Effect of Mixed Air Bubbles on Mechanical Properties of Kamaboko and Hanpen (Fish Jelly Products)

Abstract

In order to clarify the effect of fine air bubbles in mochi cake on the large temperature dependence of elastic modulus of the cake, complex modulus, apparent specific volume and distribution of proes in Kamaboko and Hanpen which were quite different in air content to each other were measured.
Temperature dependence of the dynamic modulus of Hanpen showed a similar decline to that of the relaxation modulus of mochi cake. The modulus of Kamaboko, however, did not show such a decline above 50°C, on the contrary, a steady or upward trend was observed. Increase in the elasticity of the protein gel in Kamaboko by temperature was considered to due to be the natural character of the gel, or hardening of the structure resulted from progressive coagulation of the protein by reheating.
Both the apparent specific volume and the rate of volume increase of Hanpen were larger by five-fold than those of Kamaboko at room temperature. Differential of specific volume, i.e., coefficient of cubical expansio vs. temperature curve, showed a transition point that suggested some changes in the gel structure.
Size and distribution of pores measured by microscope agreed with the result by determining specific volume.