title: Effect of heating rate on shortening, ultrastructure, and fracture behavior of prerigor beef muscle.
abstract: Rapidly heated prerigor beef is tender because of incompletely described myofibrillar disruption and tissue fracture. This study was designed to evaluate the effects of heating rate on heat-induced myofibrillar shortening, ultrastructural changes, and fracture behavior in prerigor triceps brachii muscle. Rapid heating (2°C/2 min) to 53°C caused (P < 0·05) more severe myofibrillar shortening in a shorter time and at higher muscle pH and temperature, less muscle weight loss, and shorter sarcomeres than slow heating (2°C/12 min) to 47 or 53°C. Rapid heating caused more extensive degradation of A and I bands, greater loss of the tridimensional pattern of myofibrils, more fragmentation and melting of myofibrils, widened intermyofibrillar spaces, and maximum separation of fiber bundles as compared to slow heating. Slow heating caused extensive shortening but not extensive degradation and disruption of myofibrils. Muscles slowly heated to 53°C sustained greater loss of structural integrity than those slowly heated to 47°C, but fracture behavior was similar. Separation and fracture occurred near the perimysial/endomysial junction in all heated samples, but the perimysium remained affixed to the endomysium at one side of the interface in many rapidly heated samples. Longitudinal fractures showed a granular endomysium and large numbers of supercontraction nodes alternating with areas of sarcolemmal membrane fragmentation and fiber tearing in rapidly heated samples. Alterations of myofibrillar ultrastructure and fiber structure, and separation of bundles, may account for enhanced tenderness of rapidly heated prerigor muscle.
authors: Purdue University, West Lafayette, Indiana 47907, USA.
authors: T J
authors: TJ
authors: Silva
authors: M W
authors: MW
authors: Orcutt
authors: J C
authors: JC
authors: Forrest
authors: C E
authors: CE
authors: Bracker
authors: M D
authors: MD
authors: Judge