Viscoelasticity of carp actomyosin solution during heating.

Abstract

The steady and dynamic shear rate behaviors of carp actomyosin solution were measured during incubation at 40°C. The maximum steady shear viscosity was observed around 35 min, while the maximum dynamic rigidity was observed around 2h. The hysteresis loop area increased for 2h, and thereafter it remained almost unchanged till 6h where the dynamic rigidity decreased. Therefore we deduce that during the incubation, the network structure would develop also in the carp actomyosin solution as in the hen or rabbit myosin solution, but the network structure of carp actomyosin solution would be so weak as to be broken down even during the repeated measurements of dynamic behaviors. The actomyosin solution at pH 5.8 exhibited the lowest viscoelasticity. The solution at pH 6.8 exhibited the highest dynamic rigidity. The solution at pH 7.8 exhibited the highest stress in the shear rate scan measurement. These results were explained by the fact that the actomyosin solution at pH 5.8 existed near the isoelectric point, and the network structure at pH 6.8 would be different from the network structure at pH 8.8. In the temperature scanning experiment the dynamic rigidity began to increase around 40°C the maximum was observed around 61°C, The peak value around 61°C was high at pH 5.8 and pH 6.8, and low at pH 7.8.