Effect of post-mortem ageing, method of heating and reheating on collagen solubility, shear force and texture parameters of bovine muscles.

Abstract

The muscles semitendinosus (ST) andpsoas major (PM) were removed from young bull carcasses 24 h after slaughter and stored at 4°C. On the 1 st , 6 th , and 12 th day of post-mortem ageing the chemical composition (moisture, fat, protein) and contents of total and soluble collagen were estimated. The muscle steaks were boiled at 100°C, roasted at 170°C or fried in vegetable oil at 160°C to the internal temperature of 75°C in each case. The heated muscles were stored at 4°C for 6 days and reheated in the same heating environment to the internal temperature of 60°C. In heated and reheated muscles determinations of total and soluble collagen, WB shear force measurements and texture profile analysis (TPA) were conducted. The raw PM muscle contained two times less intramuscular collagen than ST muscle. The solubility of PM muscle collagen was higher than the solubility of ST muscle collagen. During post-mortem ageing the collagen solubility of both muscles increased. In the boiled muscles the level of soluble collagen was lower than in the roasted or fried ones. During post-mortem ageing the WB shear force, TPA hardness and TPA chewiness values of both muscles decreased. At the same time of post-mortem ageing, WB shear force values were the highest for boiled, middle for roasted and the lowest for fried muscles. The roasted muscles had the highest and fried ones the lowest values of TPA hardness, whereas values of TPA chewiness were similar, independently of the heating method used. The reheating of muscles after 6 days of cold storage had no effect on the WB shear force, although their TPA hardness and TPA chewiness values increased.