Relationship between microorganisms and milk metabolites during quality changes in refrigerated raw milk: A metagenomic and metabolomic exploration

Although cold storage at 4 °C can effectively prolong the shelf life of raw milk, it cannot prevent its eventual spoilage. In this study, we analyzed the main physicochemical and microbial indexes of raw milk stored at 4 °C for 6 days. The changes in microbial profiles and milk metabolites and their relationship during refrigeration were also explored. Metagenomic analysis performed using the Illumina Hiseq Xten sequencing platform revealed that the dominant genera in raw milk evolved from Acinetobacter, Streptococcus, Staphylococcus, and Anaplasma to Flavobacterium, Pseudomonas, and Lactococcus during cold storage. Using the UHPLC-Q-TOF MS method, 77 significantly different metabolites (p