STABILITY OF EMULSIONS STABILIZED BY 2 PHYSIOLOGICAL SURFACTANTS - L-ALPHA-PHOSPHATIDYLCHOLINE AND SODIUM TAUROCHOLATE

The emulsion phase formed within the stomach and duodenum during diges tion of a fatty meal has been modelled using two physiological surfact ants, the phospholipid L-alpha-phosphatidylcholine (PC) and the bile s alt sodium taurocholate (NaT). Upon dilution of the phospholipid stabi lised emulsions with a solution of NaT the bile salt became incorporat ed into the oil/water interface imparting a negative charge to the dro plet surface. The magnitude of the droplet microelectrophoretic mobili ty for the mixed PC and NaT system was 47% of that found for emulsion droplets stabilised by NaT alone. But the electrostatic repulsion betw een droplets was not sufficient to account for the observed improvemen t in emulsion stability to coalescence. It is suggested that a residua l liquid crystalline phospholipid interface is present imparting a sig nificant steric component to the stabilisation of the emulsions drople ts.