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.