Ultrastructure Of Stressed Bovine Muscle

Abstract

Measurements of a variety of physical properties of muscle tissue have been proposed as objective tests for meat tenderness. We have attempted to single out a specific physical factor, namely tensile stress, and to determine its effect on the ultrastructure of raw and cooked muscle tissue. Extension of this approach to the other physical factors involved in mastication will hopefully establish the structural factors important to meat tenderness.The bovine semitendenosus muscle (eye round) was obtained either commercially or excised from a carcass aged under controlled conditions for 10 days. Small strips (¼” x ¼” x 1-½”), raw and cooked at 90°C, were subjected to tensile stress and then fixed in glutaraldehyde. A motorized minitensile stage (Fig. 1), designed to be small enough to operate within the SEM, stressed the muscle samples while viewed by a stereomicroscope and simultaneously monitored with a closed circuit TV system. Identical areas of samples subjected to tensile stress could be observed in both the light and scanning electron microscopes (Fig. 2).