FISHERIES RESEARCH INSTITUTE,MOA,TAIWAN

The proximate composition of Cobia (Rachycentron canadum) varies greatly and is difficult to discern by their appearance. In this study, a non-destructive electromagnetic (EM) scan method was applied to estimate the proximate composition of cobia. The predictive equations were obtained to assess the index of quality.Cobia, weighing 2880~8340 g, were scanned with an EM scan. The analytical results of the proximate composition indicated that the moisture content decreased while lipid content increased as the body weight of cobia increased. Results also showed a negative relationship between moisture and lipid contents (R² =0.965). Ash and protein contents of cobia showed no significant differences with the body weight level in this study (p > 0.05). The TOBEC (total body electrical conductivity) value, body weight, fork length, and proximate composition were used to develop feasible predictive equations. The R² values of the equation for moisture, lean body mass, ash, and protein were 0.981, 0.983, 0.941, and 0.984, respectively.The R² value of the predictive equation for lipids was lower at 0.784. To evaluate the feasibility of the equation by paired t-test, the body weight, fork length, and TOBEC value of moisture and lipid contents of six new samples were checked by the predictive equation and experimental measurements. Results showed no significant differences between them. It is feasible to use equations for non-destructive analysis to predict the proximate composition of cobia.