Effects of amylose and amylopectin chain-length distribution on the kinetics of long-term rice starch retrogradation

Understanding the characteristics of long-term starch retrogradation is critical for developing functional foods with desirable textural attributes. The long-term retrogradation kinetics of 10 different rice starches with a wide range of amylose content were thus investigated in this study, focusing on their relations with the starch chain-length distributions (CLDs). Correlation analysis between the retrogradation parameters from differential scanning calorimetry (DSC) with starch CLDs showed for the first time that the amylose content had a parabolic relationship with the melting conclusion temperature and enthalpy of long-term retrograded starches, indicating that the amylose component has a bi-directional effect on the long-term amylopectin retrogradation property. Furthermore, the amount of amylose short-medium chains and amylopectin medium chains were negatively and positively correlated with the melting onset temperature of long-term retrograded starches, respectively. The information learnt from this study could be applied in the rice industry to improve the textural attributes of cooked rice.