Study on Creep Properties of Japonica Cooked Rice and Its Relationship with Rice Chemical Compositions and Sensory Evaluation

Abstract

Creep properties of four varieties japonica cooked rice were tested using a dynamic mechanical analyzer (DMA Q800). The creep curve was described by Burgers model. The creep process of japonica cooked rice mainly consisted of retarded elastic deformation, ?R and viscous flow deformation, ?V, and negligible instantaneous elastic deformation, ?E. The retarded elastic modulus, ?2, relaxation time, ?, and the viscosity coefficient, ?1, of the cooked rice according to the Burger model were estimated through nonlinear regression. The effect of the chemical compositions on the rheological parameters based on creep behavior of cooked rice was assessed. Correlation analysis indicated that the retarded elastic modulus, ?2, had positive correlations with protein (r = 0.952, P = 0.048). The relaxation time, ?, had negative correlation with protein content (r = -0.909, P = 0.091). The viscosity coefficient, ?1, was negatively correlated to amylose (r = -0.915, P = 0.085). The analysis between creep parameters and sensory evaluation showed that the viscosity coefficient, ?1, positively correlated to stickiness and total evaluation of cooked rice. So it can be used to evaluate the eating quality of cooked rice.