功能微生物组对浓香型白酒上层酒醅发酵微生物群落及挥发性风味物质的影响

Effects of the functional microbiome on the microbial community and volatile flavor compounds of the upper-layer fermented grains of Nongxiangxing Baijiu

摘要:

【背景】 浓香型白酒上层酒醅发酵普遍存在原料利用率低、风味品质差等问题。【目的】 提升浓香型白酒上层酒醅出酒率和原酒品质。【方法】 采用功能微生物组(高产淀粉酶和酯类化合物)进行强化发酵。【结果】 功能微生物组强化使得上层酒醅中淀粉利用率提高了23.6%，原酒中乙醇含量提高了33.3%，酯类风味物质含量提高了31.4%；同时显著提升了酒醅中乳杆菌属(Lactobacillus)、毕赤酵母属(Pichia)和嗜热子囊菌属(Thermoascus)的相对丰度，降低了芽孢杆菌属(Bacillus)、克罗彭斯特菌属(Kroppenstedtia)和曲霉属(Aspergillus)的相对丰度，这些微生物属相对丰度的变化导致基酒中己酸、辛酸、己酸乙酯和乙酸乙酯等13种挥发性化合物含量存在显著差异。Spearman相关性分析表明，酒醅中水分、还原糖含量及酸度与主要微生物属具有显著的正相关性，是酒醅发酵过程中重要的驱动因子。分析预测了酒醅的不同发酵阶段微生物代谢途径中丰度差异显著的功能酶，表明酒醅微生物群落的变化是不同发酵时期代谢差异的主要原因。【结论】 系统探究了功能微生物组扰动对浓香型白酒上层酒醅发酵过程的理化特性、微生物群落演替及挥发性风味物质合成的影响作用，为通过功能微生物强化的方式优化浓香型白酒酿造工艺提供参考。

Abstract:

[Background] In the fermentation of the upper-layer fermented grains of Nongxiangxing Baijiu, there are widespread issues such as low raw material utilization rate and poor flavor quality. [Objective] To improve the yield and quality of Nongxiangxing Baijiu from the upper-layer fermented grains. [Methods] In this study, functional microbiomes (with high yields of amylase and ester compounds) were used for enhanced fermentation. [Results] The results showed that the enhancement with the functional microbiome increased the starch utilization rate in the upper-layer fermented grains by 23.6%, the content of ethanol in the crude Baijiu by 33.3%, and the content of ester flavor substances by 31.4%. At the same time, the functional microbiome significantly increased the relative abundance of Lactobacillus, Limosilactobacillus, Pichia, and Thermoascus while decreasing the relative abundance of Bacillus, Kroppenstedtia, and Aspergillus in the fermented grains. The changes in the relative abundance of these microbial genera led to significant differences in the content of 13 volatile compounds such as caproic acid, caprylic acid, ethyl caproate, and ethyl acetate in crude Baijiu. Spearman correlation analysis indicated that moisture, reducing sugar content, and acidity had significant positive correlations with the main microbial genera and were important driving factors in the fermentation process of fermented grains. Analysis indicated that the functional enzymes and their abundance of the microbial community in the fermented grains showed significant differences at different fermentation stages. It suggested that the microbial community changes in the fermented grains were the main cause of metabolic differences at different fermentation stages. [Conclusion] This study systematically investigated the effects of functional microbiome disturbance on the physical and chemical properties of the upper-layer fermented grains of Nongxiangxing Baijiu, the succession of the microbial community, and the synthesis of volatile flavor substances during the fermentation process, providing a reference for optimizing the brewing process of Nongxiangxing Baijiu through enhancement with functional microbiomes.