Studies on the “Arai” Phenomenon (the Muscle Contration Caused by Perfusing Water)-IV

It is commonly believed that fish muscle rich in muscle pigment as like mackerel and sardine decays more rapidly than those of white meat fish such as carp or red-snapper. But, only few informations are available for their difference. In this connection, the present study is scheduled to find out, if possible, a difference of rigor mortis between the muscles of red and white meat fish. Mackerel was used as a model of red meat fish and carp and red-snapper as white one. Sample fish were treated in two ways; one was to cut off head immediately after catch and another was to put into death after heavy struggling. And the amount of Δ 7P-P, glycogen, SH group and muscle contraction caused by perfusing water for each sample were determined and results were shown in Figs. 1-5. Difference in the changes of these compounds due to the variety of fish was not significantly observed, but the struggling of the fish till the time of death appeared to give remarkable effect on biochemical changes in the muscle. Therefore, the greater part of the freshness of commercial fish will depend on fishing method whether it involves the struggling or not at the time of catch. If the amount of A. T. P., glycogen and pH value could be maintained in high level when fish were killed on board, the rigor-mortis might proceed similarly in red and white meat fish.