The connective tissues of fish III. the effect of pH on gaping in cod entering rigor mortis at different temperatures

Abstract

When cod enter rigor mortis and are then filleted, the amount of gaping seen between the muscle segments depends on the previous body temperature, increasing progressively with warmth. In the present work it was noticed that in any batch of fish a few pairs of fillets showed little gaping even at relatively high temperatures (22-25 "C). The factor responsible was identified as the pH of the muscle, a low pH leading to much gaping and vice versa. At a given temperature, the gaping increased with time, and subsequent freezing increased it further. The practical implications of these findings are discussed.

The connective tissues of fish.

“…The phenomenon was found by Love & Haq (1970) to be influenced also by pH, but at 25°C almost all the cod gaped maximally, with pH playing only a minor modifying role.…”

“…3 show that trout gape maximally after passing through rigor mortis at or above 35"C, whereas cod gape maximally above about 25°C (Love & Haq, 1970).…”

Effect of handling treatment on fillet yields and quality of tropical fish

“…The extent of shrinkage is dependent upon the temperature of the fish in the same way that gaping is affected. The muscle pH also affects gaping (Love & Haq, 1970): as the pH decreases, gaping increases. Thus the pre-rigor fillets in this study suffered the least gaping since they underwent rigor off the bone.…”