Utilization of octenyl succinic anhydride-modified pea and corn starches for stabilizing oil-in-water emulsions

Abstract

In this study, pea starch (41.5% amylose), normal corn starch (32.9% amylose), and waxy corn starch (1.7% amylose) were modified using three concentrations of octenyl succinic anhydride (OSA). The degrees of substitution, thermal properties, and pasting properties of the derived OS-starches were determined. Canola oil-in-water (O/W) emulsions were prepared using a high-pressure homogenizer with the OS-starches to evaluate their emulsifying properties, with gum Arabic (GA) being included as the industry standard for comparison. Droplet-size distributions, zeta potentials, accelerated stability, and storage stability of the resultant emulsions were determined and compared. Emulsion stability under various environmental conditions was also investigated, including pH 2–7, 0–1.0 M sodium chloride in aqueous medium, and incubation at 90 °C for 30 min. Overall, the ability of the emulsifiers in stabilizing O/W emulsions followed an ascending order of OS-PS < GA ≤ OS-NCS < OS-WCS. Emulsifying properties of the OS-starches and stability of the resultant emulsions were generally enhanced with a higher degree of substitution. The interrelationships among the molecular structures (e.g., amylose content and degree of substitution), functional properties (e.g., retrogradation rate), and emulsifying ability of the OS-starches were also elucidated. The new findings from the study can be used to further tailor the structures of OS-PS to improve the emulsifying properties for potential industrial uses.