Abstract:As a large class of glycosides, saponins are widely distributed in natural plant kingdom, has received extensive attention in recent years. In terms of molecular structure, natural saponins are composed of hydrophobic aglycone backbones of triterpenoids or steroidal glycosides (hydrophobic scaffolds) attached with hydrophilic sugar chains, resulting in a high surface activity. The structural diversity of natural saponins not only makes them possessing biological activity and unique physicochemical properties, but also promotes a wide range of applications in foods, cosmetics and other fields. Based on the recent research on the structural characteristics, self-assembly and interface properties of natural saponins, this study attempts to explore the effect of the structure on the assembly behavior at aqueous phase, and air-water interfaces, oil-water interfaces and solid-liquid interfaces, and on the functional characteristics of food colloids. Moreover, the self-assembly and interfacial structures may vary with the plant source and molecular structure: Saponins with a triterpenoid structure most likely form viscoelastic interfacial membranes, resulting in stable food colloids; while saponins with a steroid structure tend to possess special physiological activities. Among them, natural Quillaja saponins perform at their best. They have been proven capable of forming stable micelles, nanoemulsions, emulsion gels and foams for the delivery of bioactive substances, and gained approval for food applications in most ocountries such as China, the United States and the European Union.
