Enhanced emulsifying properties of octenyl succinic anhydride starch by homogeneous modification in KOH/urea aqueous solution.

Octenyl succinic anhydride starch (OSA-starch) is a widely used food-grade emulsifier. However, the heterogeneous synthesis process resulting from insoluble starch granules limits the functional properties of OSA-starch (HeOSA-starch). In this study, KOH/urea solution was used to dissolve starch to prepare OSA-starch via homogeneous modification (HoOSA-starch), and its emulsifying properties were investigated. Homogeneous modification significantly improved the degree of substitution and dispersibility of OSA-starch. Emulsions stabilized by HoOSA-starch exhibited superior stability than those stabilized by HeOSA-starch with lower variations in backscattered light intensity and smaller droplet sizes. Gelatinization improved the dispersibility and emulsifying properties of HeOSA-starch, though they remained inferior to those of HoOSA-starch, suggesting that gelatinization cannot replicate the advantages of homogeneous modification. Increased electrostatic repulsion, surface activity, and interfacial film strength were the driving force for enhanced stability of HoOSA-starch stabilized emulsions. Overall, this study highlights the advantages of homogeneous modification in optimizing the functional properties of OSA-starch.