Main content area

Concentration effect of Quillaja saponin – Co-surfactant mixtures on emulsifying properties

Reichert, Corina L., Salminen, Hanna, Badolato Bönisch, Gabriela, Schäfer, Christian, Weiss, Jochen
Journal of colloid and interface science 2018 v.519 pp. 71-80
Quillaja, additive effect, adsorption, droplets, eggs, emulsifying properties, emulsions, lecithins, pH, particle size, pea protein, rapeseed, saponins, surface tension, surfactants
This study examined the emulsifying properties of mixed surfactant systems of Quillaja saponins and food-grade co-surfactants (Na-caseinate, pea protein, rapeseed lecithin, and egg lecithin). We hypothesized to these mixtures may build mixed adsorption layers and thus enhance emulsion stabilization.Oil-in-water emulsions (10%, pH 7) were prepared with different concentrations of co-surfactants (0.1–5.0%) alone or mixed with Quillaja saponins (0.05 or 0.5%). Dynamic interfacial tension measurements were performed to characterize the behavior of the surfactants at an oil-water interface.Low Quillaja saponin concentrations led to either no changes or substantial increases in particle sizes of protein stabilized emulsions, but d43-values decreased in lecithin stabilized emulsions at low lecithin concentrations. The dominating effect of Quillaja saponins at high concentrations led to formation of small droplets (d43≤2 µm) in all emulsions, except with 2.5% pea proteins. All co-surfactants showed synergistic or additive effects with respect to interfacial tension reductions upon addition of Quillaja saponins (except for egg lecithin with 0.005% Quillaja saponin addition). The results indicated a competing effect for saponin–protein interfaces, but formation of mixed saponin–lecithin interfaces, thus showing that the emulsion stabilization and interfacial properties can be tuned by specific binary surfactant mixtures.