Oxidation process affecting fatty acids and cholesterol in fried and roasted salmon.

Salmon was processed by three different culinary techniques: pan-frying with olive oil, pan-frying with soya oil, and roasting. Roasting did not modify the fat content from that of raw samples. Frying increased the fat content 2-fold, with no difference between samples fried with different oils. Total cholesterol oxidized products (COPs) were 0.74, 2.98, 3.35, and 7.38 microg/g fat in raw, fried with olive oil, fried with soya oil, and roasted salmon, respectively, which represent 0.01, 0.08, 0.09, and 0.15% of cholesterol. A significant correlation (r = 0.902, < or = 0.01) was found between acidity index and total COPs. The most abundant COPs were 7-ketocholesterol, which appeared in all the samples, and cholestanetriol (one of the most citotoxic COP), which appeared only in cooked samples (1.05-1.33 microg/g fat). All cooked samples supplied more omega-6 polyunsaturated fatty acids (PUFAs) than raw samples and showed higher omega-6/omega-3 ratios. Roasted salmon showed the lowest omega-3 content and the highest PUFAs/(SFAs)-C18:0 and MUFAs+PUFAs/(SFAs-C18:0) ratios.