Debranching and OSA esterification of waxy maize starch: effects on nanoparticle properties and emulsion performance

Waxy maize starch (WMS) was modified sequentially via two pathways: pullulanase debranching followed by octenyl succinic anhydride (OSA) esterification or the reverse sequence (esterification followed by debranching) to obtain OSA-esterified debranched starch (OS-DBS, 305.45 nm) and debranched OSA-esterified starch (DB-OSS, 166.56 nm) nanoparticles. Debranching transformed the A-type crystalline structures of WMS and OSS into amorphous states. Fourier-transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) analyses confirmed that DB-OSS underwent intramolecular chain folding, leading to a significantly lower number of surface-exposed OSA groups than OS-DBS (p < 0.05). The evaluation of emulsification performance demonstrated that DB-OSS exhibited superior emulsifying capability, with an interfacial starch adsorption value of 38.8%. After 28 days of storage, the DB-OSS-stabilized emulsions retained their structural integrity with only slight phase separation observed, and the emulsifying index remained at 0.72. Overall, these results indicate that the esterification-debranching sequence yields starch nanoparticles with optimal structural characteristics and emulsion performance.