State Key Laboratory of Food Science and Technology, Key Laboratory of Industrial Biotechnology of Ministry of Education, Synergetic Innovation Center of Food Safety and Nutrition, School of Biotechnology, Jiangnan University, Wuxi, Jiangsu 214122, China.
State Key Laboratory of Food Science and Technology, Key Laboratory of Industrial Biotechnology of Ministry of Education, Synergetic Innovation Center of Food Safety and Nutrition, School of Biotechnology, Jiangnan University, Wuxi, Jiangsu 214122, China.
Int J Food Microbiol. 2014 Jun 2;179:80-4. doi: 10.1016/j.ijfoodmicro.2014.03.011. Epub 2014 Mar 15.
Maotai-flavor liquor is produced by simultaneous saccharification and fermentation (SSF) process under solid state conditions, including Daqu (starter) making, stacking fermentation and alcohol fermentation stages. Filamentous fungi produce many enzymes to degrade the starch material into fermentable sugar during liquor fermentation. This study investigated the filamentous fungal community associated with liquor making process. Eight and seven different fungal species were identified by using culture-dependent and -independent method (PCR-denaturing gradient gel electrophoresis, DGGE) analyses, respectively. The traditional enumeration method showed that Daqu provided 7 fungal species for stacking fermentation. The total population of filamentous fungi increased from 3.4 × 10(3)cfu/g to 1.28 × 10(4)cfu/g in the first 3 days of stacking fermentation, and then decreased till the end. In alcohol fermentation in pits, the population continuously decreased and few fungal species survived (lower than 1 × 10(3)cfu/g) after 10 days. Therefore, stacking fermentation is an essential stage for the growth of filamentous fungi. Paecilomyces variotii, Aspergillus oryzae and Aspergillus terreus were detected by both methods, and P. variotii and A. oryzae were the predominant species. Meanwhile, P. variotii possessed the highest glucoamylase (3252 ± 526 U/g) and A. oryzae exhibited the highest α-amylase (1491 ± 324 U/g) activity among the cultivable fungal species. Furthermore, the variation of starch and reducing sugar content was consistent with the growth of P. variotii and A. oryzae in Zaopei (fermented grains) during stacking fermentation, which implied that the two filamentous fungi played an important role in producing amylase for hydrolyzing the starch.
茅台酒是采用固态法边糖化、边发酵酿制而成，包括制曲、堆积发酵和酒精发酵阶段。在白酒发酵过程中，丝状真菌产生许多酶，将淀粉物质降解为可发酵糖。本研究调查了与白酒酿造过程相关的丝状真菌群落。分别采用培养依赖和非依赖方法（PCR-变性梯度凝胶电泳，DGGE）分析，鉴定了 8 种和 7 种不同的真菌种类。传统的计数方法表明，大曲为堆积发酵提供了 7 种真菌。堆积发酵的前 3 天，丝状真菌的总种群从 3.4×10^3cfu/g 增加到 1.28×10^4cfu/g，然后下降直至结束。在窖内酒精发酵中，种群数量持续下降，10 天后只有少数真菌存活（低于 1×10^3cfu/g）。因此，堆积发酵是丝状真菌生长的重要阶段。交替单胞菌、米曲霉和土曲霉通过两种方法都有检测到，其中交替单胞菌和米曲霉是主要的种类。同时，交替单胞菌具有最高的糖化酶（3252±526 U/g），米曲霉具有最高的α-淀粉酶（1491±324 U/g）活性。此外，在堆积发酵过程中，糟醅中交替单胞菌和米曲霉的生长与淀粉和还原糖含量的变化一致，这表明这两种丝状真菌在产生淀粉酶以水解淀粉方面发挥了重要作用。
