Growth and spoilage metabolites production of a mesophilic Aeromonas salmonicida strain in Atlantic salmon (Salmo salar L.) during cold storage in modified atmosphere

AIMS: The aim of the study was to quantify the growth kinetic parameters and spoilage-associated metabolites of an inoculated strain of Aeromonas salmonicida in pre-rigor filleted Atlantic salmon (Salmo salar L.) stored in vacuum (VP) or modified atmosphere (MAP 60/40% CO2 /N2 ) at 4 and 8°C. METHODS AND RESULTS: The maximum growth rate of A. salmonicida in VP salmon stored at 4°C was 0·56 ± 0·04 day-1 with no detectable lag-phase and the concentration of Aeromonas reached 8·33 log CFU per g after 10 days. The growth rates and maximum population density of Aeromonas in MAP salmon were lower but the applied atmosphere did not inhibit the growth. A selection of metabolites associated with fish spoilage were quantified using 1 H nuclear magnetic resonance (NMR) spectroscopy. The concentration of trimethylamine (TMA) was significantly affected by storage time and temperature, packaging atmosphere and inoculation with A. salmonicida (General Linear Model (GLM), P < 0·001 for all factors). CONCLUSION: The study presents preliminary results on A. salmonicida as a potential spoilage organism in vacuum-packaged salmon during cold storage. The combination of refrigeration and a packaging atmosphere consisting of 60/40 % CO2 /N2 did not completely inhibit the growth but prevented the formation of TMA. SIGNIFICANCE AND IMPACT OF THE STUDY: Little information is available on the spoilage potential of Aeromonas spp. in minimally processed salmon products under different packaging conditions. The study clearly demonstrates the importance of hurdle technology and provides data to further elucidate the significance of Aeromonas spp. as a spoilage organism.