Muscle fiber and fatty acid profiles of Mertolenga-PDO meat

The influence of phenotype and muscle type on intramuscular total lipids (ITL) neutral lipid (NL) and phospholipid (PL) compositions, cholesterol, α-tocopherol and haem iron contents were evaluated in Semitendinosus (St), Longissimus dorsi (Ld) and Supraspinatus (Ss) muscles from 39 Mertolenga young bulls. The results showed that lipid, α-tocopherol, cholesterol and haemic iron contents were not influenced by phenotype. Furthermore, the individual effect of phenotype was not a significant source of variation on ITL, NL and PL fatty acid composition. Muscle histological traits from Unicolor phenotype (n = 13) showed that Ss and Ld muscles exhibited higher proportion of type I (P < 0.001) and oxidative fibers (P < 0.001) and lower percentages of IIB fibers (P < 0.001) than St. The Ss muscle, with higher relative area occupied by oxidative fibers (P < 0.05–0.001) than Ld and St, had higher ITL (P < 0.001), NL (P < 0.001), PL (P < 0.05–0.01), α-tocopherol (P < 0.001), cholesterol (P < 0.01) and haem iron (P < 0.001) contents than its counterparts. Muscle type notably affected ITL, as a result of its influence on NL rather than in PL composition.