Improvement of Amphiphilic Properties of High and Low Amylose Rice Starch through Chemical and Physical Modification and its Functionality in an Emulsion System

Native rice starch has functional limitations such as poor solubility, heat tolerance, and emulsifying properties, which restrict its industrial applications. To address these deficiencies, this study investigated the modification of rice starch using octenyl succinic anhydride (OSA), followed by physical modifications like pre-gelatinization (PG) and granular starch (GS) treatments. High amylose (HA) and low amylose (LA) rice starches were sourced, modified, and characterized. The degree of substitution (DS) analysis revealed higher substitution in HA-OSA starch (0.012 ± 0.001%) than in LA-OSA starch (0.009 ± 0.001%). Functional properties like oil and water absorption, and water solubility were enhanced in PG starches compared to GS starches. Emulsion stability tests demonstrated that OSA-modified starches effectively stabilized oil-in-water emulsions, with HA-PG showing the highest elastic properties and stability due to its robust three-dimensional network formation. Light and confocal microscopy confirmed the complete covering of oil droplets by starch molecules, enhancing emulsion stability through steric hindrance. These findings suggest that OSA-modified rice starch, particularly HA-PG, is a promising alternative to synthetic emulsifiers, offering a green solution for the food, pharmaceutical, and personal care industries.