Reichert Corina L, Salminen Hanna, Leuenberger Bruno H, Weiss Jochen
Department of Food Physics and Meat Science, Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstraße 21/25, 70599 Stuttgart, Germany.
DSM Nutritional Products, Research and Development, P.O. Box 2676, 4002 Basel, Switzerland.
Food Res Int. 2016 Oct;88(Pt A):16-23. doi: 10.1016/j.foodres.2016.03.034. Epub 2016 Apr 5.
Thermal treatment of mixed surfactant systems can have a major impact on their phase behavior through modified interactions between the surfactants. In this study, we investigated the miscibility behavior of aqueous binary surfactant systems composed of Quillaja saponin extract and sodium caseinate, pea protein, rapeseed lecithin, or egg lecithin at different concentration ratios (0-5% w/v) at pH3, 5, and 7 upon heat treatment (25-75°C). The results revealed that the heat-treated Quillaja saponin-sodium caseinate mixtures at pH7 remained miscible when the ratio of Quillaja saponins was equal or higher to the ratio of caseinate, otherwise the mixtures flocculated due to increased hydrophobic interactions. At pH3, the aggregation of Quillaja saponin-sodium caseinate structures was intensified by heating mainly through self-association of casein molecules. In Quillaja saponin-pea protein mixtures as well as in pure pea protein samples heating led to weakening of the gel structures at all tested pH values. In contrast, heating did not affect Quillaja saponin-rapeseed lecithin mixtures, which stayed miscible independent of pH due to electrostatic repulsive forces. Furthermore, the flocculated (pH5, 7) or aggregated (pH3) Quillaja saponin-egg lecithin mixtures were only slightly affected by heating. These results are important for understanding the interactions of binary surfactant systems when subjected to heating, which is a common processing step in many food applications.
