Different effects of super-chilling and chilling storage on pork spoilage: Insights from dynamic microbial community...

Super-chilling can extend the shelf life of high-oxygen modified atmosphere packaged (MAP) pork from 14 to 56 days compared to conventional chilling storage. The spoilage of raw pork may result from the growth of microorganisms, which ultimately release undesirable metabolites. To investigate this, the microbial and metabolic characteristics of super-chilled MAP pork were determined using 16S rRNA sequencing and untargeted metabolomics based on UHPLC-MS/MS. Dominant spoilage bacteria identified in super-chilled MAP pork (Leuconostoc, Trueperella, Carnobacterium, and Massilia) differ from those in the chilling MAP pork (Brochothrix, Pseudomonas, and Serratia). Metabolomics analysis shows that the different metabolites (DMs) in the super-chilling group contained more lipids and lipid-like molecules, while the DMs in the chilling group contained more organic acids and derivatives. WGCNA reveals that most metabolites in super-chilled MAP pork are correlated to Leuconostoc and Trueperella. According to the KEGG analysis, twenty-nine metabolic pathways were discovered as potential mechanisms underlying the spoilage of super-chilled MAP pork, encompassing lipid, amino acid, and nucleotide metabolism. Random forest analysis identified 63 critical metabolites as spoilage biomarkers, in which 43 metabolites (containing amino acids, lipids, hypoxanthine, xanthine, and nicotinic acid et al.) and 18 metabolites (containing IMP, lactate, and carbohydrate and their phosphorylated products) may be metabolites and substrates of these spoilage bacteria, respectively. This study provides new insights into the changes in microbial and metabolic characteristics that occur during the spoilage of super-chilled MAP pork.