Comparative study of RS4 type resistant starches derived from cassava and potato starches via octenyl succinylation

Resistant starch is becoming important among functional foods because of its similarity to dietary fiber in many physiological properties. In the present study, an attempt has been made to compare two distinct tuber starches from cassava and potato, in the formation of RS4 type resistant starch by chemical modification with octenyl succinic anhydride (OSA). The octenyl succinate esters of both the starches exhibited significant changes in structural, functional, and dietetic properties in comparison to their respective native counterparts. The modified starches were characterized by FTIR, SEM, and XRD analysis. The pasting, gelatinization, and in vitro digestibility properties were also determined. The water binding capacity of both the starches increased upon modification. The pasting and gelatinization properties of the two starches were affected differently. The cooked samples of octenyl succinylated potato starch showed slowly digestible starch (SDS) and resistant starch (RS) in the range of 10.53-34.86% and 3.58-29.1%, respectively, whereas these were 20.46-38.36% and 1.47-27.92%, respectively, for cassava starch. In both cases, RS and SDS of modified starches increased significantly and glycemic index (GI) decreased in comparison to corresponding native starches.