Microbiological assessment and the potential antimicrobial activities of nisin and\or garlic extract in commercial fish

Abstract

Fish is considered as a major source of animal-derived protein. However, fish is a perishable food that rapidly decomposed and its initial microbial load determines the extent of spoilage. The objectives of this study were firstly to screen the microbial status of three commonly consumed fish species in Egypt, namely, tilapia, mullet and catfish via estimation of total plate counts, total psychrophilic counts, most probable number of coliforms and total mould counts. Secondly, an experimental trial to investigate the antimicrobial potentials of either nisin, garlic extract or an equal mixture of them using tilapia fish as a food matrix. The results achieved in this study declared that, the insufficient hygienic measure adopted during handling, marketing and storage of fish, in terms of the high microbial load. Catfish had the highest bio- indicator parameters followed by tilapia and mullet. Both of nisin and garlic extracts showed significant antimicrobial properties in a concentration- dependent manner. In particular, the synergistic effects of the co-treatment of both nisin and garlic extract were documented. Thus, efficient hygienic handling, rapid cooling of fish can reduce the initial microbial load of fish. In addition, we highly recommend soaking of fish in nisin, garlic extract or both as an efficient strategy in reducing the microbial load of raw fish. Furthermore, efficient cooking of fish can prevent the intake of food-borne pathogens.