米酒主要是在Qu的帮助下通过糖化和液化由谷物制成。Qu在黄酒风味品质的形成中起着重要作用。红曲和小曲代表了两种流行的曲品种,它们通常用于米酒的酿造过程,并在其生产中起着至关重要的作用。在这项研究中,GC,GC-MS,HPLC,和宏基因组测序技术被用来对比微生物菌群,生物胺,以及米酒发酵过程中产生的香气特征,红曲和小曲被用作酿造过程的引发剂。结果表明,高级醇(包括正丙醇,异丁醇,3-甲基-1-丁醇,小曲(XQW)酿造的米酒和苯乙醇)明显高于红曲(HQW)酿造的米酒。相反,HQW中的生物胺浓度明显超过XQW,但酪胺在XQW中显著富集,在HQW中未检测到。此外,多元统计分析显示,HQW和XQW之间的挥发性成分组成存在明显差异。己酸,乙酸乙酯,乙酸异戊酯,己酸乙酯,癸酸乙酯,2-甲氧基-4-乙烯基苯酚,等。,被鉴定为HQW和XQW中的特征性香气活性化合物。基于宏基因组测序的微生物组分析表明,HQW和XQW在酿造过程中具有不同的优势微生物。伯克霍尔德利亚,克雷伯菌属,明串珠菌,红曲霉,和曲霉被鉴定为HQW发酵期的主要微生物属,而片球菌,肠杆菌,根霉,Ascoidea,Wickerhamomyces是XQW酿造过程中的主要微生物属。生物信息学分析表明,参与生物胺和酯生物合成的微生物基因在HQW中的浓度明显高于XQW中的浓度。而与糖酵解相关的基因的含量,高级醇生物合成,XQW的脂肪酸代谢明显高于HQW,从微生物功能基因的角度分析两种黄酒风味品质差异的可能原因。
Rice wine is primarily crafted from grains through saccharification and liquification with the help of Qu. Qu plays an important role in the formation of the flavor quality of rice wine. Hongqu and Xiaoqu represent two prevalent varieties of Qu that are typically utilized in the brewing process of rice wine and play a crucial role in its production. In this study, GC, GC-MS, HPLC, and metagenomic sequencing techniques were used to contrast the microbial flora, biogenic amines, and aroma characteristics developed during the fermentation of rice wines, with Hongqu and Xiaoqu being used as initiating agents for the brewing process. The results show that the content of higher alcohols (including n-propanol, isobutanol, 3-methyl-1-butanol, and phenethyl alcohol) in rice wine brewed with Xiaoqu (XQW) was significantly higher than that in rice wine brewed with Hongqu (HQW). Contrarily, the concentration of biogenic amines in HQW surpassed that of XQW by a notable margin, but tyramine was significantly enriched in XQW and not detected in HQW. In addition, a multivariate statistical analysis revealed distinct disparities in the constitution of volatile components between HQW and XQW. Hexanoic acid, ethyl acetate, isoamyl acetate, ethyl caproate, ethyl decanoate, 2-methoxy-4-vinylphenol, etc., were identified as the characteristic aroma-active compounds in HQW and XQW. A microbiome analysis based on metagenomic sequencing showed that HQW and XQW had different dominant microorganisms in the brewing process. Burkholderia, Klebsiella, Leuconostoc, Monascus, and Aspergillus were identified as the primary microbial genera in the HQW fermentation period, while Pediococcus, Enterobacter, Rhizopus, Ascoidea, and Wickerhamomyces were the main microbial genera in the XQW brewing process. A bioinformatics analysis revealed that the concentrations of microbial genes involved in biogenic amines and esters biosynthesis were significantly higher in HQW than those in XQW, while the content of genes relevant to glycolysis, higher alcohol biosynthesis, and fatty acid metabolism was significantly higher in XQW than in HQW, which are the possible reasons for the difference in flavor quality between the two kinds of rice wine from the perspective of microbial functional genes.