Stabilization of jiuyaoquality for huangjiubrewing by fortifying functional strains based on core microbial community analysis

Jiuyaoas a generally small saccharifying and spontaneously fermenting starter is indispensable for huangjiubrewing. However, jiuyaocurrently in use is facing a major challenge of standardized manufacturing because of its open operating environment and rather primitive operations. This study provided a stead manufacturing procedure for jiuyaoby controlling the processing parameters. Saccharomycopsis fibuligeraand Rhizopus microsporuswere revealed as the core functional species related to starch-degrading enzyme activities with single-molecule real-time (SMRT) sequencing. Two strains with high starch-degrading abilities were successfully isolated and identified as Saccharomycopsis fibuligeraCY2111 and Rhizopus microsporusSM4. Meanwhile, the environmental fermentation parameters of jiuyaowere optimized to enhance enzyme activities. The glucoamylase and α-amylase activities of fortified jiuyaowith strain CY2111 and SM4 were 3.07 and 3.15 times that of traditional jiuyao, respectively. Moreover, the alcohol content increased by approximately 7.5% when fortified jiuyaowas used for huangjiubrewing. The flavor profiles determined by gas chromatography–mass spectrometry indicated there was no significant difference in the key aromas between the huangjiufermented with fortified jiuyaoand that of traditional jiuyao. Further, fortified jiuyaoproduced more pleasant esters in huangjiusuch as ethyl isovalerate, isoamyl acetate, and ethyl caprylate. Combined with the sensory evaluation, huangjiufermented with fortified jiuyaopresented stronger fruity aroma. These results demonstrated that careful fermentation settings combined with biofortification technology were feasible to improve jiuyaoquality, thus promoting huangjiuflavor. Taken together, it provided scientific guidance to improve traditional handcrafting and scale up the production of jiuyaounder controllable fermentation.