BACKGROUND: Nowadays essential oils with antioxidant properties are used in order to increase the shelf life of pre-cooked food. Objectives: This study was carried out to compare the effect of Cumin and three methods of cooking, frying, oven baking and steaming on oxidative changes of pre-cooked fillet of rainbow trout. Chemical (DPPH(1,1- Diphenyl- 2- picryl hydrazine) for Cumin and FFA (Free Fatty Acid), PV(Peroxide value), TBARS) ، Thiobarbituric acid reactive substances) and sensory indicators, were evaluated during  4 months storage at freezing temperatures. Methods: Fillet samples were treated with Cuminum cyminum EOs and BHT. The study was based on application of cooking methods, frying at 180° C for 4 min in sunflower oil, baked in the oven at 200 °C for 22 min and steamed at 200 °C for 22 min and oxidative changes were evaluated during the period of storage as frozen fillets. Results: The FFA formation showed increase in all groups, oven baked rainbow trout fillets gave the highest increase (P<0.05). The highest value of PV was obtained from fried fillets treated with C. cyminum EOs (4.92  ± 0.23 meq/kg). The TBARS values were not significantly different with fresh-raw fillet after cooking (P>0.05), but the treated samples with EOs generally showed slower oxidative changes than those of the untreated samples. Based on the sensory evaluation, fillet fried was found as a preferred cooking method and also, the additions of C. cyminum EOs have positive effect on sensory quality of baked rainbow trout. Conclusions: Differences in cooking methods includin frying, oven baking and steaming showed that rainbow trout fillet treated with C. cyminum EOs under the frying method are more desirable in terms of chemical changes and sensory analysis compared with the other treatments.

Fifteen samples of fish fillets were collected from different Egyptian markets to detect the residues of some heavy metals in them. The average weights of fish fillets samples were 250g. The samples were separately packed in polyethylene bag and sent to the laboratory for preparation and analysis. All equipment surfaces and utensils which used in this study were thoroughly cleaned with detergent, rinsed with water, dried and then rinsed with 2-propanol solution. The samples were stored at –2C prior to analysis. The mean levels of lead and cadmium in fish fillets collected from the Egyptian markets were 1.51  0.34 and 0.60 0.0.25 mg/kg; respectively. The concentration of lead in fish muscle were less than the permissible heavy metal limit in fish meat (2.0 mg kg) as stated by the World Health Organization, also these results were in line with the corresponding EU regulations. However the level of cadmium concentration was over than the heavy metal limits in fish meat (0.5 mg/kg) for the World Health Organization.