Ability of Sodium Dodecyl Sulfate (SDS) Micelles to Increase the Antioxidant Activity of α-Tocopherol

As emulsifiers become saturated on the surface of an emulsion droplet, any additional emulsifier migrates to the aqueous phase. Continuous phase surfactants have been shown to increase alpha-tocopherol efficacy, but it is unclear if this is the result of chemical or physical effects. The addition of alpha-tocopherol to an oil-in-water emulsion after homogenization resulted in a 70% increase of alpha-tocopherol in the continuous phase when sodium dodecyl sulfate (SDS) was at levels that were greater than the SDS critical micelle concentration. Conversely, when alpha-tocopherol was dissolved in the lipid before emulsification, continuous phase SDS concentrations did not increase. When SDS concentration led to an increase in the aqueous phase alpha-tocopherol, the oxidative stability of oil-in-water emulsions increased. Data indicated that the increased antioxidant activity was the result of surfactant micelles being able to decrease the prooxidant activity of alpha-tocopherol. Considering these results, surfactant micelles could be an important tool to increase the effectiveness of alpha-tocopherol.