Supranutritional vitamin E supplementation in pigs:: Influence on subcellular deposition of α-tocopherol and on oxidative stability by conventional and derivative spectrophotometry

The influence of three levels of vitamin E (30, 200 and 1000 mg kg(-1)) in the diet of pigs on the subcellular deposition of alpha-tocopherol in muscle and on the oxidative stability determined by conventional and first derivative spectrophotometry was studied. The content of a-tocopherol in m. gluteo biceps and in mitochondrial and microsomal fractions of the muscle significantly increased (p < 0.01) with increasing levels of dietary vitamin E. Concentrations of a-tocopherol in muscle, mitochondria and microsomes of pigs fed diet supplemented with 1000 mg kg(-1) alpha-tocopheryl acetate were 3.2-, 6.1- and 5.6-fold greater, respectively, than those in their counterparts from the control animals. These differences in alpha-tocopherol concentration in the subcellular fractions and intact muscle resulted in enhanced stability of the membranes and the tissue when exposed to iron-ascorbate induced peroxidation. When lipid oxidation in the same samples was further measured by the first derivative method, the resultant MDA-TBA values were 59-69% lower in tissue samples, 16-19% lower in mitochondria and 6-9% lower in microsomes than the conventional TEARS values. (C) 1997 Elsevier Science Ltd. All rights reserved.