Insight Into Foam Properties of Natural Saponins with Low-pH and High-Temperature Tolerance from Xanthoceras sorbifolium Bunge Leaves for Industry Applications

In foam products, awareness of sustainable approaches has focused attention on the replacement of synthetic surfactants with natural alternatives. However, commonly used natural surfactants are sensitive to acidity and high temperature, which reduce the foaming property. In this study, the physicochemical and foam properties of natural saponins from Xanthoceras sorbifolium Bunge leaves (XLs) as foam agents under industry-relevant conditions were studied. Results found that XLs saponins exhibited remarkable foaming ability and foam stability and resistance to low-pH and high-temperature. Further, the decrease in pH and the increase in temperature could decrease the surface tension. In addition, conductivity, particle size and zeta potential results showed that decreasing pH and increasing temperature could reduce the critical micelle concentration values of XLs saponins, thus forming additional micelles and increasing the viscoelasticity of the saponins solution. The enhancement of these properties contributed to forming a foam with favorable stability at low-pH and high-temperature. Such XLs saponins are promising natural alternatives to traditional food or cosmetic foaming agents.