为解析浓香型白酒发酵周期与原酒品质的关系,跟踪了发酵周期长达5个月的窖池,并重点关注了窖池下层酒醅中主要风味物质和微生物菌群的动态变化。研究发现酒醅中的乳酸、乙酸在发酵初期(0~14 d)迅速增加,之后增速放缓;己酸、丁酸以及己酸乙酯含量则随发酵时间的延长逐渐增加。整个发酵过程中,乳杆菌科占绝对优势,随着发酵时间的延长,酒醅中瘤胃菌科(Ruminococcaceae)和梭菌科(Clostridiaceae_1)微生物的相对丰度逐渐上升,这些微生物也是窖泥中的高丰度微生物。结果表明,在长期发酵过程中,窖泥为酒醅持续不断地提供其主体的厌氧微生物。相关性分析进一步表明,这些微生物对发酵后期己酸、丁酸、乙酸的合成具有重要贡献。虽然窖泥来源的微生物在酒醅微生物中占比较低,但对于浓香型白酒的贡献却非常巨大。该研究为从发酵角度控制浓香型原酒品质提供了重要参考。
This study revealed the correlation between the fermentation period and the quality of Chinese strong aroma-type Baijiu during five-month fermentation. The key flavor compounds and microbial community in fermented grains at the bottom layer were analyzed. It was found that lactic acid and acetic acid increased rapidly within 14 d of fermentation and followed by a moderate increase. Caproic acid, butyric acid and ethyl caproate gradually increased during fermentation. Lactobacillaceae sp. was dominant throughout the whole fermentation process, and the relative abundances of Ruminococcaceae sp. and Clostridiaceae_1 sp., two families with high abundances in pit muds, gradually increased. These results indicated that pit muds continuously provided anaerobic microorganisms for fermented grains during long-term fermentation, and these microorganisms played key roles in production of caproic acid, butyric acid and acetic acid. Although the abundances of anaerobic microorganisms originated from pit mud were low in fermented grains, they essentially contributed the flavor of strong aroma-type Baijiu, which provides a vital reference to control the quality of raw strong aroma-type Baijiu.
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