Potential uses of lactic acid bacteria in seafood products

Abstract

Lactic acid bacteria (LAB) have been used for centuries in the fish fermentation of a variety of seafood products. The preservative ability of LAB in seafood is attributed to the production of antimicrobial metabolites, including organic acids and bacteriocins. Bacteriocins generally exert their antimicrobial action by interfering with the cell wall or the membrane of target organisms, either by inhibiting cell wall biosynthesis or by causing pore formation, subsequently resulting in death. The incorporation of bacteriocins as a biopreservative ingredient into model food systems has been studied extensively and has been shown to be effective in the control of pathogenic and spoilage microorganisms. In seafood packed in both vacuum (VP) and modified atmosphere packaging (MAP), commonly CO2 enriched, the growth of the Gram-negative aerobic bacteria group (predominantly pseudomonads) is effectively inhibited and the number reached by LAB during storage is higher than that achieved in air, but is always several log units lower than the trimethylamine oxide (TMAO) reducing and CO2-resistant organisms (Shewanella putrefaciens and Photobacterium phosphoreum). In any case, the function of LAB in marine products is complex, depending on the species, strains, interaction with other bacteria, and the food matrix. They may have no particular effect or they may be responsible for spoilage and, in certain cases, they may even exert a bioprotective effect in relation to undesirable bacteria. The bioprotective potential of endogenous LAB in relation to pathogens and spoiling bacteria has often been highlighted. However, the technology is still in its infancy compared with dairy foods and meat products, in which either the carbohydrate content (dairy products) or sugar and salt added (meat products) favor the acidification by LAB that enable a natural preservation of the product. Successful studies on LAB as probiotics for fish have intensified, but this potential is still to be explored for humans. Although not usual, some applications of LAB for the fermentation of marine products and by-products are described.