Effect of debranching on the structure and digestibility of octenyl succinic anhydride starch nanoparticles

Abstract

Starch nanoparticles are known to have potential applications in the encapsulation and delivery of active substances. In this study, waxy maize starch (WMS) was modified with octenyl succinic anhydride (OSA), followed by debranching with pullulanase to obtain linear chains with OSA groups. These chains self-assembled and polymerized into nanoparticles. The structural characteristics of these particles, including the molecular weight, chain length distribution, particle size, and digestibility were investigated. The results indicated that the A-type crystalline structure of the WMS and OSA-modified starch changed to a B-type structure after debranching. Compared with WMS, at a low degree of substitution (DS = 0.016), there was less change in particle size, amylose content, and molecular distribution after debranching. When the DS was high (DS = 0.027, DS = 0.036), the molecular weight distribution of the OSA starch showed three peaks, and the short chain in the starch after debranching was relatively large. Moreover, the resistant starch content of the nanoparticles increased from 3.9% to 30% in WMS. Particle sizes ranged from 100 nm to 300 nm, and OSA-modified nanoparticles had a lower zeta potential and better stability. This method for preparing nanoparticles is potentially applicable to the preparation of delivery carrier materials for active functional substances.