Electrical stimulation - when more is less

This study was conducted to determine whether electrical stimulation per se can be omitted when other electrical inputs to beef carcasses (stunning and immobilisation) are used. In addition, we investigated which sample preparation method at 1 day post mortem (p.m.), cooked fresh, frozen, or after thawing, had the best predictive value for shear force after ageing of the muscle. Beef carcasses were electrically immobilized (75 V, 15 Hz) before and during exsanguination for 20 or 80 s and meat quality characteristics of the longissimus were determined at 1 and 7 days post mortem. Muscles from carcasses receiving the higher electrical input were similar in tenderness at 1 day p.m., but tougher at 7 days p.m. This result could be explained by the effect of muscle shortening and post mortem proteolysis on tenderness. These results indicate that even low electrical input during immobilization can adequately stimulate carcasses and avoid cold shortening. Freezing samples resulted in a considerable improvement in tenderness and cooking samples from the frozen state had the highest predictive value for tenderness after ageing. In a second experiment it was determined that freezing and thawing did not result in appreciable differences in cooking loss or proteolysis. The tenderising effect of freezing may be explained by tissue damage due to ice formation. (C) 2000 Elsevier Science Ltd. All rights reserved.