Studies On Variations Of Microscopic Structure Of Myofibrils And Crude Activity Of Calpains Of Bovine And Mutton Skeletal Muscle Under Hydrostatic High-pressure Processing

The objectives of this study were to examine the effects of hydrostatic high-pressure (HHP) treatment on microscopic structure of myofibrils and crude activity of calpains of bovine and mutton skeletal muscle. The mechanism that HHP can increase the tenderness of bovine and mutton muscle was indicated. The muscle of bovine and mutton varied a lot after HHP treatment : colour faded, extension decreased and mortem flavour emerged. Under the condition of 700MPa pressure level , 25 癈 and 20 min of HHP treatment ,the remarkable variation can be seen in microscopic structure of myofibrils of bovine and mutton muscle . Sarcomere occured obvious changes. The contraction rate of bovine and mutton sarcomere was 34.8% and 22.2% respectively. Meanwhile, Z-lines broke, M- lines degradated and I band darkened. When the pressure level ranged from 1 OOMPa to 400MPa, the crude activity of calpain of mutton muscle decreased gradually with pressure increasing. At the level of SOOMPa , the calpain crude activity rose again. At the level of 400MPa ,the calpain crude activity almost inactivated. When calpain was preserved under the condition of 4癈 its crude activity decreased as keeping time prolonging. Whe"n the emzyme was kept for a month, its activity remained 1.5% of the one that was extracted initially When the pressure level ranged from 1 OOMPa to 400MPa ,with the pressure increasing ,pH value increased and shear force decreased remarkablely. It indicated that HHP treatment can promote meat aging and increase meat tenderness. The result of this study will provide a reliable theoretical base to the development of meat tenderization technolodgy.And it has a profound meaning for high-pressure meat product.