MECHANICAL-PROPERTIES OF FOODS NEAR SOL-GEL TRANSITION POINT .2. CONCENTRATION-DEPENDENCE OF MECHANICAL-PROPERTIES OF GELATIN NEAR THE SOL-GEL TRANSITION POINT

The concentration dependence of mechanical properties for gelatin near the sol-gel transition point was analyzed by the scaling law derived from the percolation theory, and compared with the results previously obtained for polyacrylamide. The critical concentration at the sol-gel transition point, phi(g), was estimated from the concentration (phi) vs. the reciprocal of viscosity (eta) plots by extrapolating 1/eta to zero. The critical exponent for sol viscosity, s, was estimated from the slope of a log(phi(g)-phi) vs. log eta plot. The critical exponent s was about 1.1, being larger than the value predicted by the percolation theory assuming the superconductor model. The critical exponent for gel elasticity, t, was estimated from the slope of a log(phi - phi(g)) vs. log G' plot, where G' is the dynamic shear modulus at a frequency of 2 Hz. The critical exponent t was about 2, being similar to the value predicted by the percolation theory.