Saponins as Natural Emulsifiers for Nanoemulsions

Abstract

The awareness of sustainability approaches has focused attention on replacing synthetic emulsifiers with natural alternatives when formulating nanoemulsions. In this context, a comprehensive review of the different types of saponins being successfully used to form and stabilize nanoemulsions is presented, highlighting the most common natural sources and biosynthetic routes. Processes for their extraction and purification are also reviewed altogether with the recent advances for their characterization. Concerning the preparation of the nanoemulsions containing saponins, the focus has been initially given to screening methods, lipid phase used, and production procedures, but their characterization and delivery systems explored are also discussed. Most experimental outcomes showed that the saponins present high performance, but the challenges associated with the saponins' broader application, mainly the standardization for industrial use, are identified. Future perspectives report, among others, the emerging biotechnological processes and the use of byproducts in a circular economy context.

Camellia Saponin Based Oleogels by Emulsion-Templated Method: Preparation, Characterization, and in Vitro Digestion

“…CS is a kind of natural, plant-derived surfactant isolated from camellia seed oil press cake. Most are oleanane-type hydrophobic triterpene monodesmosides with three or four hydrophobic saccharide residues attached at C-3 . CS has strong surface activity due to its peculiar molecular structure (Figure A).…”

“…Most are oleanane-type hydrophobic triterpene monodesmosides with three or four hydrophobic saccharide residues attached at C-3. 30 CS has strong surface activity due to its peculiar molecular structure (Figure 1A). The interfacial properties of emulsifiers play an important role in foaming and stabilizing water-continuous emulsions.…”

Study of binary mixtures of Tribulus terrestris extract and Quillaja bark saponin as oil‐in‐water nanoemulsion emulsifiers

“…A recent review (Schreiner et al, 2022) on saponins as natural emulsifiers highlighted saponin-rich extracts as alternatives to Quillaja saponin and other highly pure saponins. These solutions are recognized as more sustainable and low-cost options.…”

“…Although Quillaja saponin proved to be an excellent surfactant, there is a current need to identify and apply alternative saponin sources mainly due to questions of sustainability and cost (Schreiner et al, 2022), also preventing the overexploitation of the Quillaja tree (Reichert et al, 2018). Some studies have reported the use of saponins extracted from the Yucca tree ( Yucca schidigera ) (Ralla, Salminen, Tuosto, et al, 2017; Tsibranska et al, 2020), sugar beet ( Beta vulgaris ) (Ralla, Salminen, Edelmann, et al, 2017), oat bran ( Avena sativa L.) (Ralla et al, 2018), tea saponin (Zhu et al, 2019), and argan press cake and shells (Bouhoute et al, 2020; Taarji et al, 2018).…”

“…These solutions are recognized as more sustainable and low‐cost options. In addition, the extracts can offer added value due to the presence of bioactive compounds in the mixture (Schreiner et al, 2022). Among them, for example, the saponin‐rich extract Tribulus terrestris (TT) from puncture vine presents antioxidant (Amin et al, 2006), antimicrobial, and cytotoxic effects (Akram et al, 2011).…”