Interaction of surface active agents with lecithin at the xylene/water interface and its effect on the stability of the resulting emulsion

Linker-based bio-compatible microemulsions

In this work we have studied the formulation of biocompatible microemulsions using lecithin as the main surfactant and bio-compatible linker molecules (hexyl polyglucoside asthe hydrophilic linker and sorbitan monoleate as the lipophilic linker). These bio-compatible systems are discussed as potential substitutes for chlorinated solvents in dry-cleaning applications and as solvent delivery systems for pharmaceutical applications. Formulation parameters and conditions were evaluated using isopropyl myristate (IPM) as the model oil. It was found that the proposed linker-based formulations were able to form alcohol-free microemulsions while achieving higher solubilization capacity than similar systems reported in the literature. In addition, these lecithin/linker formulations were able to form microemulsions with a wide range of oils, from polar chlorinated hydrocarbons to hydrophobic oils such as squalene. These microemulsions were achieved under isotonic conditions (0.9% NaCl) by only varying the relative proportions of the linkers. The "solvency" power of these bio-compatible formulations was tested for the removal of hexadecane (used as model oil) from cotton fabrics and compared to the solvency power of a typical dry cleaning solvent tetrachloroethylene (PCE). While PCE and the linker-based lecithin formulation removed the same amount of hexadecane at low loading ratios (less than 1% oil volume fraction), at higher loading ratios the linker-based lecithin formulation retained its oil removal capacity while the efficiency of the PCE system declined rapidly. These initial results thus demonstrate the remarkable oil solubilization capacity of these bio-compatible linker-based lecithin formulations and illustrate their potential as environmentally friendly replacements for organic solvents.

Properties and functions of stabilizing agents in food emulsions

This review outlines the state of knowledge concerning the basic processes which underlie the behavior of food stabilizers in practical applications. The stability of emulsions is discussed in terms of the forces acting between macroscopic colloidal particles. These forces include the van der Waals force of attraction, which is always present, and the electrostatic, steric, and hydration forces which may stabilize an emulsion since they can be repulsive. The adsorption behavior at the liquid/liquid interface of classes of typical food stabilizers and the influence of the absorbed layer on the droplet-droplet interactions in emulsions are discussed. Finally, the important effects of the surface-active properties of stabilizers on the mechanisms involved in emulsion formation are described.