微生物代谢对美玉独特风味的形成具有重要意义,一种中国传统的发酵鱼片。然而,发酵过程中微生物与风味成分的相互作用关系尚不清楚。在这项研究中,采用电子鼻和顶空-固相微萃取-气相色谱-质谱联用技术对美玉发酵过程中的风味成分进行了鉴定,并进行了绝对微生物定量,以鉴定微生物群落的多样性和演替。在发酵过程中,挥发性化合物的种类有所增加。醇,醛类,芳香族化合物和酯类是主要的风味化合物,在美玉中显著增加,而碳氢化合物和醛类明显减少。乳酸菌的绝对丰度,发酵3天后,乳球菌和Weissella显著增加,与1-壬醇的产生密切相关,2-甲氧基-4-乙烯基苯酚,愈创木酚,棕榈酸乙酯和辛酸乙酯可能与脂肪酸生物合成和氨基酸代谢有关。然而,这些属与吲哚的产生呈负相关。此外,3天内发酵的美玉的总挥发性碱性氮(TVB-N)水平在25mgTVB-N/100g鱼的范围内,游离氨基酸含量和脂氧合酶活性明显低于发酵4天。鉴于食品安全和风味,建议在室温下自然发酵的美玉应控制在3天内。这项研究强调了绝对定量在传统发酵美玉微生物组分析中的应用,并为微生物在发酵过程中风味形成中的作用提供了新的见解。
Microbial metabolism is important for the unique flavor formation of Mei yu, a kind of traditional Chinese fermented fish pieces. However, the interactive relationship between microorganisms and flavor components during fermentation is still unclear. In this study, electronic nose and headspace-solid-phase microextraction-gas chromatography-mass spectrometry analysis were performed to identify flavor components in Mei yu during the fermentation, and the absolute microbial quantification was conducted to identify the diversity and succession of microbial communities. During fermentation, there was an increase in the types of volatile compounds. Alcohols, aldehydes, aromatics and esters were the main flavor compounds and significantly increased in Mei yu, while hydrocarbon and aldehydes significantly decreased. The absolute abundances of Lactobacillus, Lactococcus and Weissella increased significantly after 3 days\' fermentation, which were closely associated with the productions of 1-nonanol, 2-methoxy-4-vinylphenol, guaiacol, ethyl palmitate and ethyl caprylate that might though pathways related to fatty acid biosynthesis and amino acid metabolism. However, these genera were negatively correlated with the production of indole. Additionally, the total volatile basic nitrogen (TVB-N) levels of Mei yu fermented during 3 days were within the limits of 25 mg TVB-N/100 g fish, with the contents of free amino acids and lipoxygenase activities were significant lower than that of 4 days\' fermentation. In view of food safety and flavor, it suggested that the natural fermented Mei yu at room temperature should be controlled within 3 days. This study highlights the application of absolute quantification to microbiome analysis in traditional fermented Mei yu and provides new insights into the roles of microorganisms in flavor formation during fermentation.