Characterization of the spoilage strength of Aeromonas spp. to collagen-rich chilled meat: comparative analysis

Aeromonas spp. are commonly found in spoilage of chilled meat. Aeromonas salmonicida NCM 29 and A. salmonicida NCM 57 have been discovered the spoilage heterogeneity in degrading myofibrillar protein. In this study, the two strains were tested to uncover the discrepancy of meat spoilage in collagen-rich chilled meat and extracted collagen. The results revealed that chicken claws, riched in collagen, inoculated with NCM 29 showed higher values of total viable counts (TVC), total volatile basic nitrogen (TVB-N), pH, adhered cells, trichloroacetic acid (TCA)-soluble peptides, and protease activity compared to those inoculated with NCM 57. Furthermore, NCM 29 generated higher quantity of volatile organic compounds related to meat spoilage. The collagenase ((hemagglutinin protease (Hap)) secreted by NCM 29 has been identified as the key factor responsible for the observed discrepancies in spoilage, which gradually degraded collagen into peptides and hydroxyproline. The capacity of Hap to degrade type Ⅰ collagen in vitro indicated that it has apparent proteolytic activity, which could reduce the average particle size and alter secondary structure of collagen. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) further confirmed the degradation of the β-chain in collagen. These findings not only provide a theoretical basis for in-depth investigation of the meat spoilage mechanisms of Aeromonas spp., but also encourage us to take measures to avoid the spoilage of related bacteria such as Aeromonas spp. during the preservation process.