EFFECT OF ELECTRICAL-STIMULATION ON THE WATER-HOLDING CAPACITY AND PROTEIN DENATURATION OF 2 BOVINE MUSCLES

The effect of low-voltage electrical stimulation on the water-holding capacity and protein denaturation of bovine longissimus thoracis and s emi-membranosus was studied in eight electrically stimulated (85 V, 14 Hz, 15 s; immediately after slaughter) and eight nonstimulated Friesi an Holstein bull carcasses. At 24 h postmortem longissimus thoracis an d 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 phospho rylase. Electrical stimulation resulted in higher (P <.05) drip losses and filter paper wetness and lower (P <.05) myofibrillar water-holdin g capacity of semi-membranosus samples. The increased drip loss coinci ded 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 stimul ation resulted in a lower (P <.05) myofibrillar water-holding capacity . However, this was not reflected in higher drip losses. In this muscl e, only a decreased (P <.05) sarcoplasmic protein solubility and incre ased (P <.05) amount of bound phosphorylase was observed. The results indicated that the negative effect of electrical stimulation on drip l oss is possibly the result of myosin denaturation, which is determined by postmortem pH and temperature fall and thus varies by muscle studi ed. Sarcoplasmic protein denaturation seemed not to be involved in det ermining water-holding capacity.