Chemical and Microbial Quality Assessments of Some Economic Important Artisanal Fresh Water Fish Species ( Tilapia zilli, Clarias gariepinus, Chrysichthys nigrodigitatus and S. melanotheron ) in Selected Coastal Markets of Lagos State, Nigeria)

摘要

Nutritional qualities of some selected fresh water fish species sold for consumption in the Badagry, Epe, Ikorodu and Ojo areas of Lagos state, Nigeria was assessed to ascertain the wholesomeness and health risk associated with consuming the most common sort after fish in these locations. A total of 100 fish samples, Red belly Tilapia (T. zilli), African Mud Catfish (C. gariepinus), Silver Catfish (C. nigrodigitatus) and Black Chin Tilapia (S. melanotheron) (25 specimens each) with a weight ranges between 50-180 g, were collected from different locations. The samples were iced and taken to the Biochemistry and Pharmaceutical laboratory sections of the College of Medicine University of Lagos, Idi-Araba, Lagos, Nigeria. The iced samples were maintained in alternate layers of ice until spoilage was noticed. Chemical analysis was conducted using Spectrophotometer, Atomic Absorption Spectrophotometer, Sohxlet Extraction Apparatus, Thiobarbituric Acid (TBA), The Acid Value (AV), Peroxide Value (PV), Iodine value, Free Fatty Acids (FFA) and Saponification value were determined. The result indicates higher TBA (8.79 ± 0.05), (7.59 ± 0.06), (7.46 ± 0.04) and (6.99 ± 0.05) for T. zilli, C. nigrodigitatus, S. melanotheron and C. gariepinus respectively in Ojo Lagoon, higher iodine value (9.69 ± 0.01) for T. zilli in Ojo Lagoon; (8.75 ± 0.21), (9.35 ± 0.07) and (8.45 ± 0.07) for C. nigrodigitatus, S. melanotheron and C. gariepinus respectively in Epe Lagoon and the acid values (3.31 ± 0.04), (2.45 ± 0.04) and (3.79 ± 0.04) for T. zilli, C. nigrodigitatus and S. melanotheron respectively in Badagry Lagoon and (2.25 ± 0.04) in Ojo Lagoon were within the standard limits. Higher mean mould load recorded were (1.22×104), (1.78×103), (1.90×103) for C. gariepinus, S. melanotheron and T. zilli respectively in Ikorodu Lagoon, while (3.47×103) was recorded for C. nigrodigitatus in Badagry Lagoon. The results indicated a notable quality improvement leading to a high quality fish in terms of the taste, colour, odour, shelf life and market value. The high iodine value recorded in this study from different locations suggests that the fish species contain high level of unsaturated oil and as such could reduce the risk of heart diseases, high cholesterol, depression, anxiety, low immunity, cancer, eye disorders and ulcers in humans when consumed. None of the fish samples exceeded the mould load limit for fish thereby exhibiting no risk on public health; therefore the fish are wholesome and safe for human consumption.