1. Department of Food Science, University of Massachusetts, Amherst, Massachusetts 01003; National Center for Agricultural Utilization Research, Agricultural Research Service, U.S. Department of Agriculture, 1815 North University Street, Peoria, Illinois 61604; Meat Science and Muscle Biology Laboratory, University of WisconsinMadison, 1805 Linden Drive West, Madison, Wisconsin 53706; and Department of Biochemistry, Memorial University of Newfoundland, St. John's, Newfoundland A1B 3X9, Canada