Characteristics of sweet potato starch particles modified by various methods for use in food-grade Pickering emulsion

Abstract

The objective of the current work was to formulate Pickering emulsions prepared solely of sweet potato starch that were renewable and surfactant-free. Native starch has a low capacity for emulsification, for this reason, three different modification techniques including anti-solvent precipitation, esterification with octenyl succinic anhydride (OSA), and hydrothermal treatment were applied to modify native sweet potato starch particles (NSPSP). The outcomes demonstrated that the characteristics of the particles, such as size, wettability, surface morphology, crystallinity, thermal behavior, and interfacial tension, were significantly impacted by modification. The amylose content and roughness of NSPSP were reduced by applying OSA, and OSA-modified samples had the highest contact angle and crystalline region. Conversely, ethanol-induced starch granules showed increased amorphous area, higher surface roughness, and agglomeration. From an interfacial perspective, esterification of starch with OSA could decrease the interfacial tension, whereas the anti-solvent approach caused an increase in this parameter. Droplet size, surface charge, microstructure, and emulsification index were used to describe O/W Pickering emulsions stabilized by native and modified particles. This investigation suggested that, in contrast to the other two techniques, modifying NSPSP with OSA had a favorable effect on the emulsifying capacity of the resulting Pickering emulsion. The findings suggested that modified NSPSP could be a promising candidate to stabilize Pickering emulsion with demanding characteristics, which could be applied for carrying the bioactive compounds.