Microbial load of some imported frozen fish species in Lagos, Nigeria

Abstract

Freezing preserves food by stopping the growth and multiplication of microbes or by halting enzymatic activities in foods that would otherwise cause spoilage. This study was conducted to identify and profile the microbes present in frozen fish. Five frozen fish species, Trachurus trachurus, Scombers combrus, Larimichthys crocea, Gadus chalcogrammus and Oreochromis niloticus, were purchased from Ijora–Olopa frozen fish sales  outlet in Lagos State and transported in ice-flakes to the laboratory for microbiological analysis of the skin, muscles and gills. S. scombrus and G. chalcogrammus had the highest (5.30 x 102 cfu/g) and lowest microbial loads (1.85 x 102 cfu/g) respectively. The result however showed that L. crocea and G. Chalcogrammus were noticed to be significantly different (P<0.05) for coliform count on both the skin and the gills. These values were much higher than the recommended public health and safety standard values that ranged from 5.0 × 105and 1.0 × 106CFUg-1, approved by Nigerian National Agency for Drug Administration and Control (NAFDAC). Hence, it is necessary that frozen foods should be properly cooked before consumption and effective hazard analysis and critical control points implemented. The predominant bacteria species isolated were Bacillus subtilis, Pseudomonas sp., Staphylococcus aureus, E. Coli and Salmonella sp while the predominant fungal species isolated were Apergillus flavus, A. fumigatus, A. niger and Yeast.

Keywords: Frozen fish, gills, muscles, skin, bacteria, fungi,