Changes in fatty acids and polar material of restructured low-fat or walnut-added steaks pan-fried in olive oil

The study aims to determine the influence of pan-frying on the fatty acid composition and fat content and alteration of functional restructured beef steaks. Low-fat (L, 2% fat), 20% walnut-added (W, 13% fat) and medium fat (M, 13% fat) steaks were prepared and fried in extra virgin olive oil. Pan-frying increased fat in L and W steaks and decreased it in M ones. Raw L and M steaks showed similar fatty acid profiles while W ones contained a lower percentage of saturated fatty acids (SFA) and monounsaturated fatty acids (MUFA) but a higher percentage of polyunsaturated fatty acids (PUFA). The fatty acid profile of fried steaks was between that of the raw steaks and olive oil. Several fatty acids (g fatty acid/100g edible steaks) were affected (p<0.001) by the frying×meat-formulation interaction. Linoleic and linolenic acid contents did not decrease in fried W steaks, but decreased (p<0.05) when data were expressed on a dry matter basis. Frying increased SFA, MUFA and ω-6 PUFA contents in L samples while it decreased SFA and increased ω-6 PUFA in M steaks. Before and after frying, W steaks had atherogenic and thrombogenic indexes at least three times lower than their counterparts. Both indexes decreased in fried L samples while only the AI in M ones. Polar material content (PM) increased only in L samples. No relevant differences were found between PM of the fried steaks and that of their corresponding used oils. Results suggest that pan-frying improves the fatty acid composition of L and M steaks with minor changes in PM. The high retention of lipids observed in the W samples permits consumption of ω-3 PUFA- and ω-6 PUFA-enriched meat with a very low content of alteration compounds.