Influence of processing methods on quality and stability of silver catfish (Chrysichthys nigrodigitatus)
The study assessed different processing methods (freezing, smoking, oven drying and boiling) on fillet nutritional quality and stability of silver catfish. All analyses followed standard procedure. Results of proximate composition showed significant increase (p< 0.05) in protein (51.98%), lipid (11.65%), ash (3.82%) and calorie (432.57 Kcal/g) contents in the dried fillets. Thus, these variable increased with increasing processing temperature. On the other hand, moisture and carbohydrate contents decreased with temperature. The stability indices showed significant differences (p < 0.05) in free fatty acid of frozen (0.21%), boiled (0.8%), smoked (2.96%) and dried (9.87%). The lowest calcium (39.7%) was recorded in the frozen sample while the highest level (53.12%) in oven dried. Thiobarbituric acid decreased with increase in processing temperature with the highest level (27.14 mg MDA/100g) observed in the frozen fillet while the least value (2.08 mg MDA/100g) was obtained in the boiled samples. Calcium and phosphorus contents did not show any particular trend. The smoked fish fillet had the highest fibre content of 2.6%. Total volatile base nitrogen was generally low in all treatments. Inference from this study revealed that differently processed Chrysichthys nigrodigitatus was a rich source of fatty acids and essential minerals being very vital to the diet of humans.