College of Biomass Science and Engineering, Sichuan University, Chengdu 610065, China; Key Laboratory of Leather Chemistry and Engineering, Ministry of Education, Sichuan University, Chengdu 610065, China.
College of Biomass Science and Engineering, Sichuan University, Chengdu 610065, China; Key Laboratory of Leather Chemistry and Engineering, Ministry of Education, Sichuan University, Chengdu 610065, China.
Int J Food Microbiol. 2024 Dec 2;425:110877. doi: 10.1016/j.ijfoodmicro.2024.110877. Epub 2024 Aug 17.
Paocai is a traditional Chinese fermented vegetable product popular in Asian countries. Recently, functional starters were used to control the fermentation process and improve the quality of paocai. In this study, three autochthonous lactic acid bacteria including Lactiplantibacillus plantarum LB6, Lactiplantibacillus pentosus LB3, and Weissella cibaria W51 were selected as starters and the effect of the starters on the fermentation of paocai was investigated. The results suggested that the inoculated fermentation led to a lower nitrite peak and more pronounced changes in pH and total titratable acid in the early stage of fermentation, compared with natural fermentation. Analysis of the flavor compounds indicated that the total content of volatile organic compounds of paocai through natural fermentation was significantly lower than that in inoculated fermentation. As for free amino acids, in the early stage of fermentation, the types and contents of free amino acids in the inoculated fermentation paocai were higher than those in the blank group. In the later stage of fermentation, the contents of amino acids representing umami and sweet tastes were also higher than those in the blank group. The bacterial community analysis showed that Lactobacillus and Lactococcus were the dominant bacteria in both inoculated fermentation and natural fermentation. Then, the correlations among physicochemical properties, microbial community and flavor compounds were revealed, and it was found that the dominant bacteria such as Lactococcus, Leuconostoc, Lactobacillus and Weissella displayed a considerable impact on the physical and chemical properties and flavor of paocai. In addition, the metabolic pathways involved in flavor formation and the abundance of related enzymes were elucidated. The abundance of enzymes involved in generating prephenic acid, 2-methylbutanoic acid, L-lactic acid, D-lactic acid, butanoic acid, etc., and in the pathway of producing flavor substances (His, Met, ethyl hexanoate, etc.) was up-regulated in the inoculated fermentation. Results presented in this study may provide a reference for the development of paocai starters and further guidance for the flavor improvement of Sichuan paocai.
泡酸菜是一种流行于亚洲国家的传统中国发酵蔬菜产品。最近，功能性发酵剂被用于控制发酵过程并提高泡酸菜的质量。在这项研究中，选择了三种本土植物乳杆菌 LB6、戊糖片球菌 LB3 和魏斯氏菌 W51 作为发酵剂，研究了发酵剂对泡酸菜发酵的影响。结果表明，与自然发酵相比，接种发酵导致发酵初期亚硝酸盐峰值较低，pH 值和总可滴定酸度变化更为明显。风味化合物分析表明，自然发酵泡酸菜的挥发性有机化合物总量明显低于接种发酵。对于游离氨基酸，在发酵早期，接种发酵泡酸菜中的游离氨基酸种类和含量均高于空白组。在发酵后期，代表鲜味和甜味的氨基酸含量也高于空白组。细菌群落分析表明，乳酸菌和乳球菌是接种发酵和自然发酵中占优势的细菌。然后，揭示了理化性质、微生物群落和风味化合物之间的相关性，发现乳酸菌、乳球菌、乳杆菌和魏斯氏菌等优势细菌对泡酸菜的理化性质和风味有相当大的影响。此外，还阐明了风味形成涉及的代谢途径和相关酶的丰度。参与生成预苯酸、2-甲基丁酸、L-乳酸、D-乳酸、丁酸等的酶的丰度以及产生风味物质（His、Met、乙基己酸酯等）的途径中的酶的丰度在接种发酵中上调。本研究的结果可为泡酸菜发酵剂的开发提供参考，并为四川泡酸菜的风味改善提供进一步的指导。
