Abstract
The effect of temperature (0-15°C) and CO 2 (0-80%) on the growth of spoilage bacteria (total viable count, Pseudomonas sp. and lactic acid bacteria) in marine cultured gilthead seabream fillets was studied and kinetically modelled using an Arrhenius type equation. Pseudomonas sp. dominated the spoilage microflora of aerobically packed fillets whereas LAB defined spoilage at the MAP conditions. Modified atmosphere packaging led to a significant shelf-life extension of fillets, in terms of microbial growth and organoleptic deterioration. The preservative effect of CO 2 was greater as the CO 2 concentration in the atmosphere increased. Under this context, MAP can practically extend the shelf life of chilled gilthead seabream fillets. The growth of LAB was modelled as a function of temperature and CO 2 concentration in modified atmosphere packaging. The applicability of the models was validated at fluctuating temperature conditions. The nominal maximum CO 2 concentration (CO 2,max) for growth and the specific growth rate (k ref) at T ref (4°C) in the absence of carbon dioxide were determined to be 98.3% and 0.015 h -1, respectively. The activation energy parameter of the model, which indicates the temperature dependence of the growth rates, was 101.0 kJ/mol showing a strong dependence of LAB growth on storage temperature. Based on organoleptic acceptability the end of shelf life coincided with 10 7/g Pseudomonas sp. and 10 6/g lactobacilli for aerobically and MAP stored samples respectively. Based on the developed models this translates to 7, 8, 12 and 32 days of shelf life at 5°C and 0, 20, 50 and 80% CO 2 respectively.