Effect of ageing under tropical conditions on the eating qualities of beef

Beef is a major source of animal protein in Ghana but most of it comes from old and poorly conditioned animals, which produce tough meat with poor eating qualities. The eating quality of tough beef can, however, be improved by methods of tenderizing such as ageing, electrical stimulation and application of enzymes. The purpose of this work was to study the effect of ageing under tropical conditions with high ambient/room temperatures (average 350C) on the eating qualities of beef. Fresh beef longissmus dorsi muscle from a matured Sanga bull was used. The muscle was cut into four equal steaks measuring 10 cm long with an average weight of 373g in duplicates and subjected to ageing treatments for 5, 10 and 15 days at a temperature of 20C ± 20C. The control samples were frozen throughout the experiment. After each period of ageing, the samples were immediately frozen to halt further ageing process. Swabs were taken on the samples for microbiological analysis before and after each ageing period to determine the microbial quality of the steak after ageing. Fourteen untrained sensory panelists assessed the eating qualities: tenderness, beef flavour, juiciness and abnormal flavour of the samples. The ageing process resulted in highly significant improvements in tenderness and juiciness of the beef steak. Ageing for 10 to 15 days produced very tender steaks whilst the control steaks remained very tough (P< 0.001). The beef steaks became more juicy with increasing time of ageing and beef flavour intensity was significantly (P< 0.01) enhanced from day 5 to becoming strong by the day 15, whilst abnormal flavour intensity was not affected by the ageing process. On acceptability, majority of the panelists preferred the steaks aged for 10 or 15 days as the best meat. The ageing process did not have any detrimental effect on drip loss and microbial quality of the beef steaks. The problem of very tough beef from old animals in tropical countries can be minimized considerably through the practice of ageing.