Interfacial adsorption behavior and interaction mechanism in saponin–protein composite systems: A review

Proteins are important foaming agents and emulsifiers in food processing, but protein molecules are adsorbed slowly. Recently, surfactants, such as saponins, have garnered considerable attention due to their ability to adsorb on the interface quickly. Therefore, combinations of proteins and surfactants can compensate for the shortcomings of both components. With the pursuit of health, natural surfactants have gradually become mainstream, and the interfacial properties of proteins and saponins have also been studied extensively. This review first introduces two common saponins and typical proteins in food, and then describes the interfacial (air-water and oil-water) properties of the complex systems they form and the interaction forces that arise between the two components at the microscopic level to maintain the equilibrium state of the interfacial film. Additionally, examples of foaming and emulsification properties of these complex systems in food applications are presented. Some common methods for studying the interaction mechanisms are summarized to provide a theoretical basis for clarifying the properties of saponins and proteins at the macroscopic interface and the influence of these interactions on complex food systems.