Optimization of preparation process of mixed-strain Fuqu and its application in light-flavor Baijiu production

In order to save the culture time and raw materials of single strain Fuqu, simplify the preparation process of Fuqu, and improve the production efficiency of Fuqu, a mixed-strain Fuqu was prepared using Saccharomycopsis fibuligera and Rhizopus spp. With saccharification power and viable yeast cell counts as evaluation indexes, the preparation process conditions were optimized through single-factor and orthogonal experiments. The mixed-strain Fuqu was applied to the brewing of light-flavor (Qingxiangxing) Baijiu. The physicochemical indexes and changes of volatile flavor substances during the fermentation process of light-flavor Baijiu were studied by conventional detection methods and headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS) method, and the effect of mixed-strain Fuqu addition on the flavor of light-flavor Baijiu was investigated. The results showed that the optimal preparation process conditions for the mixed-strain Fuqu were as follows: culture temperature 30 ℃, moisture 45%, and cultivation time 36 h. Under these optimal conditions, the saccharification power was 582 U/g, and the viable yeast cell counts were 8.42×10⁸ CFU/g. The mixed-strain Fuqu was applied to light-flavor Baijiu brewing, using commercial Fuqu as the control group, the mixed-strain Fuqu significantly increased the acidity of the fermented grains (P<0.05) and enhanced the contents of ethyl acetate and ethyl lactate, which were 1 798.43 mg/L and 666.91 mg/L, respectively. The results showed that the application of mixed-strain Fuqu in the light-flavor Baijiu brewing could increase the contents of main flavor substances and simplify the Fuqu-making process, providing a new idea for light-flavor Baijiu Jiuqu production.