Comparing the differences of characteristic flavour between natural maturation and starter culture for Mucor-type Douchi

In this research, effects of maturation times on volatiles of Mucor-type Douchi were investigated. Results showed that 2-year matured sample exhibited higher concentrations of characteristic flavours including alcohols, esters, phenols, ketones and pyrazines. Additionally, effects of starter cultures addition on volatiles were investigated, and results demonstrated that inoculated fermented samples presented higher amounts of aldehydes, ketones, phenols and pyrazines compared with that of naturally fermented sample. Analysis of odour activity value (OAV) suggested that increased OAVs of eight compounds that mainly contributed to the flavour of Douchi ranged from onefold to 6.5-fold in the Tetragenococcus halophilus, Zygosaccharomyces rouxii and Candida versatilis co-cultured sample. Furtherly, by comparing the characteristic flavour of co-cultured and 2-year matured samples, no significant difference was observed in the OAV of flavour except rose-like and soapy flavour, which indicated that co-culture of the three strains during Douchi fermentation may facilitate the formation of flavours and shorten the fermentation process.