Carcass grading effects on the fatty acid and amino acid composition of pork loin from Duroc pigs

Eighty purebred Duroc pigs slaughtered at 210 d of age were used to evaluate the effect of carcass grading according to lean content (R, 45-50%, n = 18; O, 40-45%, n = 28; P, < 40%, n = 34) on the fatty acid and amino acid composition of fresh pork loins. The crude protein content of loin was higher while the intramuscular fat content was lower in R carcasses than in the rest (P < 0.05). Carcass group had a major effect on fatty acid composition, with R carcasses showing lower MUFA and greater PUFA content than the rest of groups (P < 0.05) and with similar SFA content across groups (P > 0.05). Amino acid composition was not affected by carcass grading except for a tendency for isoleucine and glycine to have lower levels in P and R carcasses, respectively (P < 0.1). The balance of amino acids in the pork loin was compared with the recommended balance of indispensable amino acids for adults (WHO/FAO/UNU) by expressing the relevant amino acids relative to lysine and then calculating the proportion of the recommended amount of each amino acid that was provided by a sample containing the recommended amount of lysine. The balance of indispensable amino acids was less than ideal, with valine being the limiting amino acid by about 30-35%, indicating that consumption of 144-151 g of pork loin would be needed to match 100 g of a sample with the recommended balance of the indispensable amino acids. The amount of Duroc pork meat that would need to be consumed to get a satisfactory balance of amino acids was highest in the P (< 40% lean) carcass grade group. In conclusion, in the Duroc swine breed, carcass adiposity modifies the fatty acid profile of meat but hardly affects the amino acid balance of raw loin.