared with normal raw liquor, but the pit aroma, grains aroma, aging aroma and sour aroma were weaker. A total of 135 volatile flavor substances were detected in normal and bran raw liquor, including 64 important aroma compounds (OAV>1), and 32 important potential markers (VIP>1) causing the difference between normal and bran flavor of strong-flavor Baijiu were screened out by PLS-DA. The results of aroma addition and omission tests showed that the main cause of bran flavor of strong-flavor Baijiu was the interaction of soil flavin, diethyl succinate and ethyl benzoate.