| Popis: |
The chemical composition of subcutaneous fat (backfat) from the last rib and shoulder regions was studied in 300 pig carcasses, mean weight 58 kg, falling into 3 fat-thickness groups averaging 8, 12 and 16 mm P2 (65 mm from mid dorsal line at last rib). The carcasses were obtained in 10 abattoirs, in each of which 5 producer groups of 6 pigs were identified: 1 entire male and 1 female for each of the fat-thickness groups. Concentrations of the gross constituents water, lipid and collagen were greatly affected by the thickness of backfat, water and collagen declining and lipid increasing through the fat thickness range. Fatty acids were less affected, although linoleic acid (C18:2) decreased from 14.9% of fatty acids at 8 mm P2 to 10.6% at 16 mm. The concentration of C18:2 measured at the last rib and shoulder positions was highly correlated with subjective and objective measures of tissue firmness at both sites. In each fat thickness group, backfat from entire males contained higher concentrations of water, collagen and C18:2 than that from females. Relationships between concentrations and P2 were curvilinear, changing most at low P2 levels, and were best explained by linear regressions of log components on log P2. Regression lines were parallel in the two sexes and were such that concentrations in entire males were similar to those in females with a 15% lower P2 value. Average values for polyunsaturated fatty acids were higher than standard figures normally quoted, the ratio of polyunsaturated to saturated fatty acids in the leanest group (0.41) being close to the recommended value for the U.K. diet as a whole. |
