Studies on Key Aroma-Active Compounds in Three Traditional Douchi by Sensory-Directed Flavour Analysis

As a traditional fermented soybean product in China, douchi is rich in diversity and varies from place to place. Because of the significance in food culture, the douchi from Sichuan, Hunan, and Guizhou are quite typical and distinctive. By analysing the volatile components of these three types of douchi, we can not only deconstruct the cause of aroma formation, but also lay the foundation for flavour adjustment. In this study, the key aroma-active compounds of the three types of douchi were identified by gas chromatography–olfactometry (GC–O) and gas chromatography–mass spectrometry (GC–MS) combined with sensory evaluation. 32 aroma compounds were identified in Tongchuan douchi (TC), and 16 of them with flavour dilution (FD) > 4 were determined. 14 substances were quantified, and 4 of them with OAV > 1. 30 aroma compounds were identified in TongRen douchi (TR), and 15 of them with flavour FD ≥ 4 were determined. 13 substances were quantified, and 11 of them with OAV > 1. 21 aroma compounds were identified in LiuYang douchi (LY), and 11 of them with FD ≥ 4 were determined, and all of them were quantified. 5 substances with OAV > 1 were determined. The sensory evaluation determined that the three types of douchi possessed sauce-like, sour, burnt, bean aroma, roasted, salty, fermented aroma, and rancid aroma.