Post‐Mortem Changes in Chilled and Frozen Muscle

Abstract

SUMMARY The conception of Huxley concerning the structural basis of muscular contraction is universally accepted. It shows a close correlation between ATP and the fibrillar proteins, also existing during the first phase of the post‐mortem changes. Rigor development has been followed in whole fish and isolated beef muscles by measuring the torsion elasticity. Often there are great individual deviations in rigor development within a single species. Generally, at corresponding temperatures, rigor development lasts longer in mirror carp than in the gastrocnemius of beef; rosefish needs a longer time to reach maximum rigor than cod. Evidently, the rapid phase of ATP breakdown and increasing rigidity of muscles is initiated by inactivation of the Marsh‐Bendall factor in the post‐mortem period. Normally, contraction occurs when ATP is added to fiber fragments of aged meat. This implies that the aetomyosin complex formed during rigor development becomes dissociated, or at least may become dissociated easily, in aged meat, and that tenderness changes in the aging period are correlated to this process. ATP breakdown in fish muscle is highly activated by freezing and thawing (“biochemischer Verletzungseffekt”) and seems to be caused by inactivation of the relaxing factor. Fish (whole fish or fillets) frozen under normal commercial conditions immediately after death show an insignificant degree of thaw contracture. In cod and rosefish no significant difference has been found in the extractability of the actomyosin fraction, if the time passing between death and freezing was considered. In frozen muscle tissue stored below ‐18°C, ATPase activity and contractability decrease very slowly. This shows that the actin and myosin filaments are not subject to great structural changes by freezing and thawing. In the freezer‐burn area of muscle tissue the structure proteins lose the ability to contract on ATP addition more and more with increasing storage time; finally, even the plasticizing effect of ATP on the fibrillar proteins disappears, the fibrils scarcely change their original orientation.

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

“…Goll attempts to distinguish his proposed weakening of the actin-myosin interaction from earlier theories that sug gested that the actin-myosin interaction was completely dissociated during the resolution of rigor mortis (Partman, 1963;Weinberg and Rose, 1960;wierbicki ^ , 1954). However, Wierbicki et (1956) could find no evidence to support their earlier proposal that the actin-myosin interaction was completely dissociated during the resolution of rigor mortis.…”

THE EFFECT OF ELECTRICAL STIMULATION ON THE RATE OF POST‐MORTEM GLYCOLYSIS IN SOME BOVINE MUSCLES1

“…Marsh (1954) demonstrated that the rate of pH fall was progressively more rapid in bovine longis-9 simus dorsi as the ambient temperature was raised from 7 to 43°C. Early investigators realized that increased temperature caused an increased rate of post-mortem glycolysis, which results in a shorter interval between death and the onset of rigor, and in a marked increase in shortening of the muscle during rigor at the higher temperature (Bate- Smith and Bendall, 1949;Partmann, 1963). Both of these events have important implications to be discussed later in relation to delayed chill or "hot" processing.…”

Freezing skeletal muscle tissue does not affect its decomposition in soil: Evidence from temporal changes in tissue mass, microbial activity and soil chemistry based on excised samples

“…transfer between cells leading to inhibition of chemical reactions [2]. The damage caused by freezing skeletal muscle tissue (SMT) is not only morphologically destructive but it also leads to the denaturing of protein by dehydration and an incomplete reabsorption of water after thawing [2].…”

“…The damage caused by freezing skeletal muscle tissue (SMT) is not only morphologically destructive but it also leads to the denaturing of protein by dehydration and an incomplete reabsorption of water after thawing [2]. This can lead to water loss which depletes SMT of materials such as crystalloids, proteins, pigments and other breakdown products [3,4].…”