Post-mortem changes of horse mackerel myofibrillar proteins and sarcoplasmic protein were studied by means of solubility, viscosity and salting-out curves. Horse mackerel used was killed under narcosis and stored in crushed ice. Ordinary muscle samples taken from three to five whole bodies were combined and used for the preparation of extracts.
The solubility of 0.6M KC1-soluble proteins and myosins was greater at rigor stage than at pre-α post-rigor stage (Fig. 1), as has been found in other fishes¹⁾. However, the amount of sarcoplasmic protein extractable with 0.005M KC1 was found to decrease during storage.
It has been suggested by one of the authors¹⁾ that intrinsic viscosity of actomyosin of many pelagic fishes decreased to 0.5-0.2 after death, but in the case of horse mackerel the value decreased little by little (Fig. 2).
Salting-out curves of myosins show that at any stage peaks of actomyosin or myosin and tropomyosin fractions appeared, while only at rigor and post-rigor stages the actin peak did (Fig. 4).