The basal toughness of unaged lamb.

Identification of the commencement of aging in relation to the rigor process was determined on lamb loin muscles by injecting a zinc-TRIS solution, which inhibits meat aging, into the muscle over the period when the pH was falling. Aging was evaluated by measuring the tenderness of cooked meat samples using a MIRINZ tenderometer. When zinc was injected into muscle above pH 6·5, the sarcomeres shortened and the cooked meat had an average shear force of 19 kgF (shear force is the force required to shear through at 1 cm cross-section sample). When sinc was injected into the muscle at pH values below 6·5 the sarcomeres did not shorten, and down to the ultimate pH, the shear force remained at approximately 15 kfF. Aging did not take place pre-rigor. The same relationships occurred for electrically stimulated muscle. The data indicate that the basal shear-force value of lamb loin prior to aging, i.e. the basal toughness level, is 15 kgF.