The effect of electrical stimulation on the water-holding, capacity and protein denaturation of two bovine muscles

The effect of low-voltage electrical stimulation on the water-holding capacity and protein denaturation of bovine longissimus thoracis and semimembranosus was studied in eight electrically stimulated (85 V, 14 Hz, 15 s; immediately after slaughter) and eight nonstimulated Friesian Holstein bull carcasses. At 24 h postmortem longissimus thoracis and semimembranosus were sampled for drip loss, thaw loss, filter paper wetness, myofibrillar water-holding capacity, protein content of drip, protein solubility, myofibrillar ATPase-activities, and bound phosphorylase. Electrical stimulation resulted in higher (P < .05) drip losses and filter paper wetness and lower (P < .05) myofibrillar water-holding capacity of semimembranous samples. The increased drip loss coincided with decreased (P < .05) sarcoplasmic protein solubility, decreased (P < .05) myofibrillar ATPase-activity, and decreased (P < .05) protein concentration of drip. In the longissimus thoracis, electrical stimulation resulted in a lower (P < .05) myofibrillar water-holding capacity. However, this was not reflected in higher drip losses. In this muscle, only a decreased (P < .05) sarcoplasmic protein solubility and increased (P < .05) amount of bound phosphorylase was observed. The results indicated that the negative effect of electrical stimulation on drip loss is possibly the result of myosin denaturation, which is determined by postmortem pH and temperature fall and thus varies by muscle studied. Sarcoplasmic protein denaturation seemed not to be involved in determining water-holding capacity.