Comparison of nutritional value base on alpha linolenic acid and some heavy metal contamination in farmed rainbow trout and tuna fish in markets

Considering the importance of the role of nutrition for the health and the prevention of diseases, food should first be examined for the chemical and microbial safety and then for the amount of bioactive components according to the factors affecting its stability. In other words, the presence of nutrients in the food substance cannot be a reason to supply all of these resources to the body by reducing of bioactive content from the farm to the table. For this purpose, nutritional characteristic base on alpha linolenic acid (ALA) and human health risk base on some heavy metal as lead, mercury, cadmium in rainbow trout and tuna fish with respect to storing time in refrigerator and heat treatment method were analyzed by gas chromatography and atomic absorption spectrometry, respectively. Data were analyzed by T test in SPSS software. The results showed that the amount of heavy metals in these two fish species is less than the permissible FAO/WHO levels. But the accumulation of these metals in the rainbow trout skin was higher than the muscle. (P≥0.05). In tuna fish, sterilization heating could not obviously effect on the amount of heavy metals contents (P≥0.05). The mean percentage value of the ALA reduction in farmed rainbow trout was 11.9% in 5th day in refrigerator away from light that wasn’t usually used in markets. Sterilization heating in tuna fish processing has significant effect on ALA reduction (P≤0.05). Eventually, ALA content was decreased by storage time and processing method in farmed rainbow trout and tuna fish and ALA amount in farmed rainbow trout was higher than tuna fish (P≤0.05) which could be due to difference in species, nutrition addition to environmental factors such as fishing time, transport and storage conditions.