Effect of some Processing Methods on the Proximate Composition of some Frozen Marine Fishes

Fish being a significant protein contributor to our daily diet, is cheap to afford but is highly perishable due to change in climatic conditions and a favourable medium for the growth of microorganisms and hence processing method is important to extend the shelf life and add value. Boiling, smoking, salting and sun-drying methods were used to assess proximate composition of Atlantic mackerel (Scomber japonicus), Round Sardinella (Sardinella aurita), and Horse mackerel (Trachurus trachurus). The steaming method was used for the boiling, cold method smoking was used for the smoking, salt sprinkling and open sun-drying methods were used for the salting and sun-drying. Each of the processed fish species were analyzed for the moisture content, dry matter, lipid content, crude protein content, ash content, and the nitrogen free extract. The moisture content, dry matter, crude protein, ash content, lipid and nitrogen free extract of salting and sun-drying method ranged between 36.23-60.98%, 34.02-63.77%, 35.08-56.71%, 5.00-12.20%, 5.24-5.43% and 26.72-53.42% respectively. The smoking method ranged between 46.30-60.49% of moisture content, 39.51-53.70% of dry matter, 52.73-59.87% of crude protein, 3.07-13.15% of the ash content, 6.10-7.95% of lipid and 22.52-36.25% of nitrogen free extract. The boiling method ranged between 47.47-57.27% of moisture content, 42.73-52.53% of dry matter, 35.93-65.60% of crude protein, 6.23-8.35% of the ash content, 5.09-6.23% of lipid and 26.77-50.69% of nitrogen free extract all against the raw fish species which also ranged between 51.50-62.89% of moisture content, 39.11-48.50% of dry matter, 48.55-55.67% of crude protein, 2.21-6.67% of ash content, 6.50-8.05% of lipid content and 30.55-38.85% of nitrogen free extract. The processing methods used (smoking, boiling, salting and sun-drying) showed no negative effect on the proximate composition after analysis. Boiling, smoking, salting and sun-drying processing method has more positive effect on the proximate composition of Trachurus trachurus than Sardinella aurita and Scomber japonicus.