Specific spoilage bacteria in cold chain logistics: A study on ATP-related compounds degradation in large yellow croaker (Larimichthys crocea)

Abstract

This study evaluated the contribution of three spoilage bacteria (Shewanella putrefaciens (S. putrefaciens), Pseudomonas fluorescens (P. fluorescens), and Aeromonas salmonicida (A. salmonicida)) to the degradation of adenosine triphosphate (ATP)-related compounds in fish juice and fillet systems of large yellow croaker during cold chain logistics. The contribution of spoilage bacteria was explored by determining the microbial counts, ATP-related compounds, and associated enzyme activities. The results revealed that the S. putrefaciens, P. fluorescens, and A. salmonicida have the highest activities in 5′-nucleotidase (5′-NT), acid phosphatase (ACP), and alkaline phosphatase (AKP), with 49.78, 162.24, and 142.3 U/gprot, respectively. The rapid degradation of inosine monophosphate (IMP) occurs with increasing 5′-NT activity. It indicates that S. putrefaciens, P. fluorescens, and A. salmonicida mainly secreted 5′-NT, ACP, and AKP to degrade IMP, respectively, and that 5′-NT was the key enzyme in degrading IMP. All three are notable producers of purine nucleoside phosphorylase (PNP) and xanthine oxidase (XOD). The results showed that S. putrefaciens is the primary bacterium in the pre-degradation phase of ATP-related compounds, and A. salmonicida presumably dominates in the post-degradation phase. This study offers critical insights into the research on spoilage mechanisms of marine fish throughout the cold chain logistics.