Comparison of plant-based emulsifier performance in water-in-oil-in-water emulsions: Soy protein isolate, pectin and gum Arabic

The impact of natural emulsifier type on the fabrication, stability, and release attributes of water-in-oil-in-water (W/O/W) emulsions prepared with a high-shear mixer were investigated: gum arabic, high-methoxy pectin, whey protein isolate (WPI), and soy protein isolate (SPI). At 1 wt%, all emulsifiers produced W/O/W emulsions with similar mean droplet diameters (d32 = 23–25 μm). However, less pectin was required to form small droplets than gum arabic, WPI or SPI. The impact of emulsifier type on the transport of small ions between the aqueous phases was then examined by placing iodine and starch in the external and internal water phases, respectively. Iodine turned blue when it came into contact with starch. W/O/W emulsions prepared using proteins (SPI and WPI) were more effective at inhibiting mass transport than those prepared using polysaccharides (gum arabic and pectin). These results are useful for rationalizing the selection of biopolymer emulsifiers for application in double emulsions.