Proximate and fatty acid composition in raw and cooked muscle tissue of farmed rainbow trout (Oncorhynchus mykiss) fed with commercial fishmeal

The effects of four different cooking methods (steamed, boiled, deep‐fried, and grilled) on the proximate and fatty acid composition of rainbow trout were determined. The loss of water during the treatments increased the ratio of total fat and protein. The total content of polyunsaturated fatty acids (PUFAs) showed a significant change, increasing in the grilled samples. In contrast, there were no significant changes in the total amount of saturated and unsaturated fatty acids. The results showed that the major free fatty acid content in all the treatments was palmitic (C16:0), oleic (C18:1n9c), and linoleic acids (C18:2n6c). In addition, eicosapentaenoic acid (EPA) (C20:5n3) and docosahexaenoic acid (DHA) (C22:6n3) were the predominant n‐3 PUFAs in both the raw and cooked samples, but they were detected at low concentrations. Moreover, no significant change was observed in the n3/n6 ratio in all treatments. The highest index was 0.9026 ± 0.1804 in the grilled samples. Practical applications Fish farming plays a crucial role in boosting rural development and reducing poverty and hunger The vast majority of Atlantic salmon and rainbow trout consumed around the world are farmed intensively. However, the environment and feeding of the farmed fish is not the same in the different fish farming, causing changes in the nutritional values of the fish. In addition, the consumers have a minimal knowledge about the effect of the cooking method on the nutritional value. For this reason the study of the proximate and fatty acid composition of raw and cooking fish with a specific diet will help to professionals and fish farmers to improve the nutritional value of fish and the consumer could choose the healthiest cooking method.