Cooking method affects lipid quality of farmed salmon

Although pan-frying is a quick and easy way to prepare palatable foods, popular with consumers, it is also associated with undesirable changes in the frying medium and in the fried products.

Therefore, a team from the Institute of Nutritional Sciences at the University of Vienna in Austria investigated how different cooking methods affected the composition of farmed salmon fillets.

Consumers are being encouraged to eat more oily fish like salmon because they are excellent sources of the polyunsaturated fatty acids, eicosapentaenoic (EPA) and docosahexaenoic acids (DHA).

However, being unsaturated makes them susceptible to oxidation so Al-Saghir et al. measured the degree of lipid oxidation and the formation of cholesterol oxidation products (COP) in salmon fillets which had been steamed, or pan-fried with olive oil, without olive oil, with corn oil and with partially hydrogenated vegetable oil.

The salmon samples were fried for 6 minutes with or without the oils (3 minutes each side) or steamed for 12 minutes. Only very small changes were observed in primary and secondary oxidation products after cooking, and tocopherol levels also remained stable.

There were significant increases in the cholesterol oxidation products in the fat extracted from the salmon after the various cooking procedures, with steaming leading to the greatest increase (mainly because it was cooked for longer).

The sum of cholesterol oxidation products increased after the heating processes from 0.9 microg/g in the raw sample to 6.0, 4.0, 4.4, 3.3, and 9.9 microg/g extracted fat in pan-fried without oil, with olive oil, corn oil, partially hydrogenated plant oil, and steamed, respectively.

None of the cooking methods affected the levels of EPA and DHA in the salmon, and the type of cooking oil also had little influence on the outcome.

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Reference
Al-Saghir S, Thurner K, Wagner KH, Frisch G, Luf W, Razzazi-Fazeli E, Elmadfa I. (2004). Effects of different cooking procedures on lipid quality and cholesterol oxidation of farmed salmon fish (Salmo salar). Journal of Agricultural and Food Chemistry, 52, 5290-5296