EFFECT OF TENSILE STRESS ON THE ULTRASTRUCTURE OF BOVINE MUSCLE

The changes in ultrastructure of bovine semitendinosus, both raw and heated (90°C) and subjected to tensile stress, were determined by scanning electron microscopy. Stress parallel to the fiber axis resulted in the initial rupture of the muscle fiberendomysium sheath. Perpendicular stress caused initial rupture at the endomysium-perimysium junction with the muscle fibers remaining undisturbed. Similar observations were made on the muscle tissue heated to 90°C and subjected to tensile stress. Heating to 90°C does not alter completely the fibrous nature of the perimysium connective tissue. Some native type collagen fibrils were observed, even after the severe heat treatment. The effect of applied stress on components of the muscle tissue is an important consideration in the development of a more reliable test method for evaluation of meat tenderness.