Effect of age and cut on the nutritional content of South African beef

The physical composition and nutrient content of different age group carcasses and cuts of South African beef from equal fat classes were investigated. Carcasses from three different age groups and various fatness levels within each, were obtained on the commercial market. The physical composition of each right side cut (n=270) was assessed and analysed for raw nutrient content, while each left side cut was cooked prior to analyses. Physical composition of the carcass and cuts had the greatest effect on the difference between age groups, with meat and bone increasing with an increase in age. Protein increased (including eleven of the amino acids measured) and moisture content decreased with age in the cooked cuts. When physical composition was excluded, lysine and iron were higher and linoleic acid lower in older compared to younger animals, thus meat from older animals which is mostly consumed by people with severe iron-deficiency anaemia in the rural parts of South Africa, is adequate to meet this need. Lysine as one of the nine essential amino acids for adults, was higher in the C-age meat, contrary to belief that it is of inferior quality and can be recommended as part of a balanced diet. Palmitic acid (16:0) increased with age while Linoleic acid (18:2) decreased with age. Significant differences in fat content (subcutaneous and proximate), meat, moisture, various fatty acids (palmitic, stearic and oleic acids) and calcium were found between the different cuts. Hydroxyproline, glycine and some minerals discriminated the most between the different cuts within a carcass.