Determination of trace metal, fat content and iodine value in canned fishes; sardine (Sardinella brasilienses) and mackerel (scomber scombus)

Abstract

Ibe Awodi* and Nsidibe C Nwokem

Fish is an important source of nutrients to man and is also useful for the production of animal-based foods. However,
there have reported cases of contamination of fifish products from natural or anthropogenic sources such as; agricultural activities, industrial wastes and others. The corrosion and leaching of heavy metals from cans use for the packaging of the products may contribute to the contamination of foods. The consumption of these contaminated foods has deleterious
effects on human health such as; cancer, respiratory diseases, and kidney failure among others. It is therefore pertinent to address this surging global crisis. This study conceived to examine the concentration of metal ions, , fat and iodine value of fishes consumed in Nigeria. The samples were obtained from a store in Zaria, Kaduna State. A flame-type atomic absorption spectrophotometer, AAS (VARIAN AA240FS Fast sequential model) was used for the analysis of trace metals (Ni, Cr, Cd) content
of the sample. The results for the trace metal analysis in mackerel gave the following mean concentrations; 0.39±0.14 mg/kg (Ni2+),0.16±0.02 mg/kg (Cr) and <0.01 mg/kg (Cd). The mean concentration of trace metals in sardine was found to be: 0.09±0.01 mg/kg (Ni), 0.01±0 mg/kg (Cr) and <0.01 mg/kg (Cd). The fat contents in the analyzed fish sample were 25.24±4.16 % and 0.09±0.01 % for mackerel and sardine respectively, while  the iodine values of oil in mackerel obtained was 114.84±3.59 I2/100 g and that of Sardine was 76.14±3.03 I2/100 g. The concentration of cadmium in the two fish samples, and the concentration of Cr ions in samples of sardine were both below the recommended limit by WHO. However, the concentration of Cr in Mackerel and the concentration of Ni2+ in the two fish samples were above the permissible limit by WHO.