Analysis, occurrence, and potential sensory significance of tropical fruit aroma thiols, 3-mercaptohexanol and 4-methyl-4-mercapto-2-pentanone, in Chinese Baijiu

Fruity notes are important to the flavor of Baijiu (Chinese Liquor) and are considered to originate from ester compounds; however, little is known about the other chemicals that contribute to the fruity aroma. In this study, the sensory impacts of two tropical fruit aroma thiols, 3-mercaptohexanol (3MH) and 4-methyl-4-mercapto-2pentanone (4MP), in Chinese Light-, Strong- and Soy sauce flavor type Baijiu were systemically subjected to a sensory evaluation, qualitative and quantitative analysis, and multivariate statistical analyses. The flavor dilution factors of 3MH and 4MP were 9-729. The contents of 3MH and 4MP were the highest (p < 0.001) in Strong- and Soy sauce aroma-type Baijiu, respectively. According to their odor activity values (OAVs), 3MH (OAV: 1-22) and 4MP (OAV: 1-9) are important to the aroma of Baijiu. Notably, 4MP was identified for the first time in Baijiu, and the multivariate statistical analysis demonstrated that 3MH and 4MP could be used to differentiate Baijiu.