Partitioning of vanillic acid in oil-in-water emulsions: Impact of the Tween®40 emulsifier

• A methodology to measure the vanillic acid content of each phase in o/w systems has been developed.
• Tween®40 emulsifier added in o/w systems modifies the partitioning of vanillic acid.
• Tween®40 transfers some vanillic acid from oil and water into Tween micelles and at the oil/water interface.
• Interactions between Tween®40 and vanillic acid are revealed in aqueous solutions using fluorescence spectroscopy.

Tween®40, a non-ionic emulsifier, was studied regarding its influence on the partitioning of vanillic acid, chosen as a model of phenolic antioxidants, in oil/water emulsions. Three oil-in-water (30:70) systems at pH 3.5 were compared: an oil/water two-phase system, a system with oil/water/Tween just mixed, and an emulsified oil/water/Tween system. The partitioning of vanillic acid in the aqueous and oily phases was studied by 2D front-face fluorescence spectroscopy and UV spectroscopy. Tween®40 used at two concentrations 0.9% and 3.6% was only partitioned in the aqueous phase and at the interface between oil and water.Vanillic acid in the oil/water two-phase system reflected its amphiphilic nature: 3/4 was partitioned in the aqueous phase and 1/4 in the oily phase. In the presence of Tween®40, the major part of vanillic acid (90%) was found in the aqueous phase of the non-emulsified system, where a high proportion was associated with Tween®40 micelles. In the emulsion system, vanillic acid moved with Tween®40 to the o/w interface of the oil droplets. Fluorescence analyses demonstrated that the interactions between vanillic acid and Tween®40 were dependent on pH.

A non-destructive methodology has been developed to measure the partition of antioxidant and emulsifier in each phase of different o/w systems.Figure optionsDownload as PowerPoint slide