Kinetics of volume expansion properties of cooked rice and correlation analysis upon the physicochemical factors with image analysis

A novel image analysis method was developed to determine the volume expansion ratio of cooked rice, and study the kinetics of the volume expansion ratio changes of rice as a function of the cooking time. The correlation between volume expansion ratio and various physicochemical factors has been studied to elucidate the key factors affecting the changes in cooked rice volume. The results demonstrated that the image analysis method is capable of both visually and quantitatively analyzing the volume expansion properties of rice throughout the cooking process. This method revealed that five models can effectively simulate (with a correlation coefficient R-2 > 0.95) the changes in the volume expansion ratio for Koshihikari and Thai Jasmine rice as a function of cooking time. These models consider cooking time as a variable. Consequently, a linear equation based solely on cooking time was derived, which can predict the volume expansion ratio of rice during the cooking process. The correlation analysis suggested that the apparent amylose content, protein content and grain length had significantly (P < 0.05) negative correlation with the volume expansion ratio; while starch content and grain width had significantly (P < 0.05) positive correlation with the volume expansion ratio; the pasting properties parameters had different relationships with the volume expansion ratio of cooked rice.