Quality of ready-to-eat swordfish fillets inoculated by Lactobacillus paracasei IMPC 2.1

BACKGROUND: Quality of marinated swordfish ready-to-eat (RTE) fillets, with or without inoculation of probiotic strain Lactobacillus paracasei IMPC 2.1, was assessed over 3 months of refrigerated storage at 4°C. Fish fillets from probiotic-inoculated and control RTE samples were sampled at 7, 14, 30, 60, and 90 days of storage. Microbiological tests, fatty acid (FA) profiles and malondialdehyde content were examined. Microbiological counts, including total viable count, lactic acid bacteria (LAB), yeasts and moulds, Enterobacteriaceae and Pseudomonadaceae were determined. RESULTS: Inoculation successfully ensured the growth of the probiotic strain, preventing the growth of other LAB types. The two RTE products showed significant differences in lipid profile and lipid oxidation along storage. In particular, inoculation with L. paracasei IMPC2.1 increased the amount of polyunsaturated FAs, and limited the amount of monounsaturated FAs and oleic acid, as well as lipid oxidation, thus representing an interesting strategy to preserve fish fillets chemical quality and to alternatively deliver probiotics. CONCLUSION: Probiotic inoculation seemed to delay the fish flesh lipid oxidation and increased the retention of polyunsaturated FAs suggesting a potential application of this probiotic strain in the seafood industry.