Effect of Processing and Storage on the Trace Metal Concentration and Freshness Quality of Catfish (Clarias gariepinus)

Abstract

The freshness quality of fish is altered by enzymatic and microbial activities, necessitating the application of fish preservation technology. This study assessed trace metals concentration and freshness quality of Catfish (Clarias gariepinus) preserved by oven-drying, brining/oven drying and smoking. The fish were processed to average moisture contents of 15 ± 5 %. Processed fish samples were stored in perforated plastic containers for 11 successive weeks at room temperature and assessed weekly for levels of trace metals (Fe, Zn, Cd, Pb) and physical attributes of odour, flavour and texture. Microbial load was assessed by total viable count (TVC) and biochemical activity by total volatile nitrogen (TVN). The freshness quality of processed fish decreased with increasing storage time and all samples preserved using the three preservation methods contained levels of trace metals below the recommended limits for trace metals in fish and are therefore safe for human consumption.

Keywords: Preservation, trace metals, freshness quality, total viable count, total volatile nitrogen