State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu 214122, China; School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu 214122, China.
School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu 214122, China.
J Dairy Sci. 2021 Dec;104(12):12375-12393. doi: 10.3168/jds.2021-20654. Epub 2021 Sep 3.
Rushan is a traditional dairy product consumed by the Bai people in the Yunnan Province of China, and its production still follows the traditional procedure of backslopping. However, how the microbial composition of raw materials and processing shape the microorganisms in rushan have not been systemically reported. In this study, high-throughput sequencing technique was applied to analyze the microbial compositions of raw milk, fresh rushan, curd whey, acid whey, and dry rushan at the phylum, family, genus, and Lactobacillus species levels. The results indicated that Lactobacillus, Lactococcus, and Streptococcus were dominant genera in rushan, whereas Lactobacillus kefiranofaciens and Lactobacillus helveticus were the 2 abundant species at the Lactobacillus species level. The network analysis indicated that raw milk mainly contributed to the microbial diversity of rushan, whereas acid whey made a great contribution to shaping the relative abundance of microbes in rushan and dramatically increased acid-producing genera, such as Lactobacillus and Acetobacter. The variation in microbial composition led to an increase in the relative abundance of pathways related to energy supply, acid production, fatty acid accumulation, cysteine, methionine, and lysine accumulation. The volatile profile of rushan was rich in esters and acids, and the high relative abundance of Lactobacillus might be associated with reduction of amino acid metabolism, degradation of unpleasant flavored xylene, and accumulation of decanoic, dodecanoic, and tetradecanoic acids in the products. The accumulation of medium long-chain fatty acids might result from the relative abundance of FabF, FabZ, and FabI, particularly from Lactobacillus amylolyticus and Lacticaseibacillus paracasei.
乳扇是中国云南省白族的一种传统乳制品，其生产仍然遵循传统的回锅工艺。然而，原料的微生物组成和加工过程如何塑造乳扇中的微生物尚未得到系统报道。在这项研究中，应用高通量测序技术分析了生乳、新鲜乳扇、凝乳乳清、酸乳清和干乳扇在门、科、属和乳杆菌种水平的微生物组成。结果表明，乳扇中优势属为乳杆菌属、乳球菌属和链球菌属，而乳杆菌属 kefiranofaciens 和乳杆菌属 helveticus 是乳杆菌属中最丰富的两个种。网络分析表明，生乳主要影响乳扇的微生物多样性，而酸乳清对乳扇中微生物的相对丰度有很大贡献，并显著增加了产酸属，如乳杆菌属和醋杆菌属。微生物组成的变化导致与能量供应、产酸、脂肪酸积累、半胱氨酸、蛋氨酸和赖氨酸积累相关的途径的相对丰度增加。乳扇的挥发性成分富含酯类和酸类，乳杆菌属的相对丰度较高可能与氨基酸代谢减少、令人不快的二甲苯降解、以及癸酸、十二酸和十四酸的积累有关。中长链脂肪酸的积累可能是由于 FabF、FabZ 和 FabI 的相对丰度较高，特别是由于淀粉乳杆菌和副干酪乳杆菌的存在。
