Abstract: Surfactin was used as a surfactant to form docosahexaenoic acid (DHA)-rich algae oil emulsion. It was found that oil-in-water (O/W) DHA-rich algae oil emulsion without added cosurfactant or any other additive where the aqueous phase was 0.8% surfactin had better physical stability at 4 and 37 ℃ than emulsions formed with other surfactants. DHA-rich algae oil emulsion with surfactin had significant advantages (P < 0.05) in turbidity, particle size, Zeta potential, and rheological properties than those with Tween-80-glycerol or other food-grade surfactants. Oxidation stability of DHA-rich algae oil emulsion with surfactin was also excellent after treatment at high temperature or during storage time at room temperature. The peroxide value remained at low level, which was (1.635 ± 0.202) meq/kg after storage at 37 ℃ for 60 days.

Key words: surfactin, DHA-rich algae oil emulsion, physical stability, oxidation stability