Activities analysis of main functional enzymes from strong-flavour Daqu of Chinese liquor during fermentation and storage stages

In order to deeply research the functional enzymes in strong-falvour Daqu of Chinese liquor, based on the process of production, fermentation and maturation of Daqu, the activities and variation of α-amylase, tannase, xylanase and lipase from samples derived from Daqu chunks' skin and core, were investigated at 10 processing points. The results exhibited that the activities of α-amylase from Qupi fluctuated between 523.28~765.78 U during Daqu fermentation phase. However, after rapid rise and fall at the fermentation stage, the Quxin α-amylase activities maintained about 350 U at the later stage of maturation. There were similar variations of tannase activities between Qupi and Quxin samples with early rapidly increasing up to the highest activities at Houhuo and slowly decreasing later. Both the xylanase activities from Qupi and Quxin samples all increased during the period of Shaping to Yangqu, the highest activities were 119.72 U and 113.70 U, respectively. Then, they decreased at the later maturation phase. Compared with other enzymes, the change trends of lipase activities between Qupi and Quxin were far different from each other. For Qupi samples, lipase activities first increased and then decreased, then increased and decreased later. However, the lipase activities from Quxin samples rapidly decreased after gradually increased to the highest value (597.50 U) at the stage of one-month maturation. After that, a slight increasing of activities was observed. The study on variation of the main enzymatic activities during fermentation and maturation from Daqu of Chinese liquor, would be a kind of guidance for isolation and screening of some special enzyme producers and useful basis for the improvement of Daqu making-process and research of strengthen Daqu.