Development of sophorolipid-chitosan pickering O/W emulsion formulations

Sophorolipids (SL) are well-known biosurfactants produced by the yeast S. bombicola, generally in a complex mixture between its lactonic and open acidic forms, both being partially acetylated. To overcome this issue, by alkaline hydrolysis we generate a fully acidic, non-acetyalted, form of SL. This acidic SL has a pH-responsive behaviour and above pH 6 can form complex coacervates with high-molecular weight chitosan by a simple mechanism of electrostatic attraction between the negative and positive forms of SL and chitosan, respectively. SL-chitosan complex coacervates are able to stabilize O/W emulsions by a Pickering mechanism. We show here their application in the formulation of O/W emulsions containing cosmetics-relevant raw materials, oils, preservatives and vitamins.