Emulsifying stability properties of octenyl succinic anhydride (OSA) modified waxy starches with different molecular structures

Abstract

Octenyl succinic anhydride (OSA)-modified waxy starches are used widely as emulsifiers and stabilizers in the food and beverage industry. Selection of appropriate OSA-starch and oil phase is important to ensure that emulsion-based products exhibit desired properties and are stable. Here, we studied the structural characterization, and interfacial properties of three OSA-starches with different multi-scale molecular structures (OSA-W1, OSA-W2, and OSA-W3) and their emulsifying stabilities when combined with various different food-grade oil phases (medium-chain triglyceride (MCT), corn oil, and palm oil). Interfacial tension decreased as the degree of substitution (DS) of OSA-starches increased. Compared with OSA-W1, OSA-W2 exhibited a greater hydrodynamic radius (Rh). The OSA-W2 based emulsion, possessing the largest droplets, was sensitive to droplet size increase (from 255 to 299 nm) due to crosslink between droplets, but stable to gravity separation (ΔT, the difference in transmission between the bottom and middle layers, was only 0.2% after 30 days). OSA-W3, with the highest DS (3.83%) and smallest Rh, formed fine stable emulsion droplets that did not increase substantially in diameter during storage (180 nm initially, 190 nm after 30 days), but exhibited poor gravitational stability (ΔT = 26.2% after 30 days). Of the three oils tested, the MCT oil-in-water emulsion had the greatest stability and maximum oil loading; appropriate absorbance of starch on the surface created a strong interface. Thus, we provide valuable information guiding the selection of appropriate OSA-starch and oil phase for use in the food and beverage industry.