The influence of non-ionic surfactant on lipid digestion of gum Arabic stabilized oil-in-water emulsion

- The addition of tween 80 in the gum arabic - stabilized emulsion exhibited a biphasic rate of lipid digestion.
- Addition of tween 80 to the gum arabic films contributed to the formation of network at air-water interface.
- The accumulation of lipase adsorption on emulsion droplets interface corresponds exactly to the lag period of FFA released.
- It was proved that the biphasic rate of lipid digestion was mainly caused by the lipase adsorption rate.

Lipid digestion is the process of enzymatic hydrolysis at the interface, and the interfacial structure play an important role in the lipid digestion. Non-ionic surfactant Tween80 (T80) presented a significant impact on the lipid digestion of gum Arabic (GA) stabilized oil-in-water emulsion. The interfacial structure of GA-T80 emulsion droplets has been investigated by using gel permeation chromatography-multiangle laser light scattering, interfacial measurement and atomic force microscope. With addition of T80, the surface loading of GA decreased until a plateau value reached. About 15% of GA still remained on the interface when T80 concentration increased to ∼4%. Addition of T80 contributed to a stiffening of the network formed at the droplets interface. The kinetics of lipid digestion exhibited a biphasic rate under this certain interface, shown as an induction period followed by a speeding up process. It probably resulted from the adsorption behavior of lipase on the emulsion interface during the lipolysis process. In was found that the accumulation of lipase on the emulsion droplets interface contributed to the lag period of the free fatty acids release. The biphasic rate of lipid digestion was mainly caused by the rate of lipase adsorption, which was highly dependent on the interface structure of emulsion droplets.

The concentration of lipase adsorbed on the emulsion droplets interface at different digestive stages during in vitro digestion of 10% gum arabic - 1.6% Tween80 emulsion. Triangles represent lipase concentration, and circles the FFA released curves. It is proved that the accumulation of lipase on the emulsion droplets interface contributed to the lag period of FFA release. The lipolysis would quickly start when the lipase adsorption on the droplets interface reached to a plateau.141