Mechanistic Understanding of the Relationships between Structure and Digestibility of Octenyl Succinic Anhydride Modified Corn, Potato, and Pea Starch Nanoparticles

Abstract This study characterizes the digestibility properties and structural changes of octenyl succinic anhydride (OSA) modified starch nanoparticles (OSPNs) from corn, potato, and pea starches (codes as OCSNPs, OPtSNPs, and OPSNPs). After OSA modification, the average particle size and degree of substitution of OSPNs significantly (p < 0.05) increase compared to control samples, whereas the apparent amylose content, R1047/1022, relative crystallinity, and melting enthalpy are found to decrease significantly (p < 0.05), with the extent depending on the type of starch. In vitro digestibility tests show that OSA treatment converts part of rapidly digestible starch into slowly digestible starch and resistant starch for OSPNs, an effect that is more pronounced for OPtSNPs compared to OCSNPs and OPSNPs, corresponding to a reduce in equilibrium starch hydrolysis percentage and apparent digestion rate coefficient. Overall, the starch type affects the structural and digestibility properties of OCSNPs, OPtSNPs, and OPSNPs, with the most obvious effect observes for OPtSNPs.