Changes of lipid oxidation indices and fatty acids composition of salted fillet of grass-carp Ctenopharyngodon idella affected by methods of cooking

Lipid content and poly-unsaturated fatty acids changes of salted Grass-Carp fillet were evaluated as affected by methods of cooking. For this purpose, raw, dry-salted (by 24% salt) and cooked fillets (fried, boiled, microwaved and grilled) were evaluated, qualitatively. The results showed that salting and frying both increased the lipid content (p<0.05). All of cooking methods increased oxidative indices, but frying increased PV (by 4.66 meqO2/kg) and had a lower decreasing on TBA (by 0.525 mgMDA/Kg) and cooking by microwave had higher increasing on FFA (by 1.99 %). In addition, during salting process UFA, PUFA and ω-6 fatty acids were increased but total high chains of EPA+DHA and Polyen Index (PI) were decreased (p<0.05) that showed the salting effect on them, while had no effect on ω-3 (p>0.05). On the other hand, frying, among of cooking methods, decreased SFA, (29.79 to 22.93%), highly and instead UFA (55.57 to 71.16%), considerably that indicate diffusion of oil into the fish tissues. Frying also increased ω-6 (16.18 to 36.13%) amount (p<0.05) but has no effect on ω-3. All of the cooking methods decreased PI because of the thermal process (p<0.05). Boiling method just down to reduce of salted fillets ω-3 (2.15 to 1.44%). Also, cooking by microwave can decrease PUFA and PI, but has no effect on the other importance salted Grass-Carp fillet and finally the grilling had none effect on UFA, PUFA, ω-3 and even ω-3 fatty acids, and only decreased total EPA+DHA (from 1.06 to 0.49%) (p<0.05). However, none of the usual fish cooking methods didn't lead to lipid qualitative spoilage.