Effect of amorphous degree on the structure of octenyl succinate anhydride starch and emulsion stability

Octenyl succinic anhydride starch (OSAS) has potential applications for stabilizing oil-water interfaces to form stable emulsions. In this study, amorphous OSAS (AOS) with varying degrees of amorphization (DA) were produced through hydrothermal treatment at 70, 80, and 90 °C, followed by spray drying. This study aims to investigate the structural properties of these starches, including particle size, rheological properties, followed by an analysis of the principles behind their stabilization of the oil-water interface. The AOS demonstrated a more loosely organized helical structure and a higher elastic modulus as the DA content increased. Additionally, AOS adsorbed onto the oil-water interface in a more flexible chain form throughout the stabilization process. AOS90 could reduce the critical micelle concentration (CMC) to 0.934 mg/mL, which promoted the formation of the interfacial film. It created an interfacial film resembling a solid at an adsorption rate of up to 42.52 % and an emulsion activity of 23.07 m²/g. The emulsion displayed good stability in dynamic light scattering tests as DA increased and may be suitable for developing functional emulsions for fat substitutes and the delivery of bioactive substances.