The myofibrils were successfully prepared from frozen surimi of Antarctic krill by the ordinary method of KATOH
et al., when the operations were performed at 0-4°C throughout and finished within an hour.
The specific Ca-ATPase activity of this myofibrils preparation rapidly decreased even during icedstorage. Such inactivation of Ca-ATPase was found to be effectively prevented by adding 1.5M monosodium glutamate (or sorbitol) to the preparation.
The maximal activity of myofibrillar Ca-ATPase was observed at about 17°C for krill. It was a low temperature compared with those observed for fishes and whale; 30°C for Alaska pollack, 36°C for sardine, and 47°C for little piked whale.
From the first order inactivation rate constants (
KD) of myofibrillar Ca-ATPase at various tempera-tures, linear ARRHENIUS plots were illustrated for krill, grenadier, Alaska pollack, sardine, and little piked whale in the temperature ranges of 5-25°C, 10-30°C, 15-35°C, 25-40°C, and 36-50°C, respectively.
The
KD values of myofibrillar Ca-ATPase of krill in the presence of sorbitol at various tempera-tures were also measured. The linear plots of log
KD versus 1/T, supported that the thermo-stabilities of krill myofibrils with 1.5, 2.0, and 3.0M t sorbitol were comparable to those of grenadier, Alaska pollack, and Pacific mackerel myofibrils, respectively.
The significance of this result was discussed in relation to the rapid deterioration of Antarctic krill meat after the catch.
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