Post Mortem Changes in Muscle

Martinsen 0G, Grimnes S, Mirtaheri P. 2000. Non-invasive measurements of post mortem changes in dielectric properties of haddock muscle—A pilot study. / Food Eng 43,189-192. 

Tarr, H.L.A. (1966) Post-mortem changes in glycogen, nucleotides, sugar phosphates and sugars in fish muscles. A review. J. Food Sci. 31, 846-854. 

Table 12.10 gives an example of post mortem changes in rabbit Psoas major as related to concentrations of some of the more irrportant muscle tissue constituents. The data shown in Fig. 12.22 illustrate the post mortem decreases in pH, creatine phosphate and ATP in beef Longissimus dorsi and Psoas major muscles and err5>hasizes that the changes are dependent on the t)fpe of muscle. 

Fig. 12.23. The efl ect of temperature on post mortem changes in beef muscle.

The other enzymatic reactions found in fish seem to be common to all vertebrates. Study of these reactions has been mainly directed towards the biochemical changes occurring post-mortem in fish muscle, the so-called internal factors of fish spoilage which have involved investigations in glycolysis, lipolysis, and proteolysis. 

Trimethylamine oxide, (CH3)jN+0, an onium salt found in marine but never in fresh-water fishes. Rich sources are eephalo-pods and crustaceans, the muscle of the lobster containing about 0 3 per cent. The oxide is soluble, non-toxic and almost neutral, and is an important excretory form of nitrogen. Among the elasmobranchs it serves in the maintenance of fluid equilibrium, and is responsible for 20-25 per cent, of the total osmotic pressure of the blood. It is rapidly decomposed by post-mortem autolytic and bacterial changes, and the liberated trimethylamine, (CH3)jN, characterises the odour and taste of stale marine fish. 

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