Characterisation of physicochemical properties, flavour components and microbial community in Chinese Guojing roasted sesame‐like flavour Daqu

Daqu is a saccharifying and fermentation agent for Baijiu production. It provides ingredients, flavours or flavour precursors, microorganisms and enzymes that influence Baijiu quality and character. Here, a systematic investigation was performed on the physicochemical properties, volatile flavour compounds and microbial community structures of Chinese Guojing roasted sesame‐like flavour Daqu . The results show that the Daqu exhibited high saccharifying ability, but low liquefying and fermenting ability. Analysis by headspace solid‐phase microextraction gas chromatography–mass spectrometry showed that the Daqu and a simulated solid‐state fermentation sample contained 28 and 49 volatile components, including alcohols, esters, aldehydes, benzodiazepines, alkenes and nitrogen containing compounds. The main volatiles were aldehydes, esters and alcohols in Daqu , while the esters, alcohols and phenols were relatively higher in the solid‐state fermentation sample. With the microbial flora, Bacillus , Actinobacteria _norank, Thermoactinomyces , Enterobacteriaceae _norank, Enterobacter , Actinopolyspora , Kroppenstedtia , Pseudomonas and Sphingobium were the main prokaryotic microorganisms. The dominant fungi were Thermomucor , Trichocomaceae _Incertae Sedis, Absidia , Eurotiomycetes _Incertae Sedis, Mucorales _Incertae Sedis and Eurotiales _Incertae Sedis. By systematically characterising the physicochemical properties, flavour compounds and microorganisms in Daqu , this study increases the understanding of Daqu and provides information for improvements in Baijiu production and quality. © 2019 The Institute of Brewing & Distilling