酱香型白酒发酵中酵母群落结构及其对风味组分的影响

Yeast community structure and its impact on flavor components during the fermentation process of Chinese Maotai-flavor liquor

摘要:

【目的】研究酱香型白酒发酵过程中酵母群落结构，及其对酱香型白酒生产的影响。【方法】通过变性梯度凝胶电泳(DGGE)和实时荧光定量PCR (RT-qPCR)技术分别对产量、酒质较高的第五轮次和较低的第七轮次发酵过程中的酵母群落结构进行解析，同时利用顶空固相微萃取气质联用(HS-SPME-GC-MS)以及高效液相色谱(HPLC)技术分析酒醅中的代谢组分，初步分析了酵母群落对酱香型白酒产量及品质的影响。【结果】用DGGE方法从酒醅中的检测到Issatchenkia orientalis、Torulaspora delbrueckii、Pichia galeiformis、Schizosaccharomyces pombe、Galactomyces geotrichum、Trichosporon asahii、Zygosaccharomyces bailii、Saccharomyces cerevisiae和Pichia fabianii等9种含量丰富的酵母，其中G. geotrichum和S. cerevisiae是第五轮的优势酵母，而第七轮的优势酵母增加了I. orientalis和Z. bailii两种酵母，且Sc. pombe未检测到。第七轮发酵过程中5种酵母在发酵后期衰亡明显，第五轮酵母群落结构相对更稳定；发酵前期第五轮酵母总量是第七轮的2–5倍，而发酵结束时第五轮乙醇含量达到第七轮次的2.45倍。酒醅中挥发性风味组分种类丰富，第五轮中酯类等白酒中重要的风味物质含量明显高于第七轮，有机酸和杂醇油含量低于第七轮。【结论】酱香型白酒酿造过程中酵母菌群多样性较丰富，酵母菌群结构变化对白酒产量及品质影响明显，这为酱香型白酒酿造机制研究奠定了基础。

Abstract:

[Objective] To analyze yeast community structure and its influence on brewing during the fermentation process of Chinese Maotai-flavour liquor. [Methods] The yeast community in the fifth round (higher yield and quality of the liquor) and the seventh round of fermentation process (lower yield and quality of the liquor) were analyzed using denaturing gradient gel electrophoresis (DGGE) and real-time quantitative PCR (RT-qPCR). The metabolic components in the fermented grains were investigated through headspace-solid phase microextraction gas chromatograph-mass apectrometer (HS-SPME-GC-MS) and high performance liquid chromatography (HPLC). Finally, the effects of yeast communities on the yield and quality of Maotai-flavor liquor were analyzed. [Results] At least nine yeasts were detected in the fermented grains, including Issatchenkia orientalis, Torulaspora delbrueckii, Pichia galeiformis, Schizosaccharomyces pombe, Galactomyces geotrichum, Trichosporon asahii, Zygosaccharomyces bailii, Saccharomyces cerevisiae and Pichia fabianii. Among them, G. geotrichum and S. cerevisiae was dominant yeasts of the fifth round, while the other two yeast, I. orientalis and Z. bailii, were also advantage in seventh round and Sc. pombe was not detected. In addition, five kinds of yeasts declined significantly during latter period of the seventh round fermentation process, but the yeast community structure during the fifth round was relatively more stable. The total yeasts during the early stage of the fifth round fermentation is 2?5 times more than the seventh round’s, while ethanol content of fifth round fermented grains was 2.45 times as higher as the seventh’s at the end of fermentation. Besides, volatile metabolic component of fermented grains was rich in species. The content of esters of the fifth round was remarkably higher than the seventh round, while organic acids and fusel oils were lower than the seventh round. [Conclusion] During Maotai-flvour liquor brewing process, there is rich diversity in yeast species, and the dynamics of yeast community structure affect liquor’s yield and quality obviously, which provides the basis for the study of Maotai-flavour liquor brewing mechanism.