Prevalence of Microorganisms and Suggestion for Potential Contribution of Microorganisms to Volatile Basic Nitrogen Production in Beef at Current Purchase Stages

This study investigated the prevalence of microorganisms related to meat quality and analyzed volatile basic nitrogen (VBN) levels in beef samples to suggest potential bacteria that might contribute to VBN production at current purchase stages using metagenomic analysis. Seventy beef samples were analyzed for coliform, Escherichia coli, enterohemorrhagic E. coli, Listeria monocytogenes, Salmonella, Staphylococcus aureus, total aerobic bacteria (TAB), Enterobacteriaceae, lactic acid bacteria (LAB), Pseudomonas spp., yeast and molds (YM), and psychrotrophic bacteria (PB). VBN levels ranged from 0.69 to 22.51 mg%. Microbiota from three samples with the highest and three with the lowest VBN levels were analyzed. S. aureus was detected in only one sample at 1.2 Log CFU/g. The cell counts for TAB, coliform, Enterobacteriaceae, LAB, Pseudomonas spp., YM, and PB were 5.1, 1.7, 2.6, 4.2, 1.9, 2.9, and 5.4 Log CFU/g, respectively. Microbiota analysis revealed that samples with high VBN levels had high relative abundances of Lactobacillus and Leuconostoc. This study showed that these relatively abundant LAB were potential bacteria that might contribute to producing more VBN in beef at current purchase stages. However, the potential bacteria were suggested only by metagenomic analysis with a limited sample size without considering the endogenous meat enzymes. Therefore, further research is necessary to identify and isolate these bacteria with a larger sample size while excluding VBN produced by endogenous enzymes. Additionally, environmental factors not included due to the limited objective of this study could also be considered in further research with the different objectives from this study.