IMPACT OF CURING ON MICROBIAL PARAMETERS AND LISTERIA MONOCYTOGENES GROWTH IN FISH FILLETS

Fish curing allows to add value to the product. The process entails a loss of weight due to the evaporation of the water and determines a more tender texture and a stronger flavour to the product. Fish fillets, after curing, are directly exposed to air into the cabinets for up to 10 days where specific combinations of temperature, air speed and relative humidity are applied during time depending on the desired final product, which is in intended as ready to eat (RTE). During the production of fish fillets, we enumerated Total Bacteria Count (TBC) and Enterobacteriaceae as well as performed contamination with Listeria monocytogenes to estimate its growth potential. The analyses were performed on three different fish species: salmon (Salmo salar), tuna (Thunnus thynnus) and swordfish (Xiphias gladius) during the processing period. TBC counts ranged from 3.55 to 2.74 log CFU/g in salmon, from di 4.22 log CFU/g to 4.94 log CFU/g in tuna and 5.69 to 5.93 log CFU/g in sword fish at the beginning and at the end of the cycle, respectively. On the contrary, Enterobacteriaceae were not detected in any of the sample neither at the beginning nor at the end of the experimental trial. L. monocytogenes counts remained stable throughout the production cycle with a slight reduction towards the final stages. Our results underline how L. monocytogenes eventually present on raw material does not grow during processing, but we didn’t test the behavior of the pathogen along the product shelf life. In addition, even though TBC counts reached almost 6 log CFU/g in sword fish, neither were the Enterobacteriaceae ever detected, nor was evident spoilage of fillets