Starch fine molecular structures as driving factors for multiphasic starch gelatinization property in rice flour

Abstract Background and Objectives Although the gelatinization property of isolated rice starch has been investigated in terms of its relationship to starch fine molecular structures, it remains unclear how these structures determine the gelatinization property of rice flour. The gelatinization properties of 10 rice flours with varying chain‐length distributions were thus studied. Findings Rice flours with larger amylose molecules, longer and higher amount of amylopectin intermediate chains showed double gelatinization peaks. The onset and peak temperatures of gelatinization for the peak having a lower gelatinization temperature showed a positive correlation with the molecular size of amylopectin. Conversely, the conclusion temperature of gelatinization for the peak with a higher gelatinization temperature exhibited a negative correlation with the molecular size of amylose and a positive correlation with the quantity of amylose and amylopectin intermediate chains. These correlations were largely different compared with those for rice flours with a single gelatinization peak. Conclusions These results supplied the first associations between gelatinization property of rice flour and starch fine molecular structures, which were different from those for pure rice starches. Significance and Novelty These results have the potential to assist the food industry in developing rice products with improved quality, depending on the molecular structure of the starch.