Abstract
The effects of smoking, boiling and freezing on the nutritional value and health risks of heavy metals in four fish species consumed in Douala was investigated. Fish samples from Cyprinus carpio, Arius parkii, Ethmalosa fimbriata and Polydactilis quadrifilis were collected at the Douala Fishing seaport, carried to the laboratory, washed with distilled water and processed. Proximate composition, mineral content, heavy metals and lipid quality were analyzed using AOAC standard methods. Estimated Daily Intake (EDI), Targeted Hazard Quotient (THQ), Hazard Index (HI) and Carcinogenic Risk (CR) were used to estimate the human health risk. Results showed that smoking and boiling increased significantly (P < 0.05) protein and ash levels. Lipid were reduced significantly (P < 0.05) with boiling and freezing compared to raw and smoked sample. Smoking increased significantly (P < 0.05) cadmium, lead, mercury and arsenic contents compared to boiling and freezing. EDI values of cadmium in all species of fish smoked were not acceptable for human consumption. THQ values of mercury in raw, smoked, boiled and frozen were not acceptable for human consumption. HI suggested a non potential carcinogenic effect for all fish while CR for cadmium and arsenic suggested a carcinogenic health risk for Arius parkii (smoked and boiled). All treatment decreased significantly (P < 0.05) iodine value and increased acid, peroxide, anisidine values, thiobarbituric acid reactive substances and total oxidation index compared to raw fish. Boiling was the best cooking method compared to smoking.