食品のレオロジー

特にかまぼこについて

抄録

Kamaboko is a heat-coagulated fish paste containing some salt, sugar, starch and flavor, and is one of the favorites of Japanese people. The rupture properties of Kamaboko, such as the breaking strength and the breaking elongation, are considered as one of the most important factors in evaluating the commercial quality of this product. The quality of Kamaboko has been estimated in terms of pastelike compactness which in Japanese is known as“Ashi”. This in reality embodies rheological properties. The results of ranking Kamaboko on market by“Ashi”or compactness have shown that this is closely related to its being hard, but not so much so as to be tough, and also to its being fit for chewing chear cut. The organoleptic scores for the Kamaboko, how hard it is, were found to be related to the gel strength, the elastic energy stored in the specimen before breaking. On the contrary, the evaluation of Kamaboko being fit for chewing clear cut has not yet been established.
The data for the creep in a simple shear, the stress relaxation in extension and the damped free oscillation in torsion of commercial Kamaboko have shown that this is considered to be a thermorheologically simple material and a slightly crosslinked rubbery material which exhibits no viscous flow.
The results of stress relaxation of fresh fish meat paste were expressed as:
f/f₁₀=a-klogt,
where f is the stress at time t, f₁₀ the value of f at t=10sec, a and k the constants, and t the time, respectively. The stress relaxation measurements were made for the meat paste heated at various temperatures and heating times. It was found that the values of f₁₀ increase and those of k decrease with increase of temperature and heating time.
The measurements of the viscosity of the fish muscle extracts were made at various velocity gradients. The relation between the viscosity, η, and the velocity gradient, D, followed the de Waele-Ostwald law:
η=KDⁿ
where K and n are constants. Moreover, the viscosity, η, of fish muscle extracts at constant velocity gradient was found to be related to the concentration C as:
η_D=2=kC^m.