Increase of geometrical and positional fatty acid isomers in dark meat from broilers fed heated oils.

Oxidation of polyunsaturated fatty acids leads to primary and secondary oxidation products. Compounds and amounts of these products vary, depending on the oxidative conditions. Because these oxidation products have different absorption and biological effects, we performed 2 different heating treatments on sunflower oil. The first was heating the oil at 190 to 195 degrees C for 28 h (i.e., very oxidized oil), and the other was heating at 60 degrees C for 12 d (i.e., peroxidized oil). In the frame of this study, we compared the fatty acid composition of a refined sunflower oil (fresh oil), peroxidized oil, very oxidized oil, and a mixture (1:1) of fresh and very oxidized oil (i.e., oxidized oil). Oil fatty acid compositions were affected by the heating treatments. In addition, different fatty acid isomers were formed during heating at 190 to 195 degrees C, and significant differences were found between their contents in the sunflower oils. We also studied the effect of feeding broilers with these oils and Zn and tocopherol supplements on the fatty acid composition of their raw dark meat. Various trans fatty acid isomers increased in dark meat from broilers fed oxidized and very oxidized oils. In addition, discriminant analysis showed that ditrans-conjugated linoleic acid content was able to distinguish dark chicken meat from chickens fed sunflower oils heated at 190 to 195 degrees C.