红酸汤发酵过程中微生物区系及挥发性物质组成变化分析

本研究以红酸汤的调配原料辣椒和西红柿酸汤为研究对象，采用Illumina MiSeq测序、总酸滴定、气相色谱-质谱联用等设备或方法，对两种酸汤发酵过程中的微生物区系、总酸、pH和挥发性物质的变化趋势予以分析。结果表明，纳木雷氏乳杆菌（27.67%）和戊糖乳杆菌（41.75%）分别为辣椒酸汤和西红柿酸汤的优势乳酸菌；汉逊德巴利酵母（76.05%）和膜璞毕赤酵母（80.88%）则分别为两种酸汤发酵后期的优势真菌。发酵过程中，辣椒和西红柿酸汤的pH和总酸含量于21~28 d之间达到或接近极值，分别为3.57、3.25和42.87 g/kg、47.52 g/kg。挥发性物质方面，辣椒酸汤和西红柿酸汤中分别检测到醇、酮、醛、酯等各类化合物156和92种。其中，酯类（24.99%）、萜烯类（20.21%）和酮类（17.60%）是辣椒酸汤在发酵早期（1 d）含量较高的几类化合物；西红柿酸汤中则以醛类（41.30%）和酮类（20.28%）化合物为主。随着发酵期变化，辣椒酸汤的主要风味物质为醇类、酯类化合物，以芳樟醇（10.43%）、十六酸乙酯（12.12%）等为代表；西红柿酸汤中则以醇类和酚类为优势，其中，苯乙醇（31.93%）、4-乙基苯酚（8.71%）为西红柿酸汤风味贡献了重要作用。综上所述，自然发酵酸汤中的优势功能微生物为乳酸菌和酵母菌，且可发酵后21~28 d内得到高于25 g/kg的总酸含量，符合红酸汤产品的质量要求，挥发性物质随发酵期变化差异较大，相关数据可为酸汤直投式发酵剂研制及加工工艺优化提供参考。

Analysis of Microflora and Volatile Substances Change in Red Sour Soup during Fermentation

In this study, pepper and tomato sour soup, the raw materials of red sour soup were taken as the research objects. Illumina MiSeq, total acid titration, gas chromatography-mass spectrometry and other equipment or methods are used to analyze the dynamic trend of microflora, total acid, pH value and volatile substances in the fermentation process of two kinds of sour soup. The results showed that Lactobacillus namurensis (27.67%) and Lactobacillus pentosus (41.75%) were the dominant lactic acid bacteria in pepper and tomato sour soup, respectively; Debaryomyces hansenii (76.05%, pepper sour soup) and Pichia membranifaciens (80.88%, tomato sour soup) were the dominant fungi in the later stage of fermentation. In terms of volatile substances, 156 and 92 compounds such as alcohols, ketones, aldehydes and esters were detected in pepper and tomato sour soup respectively. Among them, esters (24.99%), terpenes (20.21%) and ketones (17.60%) were several compounds with high content in chili acid soup in the early stage of fermentation; In tomato sour soup, aldehydes (41.30%) and ketones (20.28%) were the main compounds. With the change of fermentation, the main flavor compounds of chili acid soup were alcohols and esters, represented by linalool (10.43%) and ethyl hexadecanoate (12.12%); In tomato sour soup, alcohols, esters and phenols were the advantages. Among them, phenylethanol (31.93%) and 4-ethylphenol (8.71%) played an important role in the flavor of tomato sour soup. In general, the dominant functional microorganisms in the naturally fermented sour soup are Lactobacillus and yeast, and the total acid content higher than 25 g/kg can be obtained within 21~28 days after fermentation. The volatile substances vary greatly with the fermentation period. The relevant data can provide a reference for the development of directed vat set for sour soup and the optimization of processing technology.