Changes in rheological properties of grass carp fast skeletal myosin induced by seasonal acclimatization

To elucidate the effects of seasonal temperature acclimatization on thermal gelation of grass carp myosin, myosins from fish in different seasons were prepared and investigated for the changes in dynamic viscoelastic parameters including storage modulus (G'), loss modulus (G'') and damping factor (tan delta) upon heating. Myosins from fish in spring and summer had a temperature region of 38-44 degrees C for the first marked increase of G' higher than that of myosins from fish in autumn and winter (28-33 degrees C). The measurement temperature-dependent changes in dynamic viscoelastic parameters such as G'' and tan delta were also different among the four myosins. While gel formation was observed with the spring and summer myosins, apparently in two steps, three steps were found in the autumn myosin. Furthermore, the winter myosin exhibited more than three steps for gel formation. These differences in rheological properties among the four myosins were considered to be attributed to the differences in thermodynamic and structural properties of these myosins previously reported.