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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.