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

Abstract

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.

Subcellular events associated with the development and release of isometric tension in post-mortem bovine, rabbit and porcine skeletal muscle

“…The fragmentation of myofibrils prepared from post-mortem muscle has been observed previously (Davey and Gilbert, 1969;Henderson, 1968;Stromer and Goll, 1967a;Takahashi et al, 1567) and is generally attributed to weakening at the Z-line. The pre servation effect of added EDTA or EGTA on myofibrillar structure is quite remarkable since Henderson (1968) has shown that myofibrils prepared from rabbit muscle stored in air for 4 hours at 37° are fragmented and have no Z-lines.…”

“…This fragmentation of post-mortem myofibrils occurs primarily at the Z-line, which suggests that post-mortem myofibrils are weakened at this point so that they break or rupture during the homogenization pro cedure used in myofibril preparation. Recently, Davey and Gilbert (1969) have observed that Z-line in post-mortem bovine muscle may be removed from the myofibril altogether and that adjacent myofibrils appear to lose their affinity for each other.…”

A Judgment on Postmortem Aging inLongissimus DorsiBased on a Peptide Substrate Library

“…The addition of EDTA decreased the fluorescence intensity against Ac-X 1 -MCA and Ac-Ala-Phe-MCA. On the basis on Davey's report, 20) which suggests that EDTA inhibits the degradation of Z lines by chelating calcium, it was hypothesized that the reaction of these substrates might involve calpains, a calcium-dependent protease. It is known that cathepsin B reacts specifically with the substrate Z-Arg-Arg-MCA or Z-Phe-Arg-MCA, 21) and that cathepsin L reacts specifically with the substrate Z-Phe-Arg-MCA.…”

Studies on Jellied Meat of Tuna-II

“…The second is a weakening of myofibrils themselves, resulting in a breaking in I band region. According to the recent investigations on so called meat aging, [8][9] this is a commonly encountered phenomenon. However, the change which occurs during the jellification of tuna meat must be more drastic than that occurring during meat aging, and likely associated with a disintegration of connective tissue or sarcolemma.…”