Nutrient content and carcass composition of South African mutton with a focus on bioavailability of selected nutrients

Abstract

South Africans frequently consume red meat as part of their diet. However the nutrient content of South African sheep meat is derived from other countries. The Red Meat Industry considered it essential to have more reliable data and thus the nutrient content of A2 South African lamb was recently determined and published. This is the next phase of the study in which the right sides of C2 mutton carcasses were used to determine the nutrient and physical (carcass) composition of each raw cut as well as the whole carcass by calculation. Eighteen mutton carcasses of the most commonly consumed breeds, namely Dorper and Merino, in South Africa were selected. The carcasses were obtained from large abattoirs form three mutton producing regions in South Africa namely Ermelo, the Karoo and Kalahari. Chilled carcass sides were subdivided into ten primal cuts. Three cuts (shoulder, loin and leg) from the left side were cooked in order to determine the nutrient composition thereof. The cuts were dissected into meat which consists of muscle and intramuscular fat, intermuscular - plus subcutaneous fat and bone in order to determine the physical composition per cut and for the whole carcass. Meat compromise of 63.2% of the carcass, with bone contributing to 20.5% and fat to 16.9%. Results showed differences in the physical composition of South African C2 mutton as it contains on average 47% less fat and 19% more lean muscle, when compared to previous published composition data. Three cuts (shoulder, loin and leg) from the left side were cooked in order to determine the nutrient composition thereof. Cooking resulted in an increase in the protein and cholesterol concentrations of the cooked cuts. Iron content was higher in the cooked loin and leg but decreased in the cooked shoulder. According to nutrient density, a 100g edible portion of the leg, loin and shoulder have a nutrient density higher than one for protein, iron, zinc and vitamin B12 indicating that these cuts are a good source of these specific nutrients. A 100g edible portion of the loin cut contained higher fat quantities than the cooked shoulder and leg cuts. The loin cut also had a higher cholesterol content at 70.8mg compared the 58.5mg cholesterol content in the shoulder and 57.9mg in the leg cut. However, these values were calculated with all associated subcutaneous fat and it is known that many consumers trim on plate, especially the loin cut. Considering the fact that significant differences were apparent between the current study and previous data derived from other countries, it emphasizes the importance of determining the nutrient composition of South African food products in order to increase the validity of the SA food composition tables. Food-based approaches targeting the relief of micronutrient deficiency usually encourage the consumption of animal foods together with the consumption of green leafy vegetables (GLV). The inclusion of GLV and red meat, two micronutrient rich foods, can be a strategy based on mutual supplementation to combat nutritional deficiencies as it has the potential to alleviate numerous micronutrient deficiencies including iron and vitamin A deficiency.