STUDIES ON MUSCLE OF AQUATIC ANIMALS-XXXIX

PROTEASE IN FISH MUSCLE

Abstract

Fish muscle paste turns into a tough and elastic gel when kept at elevated temperatures. It has been observed¹⁾ that the muscle paste shows a higher gel strength either at 30°-40°C or above 70°C, while a lower one at about 60°C. Some proteolytic enzyme were assumed to be connected with this phenomenon, the lowering of gel strength at about 60°C.
As seen in Fig. 1, addition of trypsin clearly depressed the gel formation of muscle paste. at all the temperatures, especially above 50°C. This was also true for the crude preparation of proteolytic enzyme from fish muscle. The optimum pH and temperature of this enzyme preparation were found at pH 7-8 at 60°C and 60°C at pH 8, respectively, in the fish species examined (Figs. 2 and 3). Temperature quotient, Q₁₀, was calculated to be 1.6 between 40° and 50°C, whereas as high as 7.6 between 50° and 60°C (Fig. 4).
These results may suggest that the lower gel strength observed at about 60°C is partly due to the action of proteolytic enzymes originally present in fish muscle paste.