An investigation of ultimate pH in the muscles of commercial beef carcasses.

Ultimate pH values were recorded in the carcasses of steers and heifers at a beef slaughtering plant over a period of 3 years. The incidence of carcasses with a pH(u) ≥ 6·0 in the LD-a value usually associated with 'dark-cutting' in beef-was 3·2%. A pronounced seasonal effect was observed with the incidence rising from 1·2% for the period February to August to 5·2% for the period September to January, inclusive. An examination of thirteen muscles showed that increases in pH(u) above normal values occurred most frequently in the LD and four large muscles of the hindquarter and were much less frequently observed in the eight other hind- and forequarter muscles examined. In the carcasses of young bulls, also slaughtered under commercial conditions, high pH(u) values were predominantly associated with the same muscles as in steers and heifers. However, when experimental cattle were given adrenaline to induced high pH(u) values, this treatment resulted in a general increase in pH(u) in all the muscles examined. The different pattern of pH(u) elevation in the adrenaline-treated and commercial carcasses suggests different physiological mechanisms in the two cases.