Soaking induced discrepancies in oenological properties, flavor profiles, microbial community and sensory characteristic of Huangjiu (Chinese rice wine)

Soaking is a crucial process in adjusting initial fermentation acidity and achieving desired flavor quality of rice wines. Effects of soaking time on physicochemical characteristic of rice, flavor profiles, microbial community and sensory characteristic of Huangjiu were investigated. Soaking caused significantly changes in amylopectin content, and rice with high amylopectin content was conducive to produce esters and aldehydes during Hungjiu brewing. High-throughput sequencing showed that bacteria types were more abundant than fungi during brewing, suggesting that bacterial community might be primarily responsible for Huangjiu flavor. Differential analysis revealed that Weissella and Enterobacter contributed greatly to the accumulation of alcohols, esters and aldehydes during Huangjiu brewing, while Clostridium, Acinetobacter, Cyanobacteria, Zymomonas and Exiguo-bacterium were responsible for the rancidity. Based on spearman's correlation analysis, Lactococcus, Weissella, Pediococcus, Lactobacillus and Staphylococcus were the key microbial genera responsible for the flavor characteristic of Huangjiu. While favorable soaking caused an increased intensity in alcohol-aroma, full body and continuation of resultant Huangjiu, insufficient soaking led to a higher intensity of bitter taste. Summarily, soaking acidity ranged from 2 to 3 g/L was beneficial for preventing rancidity and improving the production of flavor compounds in Huangjiu.