On the Gelation of Fish Actomyosin by Gamma Irradiation

Abstract

To obtain the basic aspect on the qualitative change of fish flesh in radiation preservation, effects of gamma irradiation on some properties of fish actomyosin were investigated. As a remarkable change from sol to gel of carp actomyosin solution during irradiation was observed, the gel formation and its specificity under various conditions were described in this paper.
The results obtained are as follows:
1) The gelation was observed organoleptically in a higher concentration of actomyosin than 0.3 mg protein nitrogen/ml and above the irradiation dose of 8× 10⁴R. (Table 1)
2) The concentration of KCl in actomyosin solution had a close relation to the gel rigidity. The highest rigidity was observed at the KCl concentration of 0.6M. (Table 2) Thus, this fact may bring an important influence on the quality of such a salt-treated flesh during irradiation.
3) The suppressing effect of dissolved oxygen on the gelation of irradiated actomyosin was observed, while N₂, H₂ and He gasses accelerated the gelation respectively. (Table 3)
4) Added oxidants such as KBrO₃ and KI0₃ accelerated to gelify, and the antioxidant, sodium D-isoascorbate restrained fairly the accelerative effect of KBrO₃ during irradiation. (Tables 4 and 6)
5) Dissolved oxygen showed also a synergistic enhancement on the gelation of irradiated actomyosin when KBrO₃ was added to the actomyosin solution. (Table 5) From the above results, it is supposed that the mechanism of gel formation by ionization and oxidation by molecular oxygen differs primarily from that of various oxidants.
6) From the differences of the, protein solubility in super-natant centrifuged, it was illustrated that a higher macromolecule of actomyosin was formed during irradiation. (Figs. 1 and 2)
7) The roles of sulfhydryl groups on the gel formation was suggested from the results of polarographic observation of protein waves. (Fig. 3)