Characterization of volatile bitter off-taste compounds in Maotai-flavor baijiu (Chinese liquor)

Bitterness in baijiu (Chinese liquor) gives consumers an unpleasant feeling, directly affecting the quality and grade of baijiu. Using semipreparative reversed-phase high-performance liquid chromatography (RP–HPLC) and gas chromatography-mass spectrometry (GC–MS) techniques, the sensory analysis approach was applied to analyze the volatile bitter compounds in Maotai-flavor baijiu through activity-guided fractionation combined with taste dilution analysis (TDA). It was found that 1-propanol, 1-butanol, 2-methylpropanol, 3-methylbutanol, 2-phenylethanol, furfural, 5-methyl-2-furfural, and ethyl lactate were the volatile bitter compounds in Maotai-flavor baijiu. Among them, 2-phenylethanol, 5-methyl-2-furfural, and ethyl lactate were reported for the first time as bitter compounds in baijiu. The recombination experiment confirmed that combining these eight volatile bitter compounds reproduced baijiu bitterness, and the omission experiment identified furfural, 1-propanol, 3-methylbutanol, 2-methylpropanol, and ethyl lactate as the main contributors to baijiu bitterness. These findings emphasized that volatile compounds are the main contributors to baijiu bitterness. It provided crucial guidance for identifying taste compounds in baijiu and mitigating its bitterness. • The volatile bitter compounds are extracted, separated, and identified from baijiu. • Three compounds are reported as bitter compounds in baijiu for the first time. • The recombination of eight volatile bitter compounds reproduces baijiu bitterness. • The key contributors to baijiu bitterness are identified by omission experiment. • Baijiu bitterness is mainly contributed by volatile compounds.