Abstract :
This investigation was designed to evaluate the effects of feeding either free range or in confinement using concentrated diets
with the same ingredients and oil source (5.5% of olive oleins) but with different antioxidant supplementation [control diet
with a basal level of a-tocopheryl acetate (control); 200 mg/kg synthetic all-rac-a-tocopheryl acetate (Eall-rac); 200 mg/kg natural
RRR-a-tocopheryl-acetate (ERRR-); flavonoid extract-enriched diet (AFlav); and phenolic compound-enriched extract (APhen)] on the
fatty acid composition and lipid oxidation of Iberian pig muscle longissimus dorsi. The a-tocopherol concentration was
significantly higher in muscles from free-range and ERRR- pigs than in muscles from Eall-rac pigs, and g-tocopherol was only
detected in muscles from free-range pigs. Longissimus dorsi muscles from free-range pigs had a significantly lower content of
saturated fatty acids and higher content of polyunsaturated fatty acids than muscles from the other five groups of pigs fed in
confinement; however, no significant effect on monounsaturated fatty acids was observed. No effect of dietary antioxidant
supplementation (synthetic or natural a-tocopherol, flavonoid extract, or phenol extract) on the fatty acid composition of
muscles was observed. A significant influence of dietary treatment on lipid oxidation was observed after 3 (P,0.01), and 7
and 10 (P,0.001) days of refrigerated storage, respectively. The lowest thiobarbituric acid-reactive substances (TBARS) values
were found in pork chops from the free-range and ERRR- groups, intermediate values from the Eall-rac group, followed by AFlav
and APhen, while the highest TBARS values corresponded to muscles from pigs fed the control concentrate. The source of
a-tocopherol had a significant effect on lipid oxidation (P,0.05), whereas the AFlav and APhen groups had similar TBARS values.
Keywords :
fatty acids , Iberian pigs , Oxidation , Phenolic compounds , Tocopherols
