Effect of cooking on physical, biochemical, bacteriological characteristics and fatty acid profile of Tilapia (Oreochromis mossambicus) fish steaks

摘要

Fish makes a vital contribution to the survival and health of a significant portion of the world’s population. Fish is especially important in the developing world. In some of Asia’s poorest countries people derive as much as 75% of their daily protein from fish. In West Africa, fish accounts for 30% of animal protein intake, and this number would be larger if the poor could afford to buy more. In the present study, the effect of cooking on the changes in physical, biochemical, and bacteriological characteristics and fatty acid profile of fresh tilapia (Oreochromis mossambicus) meat were studied. The physical parameters like color, textural and pH was analyzed, while the chemical parameters like Total Volatile Basic Nitrogen (TVB-N), Thiobarbutric Acid (TBA) value, fatty acid profile and bacteriological analysis like Total plate count (TPC) were also analyzed. Along with the physical, biochemical, and bacteriological parameters, proximate analyses like moisture, protein, fat and ash content were also analyzed to assess the nutritional quality of tilapia fish. A significant (p0.05) reduction in moisture and fat content was observed in cooked tilapia meat with increased protein and ash content. The parameters of color viz. lightness (L), redness (a), yellowness (b), hue angle (arcton, b/a) and saturation index (a*2+b*2)0.5 significantly changed (p0.05) in the cooked fish steaks. Textural profile analysis of tilapia fish steaks revealed significant decrease (p0.05) in hardness, adhesiveness, gumminess, resilience, cohesiveness and chewiness, with a slight increase in the springiness and stringiness. Cooking of tilapia fish steaks had a significant influence on the TBA content and microbial load. The levels of TBA, salt, TVBN and TPC of raw/fresh meat of tilapia, which were 0.77±0.01mg%, 0.58±0.01%, 3.57±0.01mg% and 4.9 x104 cfu/g, was changed to 1.61±0.06mg%, 0.41±0.01%, 3.59±0.01mg% and 1 x102 cfu/g respectively, after cooking. The fatty acid composition of the cooked tilapia fish steaks significantly decreased in the levels of monounsaturated fatty acids and increased the n-3-6 Poly-Unsaturated Fatty Acid (PUFA) ratio. While cooking significantly increased the contents of eicosa-pentaenoic acid (EPA) and decosa-hexaenoic acid (DHA) in tilapia meat, no significant (p0.05) impact was observed on the contents of decosa-pentaenoic acid (DPA). Therefore tilapia meat appears to be a valuable source of n-3 PUFAs.