There is strong drive towards the use of natural surfactants or biosurfactants which are biodegradable and biosustainable in products such as detergents, foods, cosmetics and pharmaceuticals. Saponins are a class of natural surfactants which have great potential in emulsion and foam stabilisation and have anti-inflamatory, anti-microbial and anti-viral properties. Preliminary measurements on the Escin and Tea triterpenoid Saponins have established their adsorption isotherms by NR, and rationalised their unusual surface rheology in terms on their detailed surface structure. We now wish to explore how the differences in the surface rheological properties with pH for the Escin saponin correlate with changes in the surface structure.
