Effect of free-range rearing and α-tocopherol and copper supplementation on fatty acid profiles and susceptibility to lipid oxidation of fresh meat from Iberian pigs

The effects of the feeding system (free-range versus confinement) and the inclusion in concentrate feeds of alpha-tocopheryl acetate (alpha-TAc) (0.100 g kg(-1)) and copper (II) sulphate (0.125 g kg(-1)) or both on meat oxidative susceptibility, alpha-tocopherol, intramuscular lipid fraction fatty acid and volatile aldehyde contents were determined in Biceps-femoris muscle from Iberian pigs. m. Biceps-femoris from free-range-reared Iberian pigs showed a significantly higher oleic acid percentage in neutral lipids (p < 0.001) than muscles from pigs fed in confinement, whereas confinement-pig muscles yielded higher arachidonic acid percentage (p < 0.05) in intramuscular fat and linoleic acid percentage (p < 0.05) in polar lipids. Copper (II) sulphate supplementation did not show any significant effect on fatty acid composition of lipid fractions of the B. femoris muscle. alpha-TAc supplementation highly increased the a-tocopherol content of muscles (p < 0.01). Free-range-reared pigs had the highest muscle FF61-tocopherol concentrations (p < 0.001), reflecting the high content found in the pasture. Both free-range rearing and alpha-TAc supplementation reduced susceptibility to iron-ascorbate-induced peroxidation and reduced hexanal content (p < 0.001). A clear relationship between the susceptibility to iron-ascorbate-induced peroxidation and the ratio between the concentration of polyunsaturated fatty acids in polar lipids and alpha-tocopherol content was found. The present results suggest a beneficial effect on meat quality when rearing hogs outdoors. They further suggest potential benefits to dry-cured products elaborated from free-range pigs as a result of a lower lipid oxidative trend of the meat. (C) 1999 Elsevier Science Ltd. All rights reserved.