Influence of degree of substitution of octenyl succinic anhydride starch on complexation with chitosan and complex-stabilized high internal phase Pickering emulsions

We analyzed the effects of the degree of substitution (DS) of octenyl succinic anhydride starch (OSA-S) on OSA-S/ chitosan complexes and complex-stabilized high internal phase Pickering emulsions (HIPPEs). Because of its low charge density, OSA-S with lower DS weakly interacted with chitosan, forming loosely structured and small-sized complexes. In contrast, OSA-S with higher DS produced complexes four-fold larger in size, with denser structures and enhanced wetting properties. All HIPPEs exhibited gel network structures, and their viscoelasticity and stability significantly increased with increasing DS. This may be related to the enhanced adsorption of the high DS complexes at the oil-water interface, which was verified by the excellent 3D-printing performance of emulsions. Moreover, HIPPEs showed high resistance to heat treatment and ionic strength but were strongly influenced by pH adjustment. Overall, the role of DS in fabrication of HIPPEs was confirmed, and the research for new applications in food industries was motivated.