Abstract
The dynamic viscoelastic properties of cooked rice grains were investigated by small shear deformation under compression with 50% deformation. The linear range of viscoelasticity for cooked rice grains was estimated to be at less than 0.4% strain, when the compressed grain was assumed to be a cylinder. The frequency dependency of dynamic viscoelasticity for cooked rice grains indicated that the grains were viscoelastic solids having multiple relaxation modes. The relaxation spectrum of cooked rice grains indicated that the grains had the two relaxation systems : short- and long-time relaxation. The relaxation time in the short time relaxation mode for old cooked rice grains was longer than that for new grains. It was strongly suggested that the low molecular weight components of old rice became higher molecular weight components to a greater degree than in new rice.
