title: Miscibility of Quillaja Saponins with other Co-surfactants under Different pH Values.
abstract: The miscibility behavior of mixed surfactant systems and the influence of extrinsic parameters are crucial for their application as emulsifiers. Therefore, the objective of this study was to evaluate the miscibility behavior of mixed systems composed of commercial Quillaja saponin and a co-surfactant, namely sodium caseinate, pea protein, rapeseed lecithin, or egg lecithin. These mixtures were evaluated macro- and microscopically at different concentration ratios (maximum concentration 5% w/v) at pH 3, 5, and 7 at 25 °C. The individual ingredients were also assessed for their charge properties and surface hydrophobicity. The results showed that Quillaja saponin-caseinate mixtures were miscible only at pH 7, and showed aggregation and precipitation at lower pH due to increasing electrostatic attraction forces. Rheological measurements showed that Quillaja saponin-pea protein mixtures formed gelled structures at all tested pH values mainly via association of hydrophobic patches. Quillaja saponins mixed with rapeseed lecithin were miscible at all tested pH values due to electrostatic repulsion. Quillaja saponin-egg lecithin mixtures aggregated independent of pH and concentration ratio. The microscopic analysis revealed that the lower the pH and the higher the Quillaja saponin ratio, the denser were the formed Quillaja saponin-egg lecithin aggregates. The results are summarized in ternary phase diagrams that provide a useful tool in selecting a surfactant system for food applications.
authors.affiliation: Dept. of Food Physics and Meat Science, Inst. of Food Science and Biotechnology, Univ. of Hohenheim, Garbenstraße 21/25, P.O. Box 70599, Stuttgart, Germany.
authors.forename: Corina L
authors.initials: CL
authors.lastname: Reichert
authors.affiliation: Dept. of Food Physics and Meat Science, Inst. of Food Science and Biotechnology, Univ. of Hohenheim, Garbenstraße 21/25, P.O. Box 70599, Stuttgart, Germany.
authors.forename: Hanna
authors.initials: H
authors.lastname: Salminen
authors.affiliation: DSM Nutritional Products, Research and Development, P.O. Box 2676, 4002, Basel, Switzerland.
authors.forename: Bruno H
authors.initials: BH
authors.lastname: Leuenberger
authors.affiliation: Dept. of Soft Matter Science and Dairy Technology, Inst. of Food Science and Biotechnology, Univ. of Hohenheim, Garbenstraße 21, 70599, Stuttgart, Germany.
authors.forename: Jörg
authors.initials: J
authors.lastname: Hinrichs
authors.affiliation: Dept. of Food Physics and Meat Science, Inst. of Food Science and Biotechnology, Univ. of Hohenheim, Garbenstraße 21/25, P.O. Box 70599, Stuttgart, Germany.
authors.forename: Jochen
authors.initials: J
authors.lastname: Weiss
mesh_terms: D045703:Emulsifying Agents / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D057927:Hydrophobic and Hydrophilic Interactions; D031990:Quillaja / Q000737:chemistry*; D062605:Quillaja Saponins / Q000737:chemistry*; D012212:Rheology; D055672:Static Electricity; D013501:Surface-Active Agents / Q000737:chemistry
chemical_list: D045703:Emulsifying Agents; D062605:Quillaja Saponins; D013501:Surface-Active Agents
keywords: Quillaja saponin; lecithin; miscibility; protein; surface hydrophobicity