Influence of Octenyl Succinic Anhydride Modification on Physicochemical and Functional Properties of Rice Starches With Varying Amylose Content

Abstract

Amylose content and octenyl succinic anhydride (OSA) modification significantly influence the physicochemical and functional properties of rice starches. Although OSA modification of rice starch has been widely studied, the relationship between intrinsic structural variability among rice cultivars and amylose‐dependent differences in OSA reactivity is still not fully established. This study evaluated OSA modification of rice starches with different amylose contents. OSA modification reduced amylose in all samples. Degree of substitution (DS) was inversely related to amylose content, with Motti starch showing the highest DS. Structural and functional changes were observed, including decreases in gelatinization temperature and water absorption capacity. Termogravimetric analysis showed higher final degradation temperatures but greater mass loss in modified starches. Pasting properties were significantly altered, with higher breakdown and lower setback values, indicating enhanced paste stability and reduced retrogradation. X‐ray diffraction patterns revealed decreased crystallinity after modification, consistent with esterification occurring in amorphous regions. Except for Irga 417 starch, where resistant starch (RS) increased after modification, no significant differences in in vitro digestibility were observed. Overall, the results provide new insights into the role of amylose content in governing OSA reactivity and functional behavior of rice starch.