Metabolomics reveals spoilage characteristics and interaction of Pseudomonas lundensis and Brochothrix thermosphacta in refrigerated beef

Pseudomonas lundensis and Brochothrix thermosphacta are key spoilage microorganisms in aerobically stored chilled meat. The present study aimed to investigate the physicochemical and metabolomic profiles of refrigerated ground beef inoculated P. lundensis (PL) and B. thermosphacta (BT) as mono- or co-culture (BP). P. lundensis was the dominant spoilage strain in the co-culture of ground beef. A large amount of TCA-soluble peptide, TVB-N and TBA were formed in the PL and BP, while acetion was mainly produced in the BT, as accompanied by the different sensory and color changes. Meat metabolome indicated that 95, 396, and 409 metabolites with significant differences, were identified in ground beef inoculated BT, PL, and BP, respectively. These differential metabolites covered 58 metabolic pathways, in which histidine metabolism was identified as an important pathway related to spoilage in the three groups. Specifically, creatine, inosine, anserine, uracil, alanine, glutamine, 3-methylhistidine and 3-hydroxycapric acid were enriched as potential spoilage biomarkers. Taken together, those findings reveal the complex and competitive interactions of their co-culture of B. thermosphacta and P. lundensis, which provided a comprehensive insight into microbial spoilage mechanism in chilled beef.