かまぼこの足について-XIII

加熱による魚肉ゾルの粘度変化

抄録

In this study, we have investigated the influence of heating on the viscosity of a fish muscle sol. Sols were prepared by extracting lizard fish muscle with 10vol. of 0.6M NaCl (pH 6.8) overnight at a temperature between 3° and 5°C. All the vicosity measurements were carried out at 5° ± 0.5°C by using a Brooksfield type viscometer after heating at different temperatures for various periods.
Changes in viscosity values during heating occurred in two steps; a remarkable increase at a temperature range between 30° and 40°C, and a sudden fall accompanied by a coagulation of proteins and also a release of water between 40° and 50°C, which temperature was known as the coagulation temperature of myosin-B (Fig. 1). However, the rise and fall in the viscosity were dependent on both temperature and period of heating. After prolonged heating, the viscosity-increase were obsevued even at a lower temperature (e. g. 20°C), and the gradual decrease occurred below 40°C. (e. g. 35°C.) after the stage of the viscosity-increase (Fig. 2). The occurrence of such a viscosity-increase was found to be independent of the pH value of sol (Fig. 4), but the rate of the increase was a function of the consistency of the sol (Fig. 3).
The first step, an increase in the viscosity of the fish muscle sols during heating, may be interpreted in terms of the unfolding and the hydration of actomyosin chains, and the second step, fall in the viscosity, may probably be due to the formation of cross-linkages between the unfolded chains.