Solid state fermentation characteristics of Geotrichum sp. in strong-flavor Baijiu
YOU Ling1,2, TAN Yi1, LONG Qingyang1, CHEN Hong1, ZHOU Rongqing2*, ZHAO Dong1*
1(Key Laboratory of Sichuan Province for the Utilization of Solid State Fermentation Resources, Yibin University, Yibin 644000, China) 2(College of Biomass Science and Engineering, Sichuan University, Chengdu 610065, China)
Abstract: In order to explore the roles of Geotrichum sp. in the strong-flavor Baijiu fermentation, two strains were isolated from the fermented grains of strong-flavor Baijiu. Their growth and metabolism characteristics were studied. It was found that the similarity of 26S rDNA sequence between the two isolated strains and four strains of Geotrichum was higher than 99%, and the utilization of sugars were also similar to Geotrichum sp., while could not form pseudohyphae. The two strains could tolerate pH 4.0 and 6% vol ethanol, and the optimum growth temperature was 28 ℃ in L-YPD medium. In the fermented grains, the two isolated strains started the slow but constantly fermentation ethanol production was 7.91 and 6.71 mL/100 g, respectively, which was 2.5 and 4.5 times of liquid fermentation, while the total yield of flavor substances was 91 and 340 times of liquid fermentation, respectively. They produced 1.5 and 3.0 g/kg ethyl acetate, 216 and 573 mg/kg isoamyl acetate, 658 and 477 mg/kg β-phenylethanol in grains. The Geotrichum sp. grew well in the fermented grains of strong-flavor Baijiu, with constant fermentation and produced more ethanol than that of commercial yeast, and could improve the flower and fruit aroma of strong-flavor Baijiu, thus showed application prospect of new commercial yeast for Baijiu.
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