Submitted to: International Journal of Food Engineering
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/20/2009
Publication Date: 5/1/2009
Citation: Chang, S., Li, D., Lan, Y., Ozkan, N., Chen, X., Mao, Z. 2009. Study on creep properties of Japonica cooked rice and its relationship with rice chemical compositions and sensory evaluation. International Journal of Food Engineering. 5(3):Article 10. Interpretive Summary: Rice is a major staple food in many countries, but very few studies have investigated the viscoelastic properties of cooked rice. The deformation characteristics of four varieties of cooked japonica rice were tested and the chemical composition of the rice, protein and amylose content were measured. The relationship between deformation parameters, chemical composition, and sensory evaluation was analyzed to establish guidelines for the selection of a suitable variety for cooked rice and instrumental evaluation of eating quality. The viscosity coefficient was found to be negatively correlated with hardness of cooked rice, but positively correlated with stickiness and total evaluation of cooked rice. Thus, the viscosity coefficient can be used to evaluate the eating quality of cooked rice.
Technical Abstract: Creep properties of four varieties japonica cooked rice were tested using a Dynamic Mechanical Analyser (DMA Q800). The creep curve was described by Burgers model. The creep process of japonica cooked rice mainly consisted of retarded elastic deformation, epsilonR and viscous flow deformation, epsilonV, and negligible instantaneous elastic deformation, epsilonE. The retarded elastic modulus, '2, relaxation time, tau, and the viscosity coefficient, eta1, 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, tau, had negative correlation with protein content (r = -0.909, P = 0.091). The viscosity coefficient, eta1, was negatively correlated to amylose (r = -0.915, P = 0.085). The analysis between creep parameters and sensory evaluation showed that the viscosity coefficient, eta1, positively correlated to stickiness and total evaluation of cooked rice. So it can be used to evaluate the eating quality of cooked rice.