Effects of ascorbic acid on the microstructure and properties of SDS micellar aggregates for potential food applications

Self-assembled colloidal aggregates are used for the in vitro replication of some biological processes such as chemical reactions, and organic and inorganic transport phenomena, occurring in food. It would therefore be interesting to assess the interaction between ascorbic acid and micellar aggregates via changes in packing and the air-water interface. To this end, we developed a simple, easily controlled one-pot strategy for examining the effects of the acid on biomimetic self-assembled aggregates of sodium dodecyl sulphate (SDS). This surfactant is used for a variety of purposes involving oily materials, and, in association with ascorbic acid, has been found to act as both a reductant and a stabilizer. Research into the mechanism behind this interaction suggests that ascorbic acid in aqueous solutions of SDS promotes micellization by effect of either an increase in concentration of the additive (the acid itself) at a constant temperature or an increase in temperature at a constant additive concentration. Ascorbic acid competes with SDS for available positions at the air-water interface. Displacement of SDS by ascorbic acid molecules at the interface is favoured by an increased temperature. Also, the acid significantly alters the structure of the hydration sphere of an amphiphilic molecule such as SDS and its minimum surface area per molecule as a result. (c) 2012 Elsevier Ltd. All rights reserved.