Institute of Animal Science, 2232 Kostinbrod, Bulgaria
Abstract.The changesinthefattyacidcompositionofthebackfatwerestudiedin ♀Younax ♂Pietrain pigs.Theanimalsweredividedintwogroups(vitaminE supplemented and control) and after slaughter, samples of the inner and outer backfat layers were taken, frozen and stored for a period of 6 months. Fatty acid composition was analysed in fresh backfat samples and after frozen storage of 3 and 6 months. The content of the major saturated and monounsaturated fatty acids differed significantly between the two layers of the backfat in both groups. In the inner layer we observed significantly higher proportion of C16:0 (P<0.01) and C18:0 (P<0.001) while C18:1 had higher content in the outer backfat layer (P<0.001). The differences were not dependent on the presence of vitamin E in the diet, suggesting no effect of the antioxidant on the metabolism of the fatty acids of the two backfat layers. The total amount of unsaturated fatty acids (UFA) was increased (P<0.001), higher values of UFA/SFA (P<0.001) and lower of the atherogenic (AI) and thrombogenic (TI) indices (P<0.001) were observed in the outer backfat layer in both groups. The duration of frozen storage affected significantly the content of the individual and total fatty acids, as the changes were observed mostly between the 3rd and 6th month of frozen storage. In both groups the content of C16:0 and the total saturated fatty acids (SFA) decreased while the content of the total amount of UFA increased by the end of the 6th month. In the group supplemented vitamin E, the content of C16:1 significantly decreased (P<0.01) and that of C18:1 significantly increased (P<0.01) by the 6th month of storage. The atherogenic and thrombogenic indices followed the same pattern, showing the lowest values at the 6th month of frozen storage in both groups, thus indicating no negative influence on the duration of storage on the backfat.