Fat content and fatty acid composition of South African Wagyu beef

Abstract

The number of Wagyu breeders is growing and the availability of Wagyu beef has increased in South Africa over the past few years. Virtually no research has been done on local Wagyu beef. Diets, feeding and cattle-rearing strategies of Wagyu cattle in South Africa differ from those in Japan. Most Wagyu’s for slaughter are of the F1 generation. This may affect the fat content and fatty acid (FA) composition of South African Wagyu beef. The fat content and the FA composition are influenced by many factors. Wagyu cattle are known to be genetically predisposed to produce vast amounts of marbling or intramuscular fat in the beef cuts. A common misconception among consumers is that all fat in red meat is saturated and will have a negative effect on health, especially non-communicable diseases. On the contrary, red meat has many benefits for human health, and is a source of essential FA, of fat-soluble vitamins and minerals, as well as of protein and energy. In this study South African Wagyu beef and beef from composite feedlot cattle were compared in respect of fat content and FA composition. Samples were collected from different fat depots in carcasses of 13 randomly selected Wagyu and 13 composite feedlot cattle at a commercial abattoir. Intramuscular (IM), subcutaneous fat (SCF) and perirenal fat (PRF) samples were collected from each carcass. All samples were collected on the left side of each carcass. FA analysis was done on 78 samples to determine the FA composition of each anatomical location for both Wagyu and typical composite feedlot cattle. Ether extracts were done on all the IM Wagyu samples to determine the actual fat percentage and to compare that to the estimated fat percentage given by the marbling score. One would assume that the higher amount of fat in Wagyu beef would be unhealthy because it is the same FA in the same ratio as in beef from composite feedlot cattle in South Africa. The results of this study show that there is a difference in the FA composition between Wagyu and composite feedlot cattle. The same FAs were detected in both; however the amount of each FA differs. More IMF is found in Wagyu than in composite feedlot cattle. The ratio of the main FA groups was also calculated and compared. The ratio of n-6/n-3 is significantly lower in Wagyu beef than in composite beef, which is more favourable when comparing this ratio to the recommended daily intake. The measures used to determine marbling score is the Australian marbling score and the MIJ camera marbling score. For each marbling score these measurements gave an estimated fat percentage. These estimates were compared to the actual fat percentage. These two measurements were significantly correlated. The MIJ camera marbling scores were better correlated to the actual fat percentages.