Studies in Meat Tenderness. 7. Changes in the Fine Structure of Meat During Aging

SUMMARY— During the aging of fiber pieces prepared from bovine sternomandibularis muscles, a loss of adhesion occurs between adjacent myofibrils. This is evidenced by increased readiness of fiber pieces to distintegrate into individual myofibrils during a period of standard disruption. Alterations also appear within the myofibrils themselves in the regions of the Z lines, sometimes leading to the apparent dissolution of this structure. Ethylenediamine tetraacetate present in the suspensions during storage not only prevents these changes, but also preserves the refractory character of the fiber pieces. Meat aging is considered therefore to be due to disruption and possible dissolution of Z-line material, leading to a weakening of inter-myofibrillar linkages probably located at the junctions of adjacent Z lines, and to loss of tensile strength of the myofibrils themselves.