Effect of different cooking techniques on the nutritional quality of trout and whiting

Fish lipids contain large amounts of eicosapentaenoic (EPA 20:5 n-3) and docosahexaenoic (DHA 22:6 n-3) acids. Epidemiological studies stating an inverse correlation between ischemic heart disease and fish consumption never considered the fatty acid composition changes due to cooking. This research is aimed towards an evaluation of the effect of cooking on the fatty acid composition of two fish species (a fresh-water trout and a salt-water whiting). For cooking we chose a traditional system like convection electric oven and a more innovative one like microwave oven. Tissue lipids were extracted by the method of Folch and the fatty acids were transformed into their methylesters for GLC analysis. The fatty acid compositions of both fish species before and after cooking were statistically analysed by Student's t test. Our results showed that trout contains more fat than whiting but less n-3 fatty acids. Furthermore, unsaturated fatty acids were shown to be more stable after microwave cooking, as confirmed by P/S and M/S ratios