EFFECT OF HIGH-PRESSURE TREATMENT ON THE ULTRASTRUCTURE AND MYOFIBRILLAR PROTEIN OF BEEF SKELETAL-MUSCLE

High hydrostatic pressures of 100 MPa to 300 MPa were applied to beef post-rigor muscle to investigate the efficiency of pressurization as a meat tenderizer. The fragmentation of myofibrils increased with increasing pressure applied to the muscle, and the degree of fragmentation reached to its maximal level after briefly exposing (5 min) post-rigor muscle to the highest pressure (300 MPa). Electron microscopic studies of the pressurized muscle revealed that marked rupture of I-band and loss of M-line materials had progressed in the myofibrils with increasing applied pressure. However, degradation of the Z-line in myofibrils that can be observed naturally in conditioned muscle was not apparent in the pressurized muscle. There was no significant difference in the electrophoretic pattern of myofibrillar protein among the control and pressurized muscle samples in spite of the marked change of ultrastructure. From the results, it is suggested that the application of a high hydrostatic pressure to post-rigor muscle causes tenderization of the meat in a different manner from that of conditioning.