Concentration effect of Quillaja saponin – Co-surfactant mixtures on emulsifying properties

Perspectives on Saponins: Food Functionality and Applications

Saponins are a diverse group of naturally occurring plant secondary metabolites present in a wide range of foods ranging from grains, pulses, and green leaves to sea creatures. They consist of a hydrophilic sugar moiety linked to a lipophilic aglycone, resulting in an amphiphilic nature and unique functional properties. Their amphiphilic structures enable saponins to exhibit surface-active properties, resulting in stable foams and complexes with various molecules. In the context of food applications, saponins are utilized as natural emulsifiers, foaming agents, and stabilizers. They contribute to texture and stability in food products and have potential health benefits, including cholesterol-lowering and anticancer effects. Saponins possess additional bioactivities that make them valuable in the pharmaceutical industry as anti-inflammatory, antimicrobial, antiviral, and antiparasitic agents to name a few. Saponins can demonstrate cytotoxic activity against cancer cell lines and can also act as adjuvants, enhancing the immune response to vaccines. Their ability to form stable complexes with drugs further expands their potential in drug delivery systems. However, challenges such as bitterness, cytotoxicity, and instability under certain conditions need to be addressed for effective utilization of saponins in foods and related applications. In this paper, we have reviewed the chemistry, functionality, and application aspects of saponins from various plant sources, and have summarized the regulatory aspects of the food-based application of quillaja saponins. Further research to explore the full potential of saponins in improving food quality and human health has been suggested. It is expected that this article will be a useful resource for researchers in food, feed, pharmaceuticals, and material science.

Fabrication and characterization of novel thermoresponsive emulsion gels and oleogels stabilizied by assembling nanofibrous from dual natural triterpenoid saponins

Novel thermoresponsive emulsion gels and oleogels were fabricated by assembling nanofibrous from natural triterpenoid Quillaja saponin (QS) and glycyrrhizic acid (GA). The viscoelasticity of QS-coated emulsion was observed to be remarkably improved by GA and thus obtain the advantages of excellent gelatinous, thermoresponsive and reversible manner due to the viscoelastic texture from GA nanofibrous as scaffolds in continuous phase. In the gelled emulsions, the phase transition of the GA fibrosis network structure upon heating and cooling was attributed to a thermal sensitivity, whereas interface-induced fibrosis assembly of amphiphilic QS endowed the formation of stable emulsion droplets. Then these emulsion gels were further used as an effective template to fabricate soft-solid oleogels with high oil content of 96%. These findings open up new opportunities for the use of all-natural and sustainable ingredients to develop smart soft materials for replace trans and saturated fats in food industry and other fields.

Effects of tea saponin on the foaming properties of pea protein

Plant proteins are becoming increasingly important for foam formation as an alternative to animal proteins. Consumers, however, are unsatisfied with the foaming properties of pea protein isolates. Recent research on proteins and surfactants has primarily concentrated on chemically synthesized surfactants. In this study, foams were prepared by complexing pea protein isolates with a natural small molecule surfactant tea saponin. This study investigates the mechanisms responsible for the formation and stability of foams prepared from pea protein isolates (PPIs) complexed with tea saponins. Analyses of foaming performance were carried out by analyzing the morphology of foam, foaming properties, foam's rheological properties, and the microstructure of the pea protein-tea saponin complex system. Compared to the pea protein isolate alone, the pea protein-tea saponin complex significantly improved foaming capacity and foaming stability. As shown by light microscopy analysis, the size of the foam decreased and became more homogeneous, probably because of the altered aggregate state of the protein. In this study, natural surfactants and mixtures of plant proteins are studied in order to better understand their properties. The mixed system has excellent prospects for application in the industries related to foam.

Bedaquiline fumarate microemulsion: formulation optimization, rheological characterization and in vitro studies

Aim: Bedaquiline fumarate (BQF), an antitubercular drug, shows limited bioavailability due to solubility-limited intestinal absorption. In this research, the authors formulated a BQF-loaded microemulsion to improve BQF's oral bioavailability. Methods: Microemulsion was prepared by a spontaneous emulsification method and evaluated for thermodynamic stability, size, dispersibility, transmittance, rheology, microrheology, drug release, cytotoxicity and cellular uptake. Results: Microemulsion showed an average globule size of 26.50 ± 6.29 nm with spherical geometry and revealed gel-sol-gel behavior in microrheological studies. Cytotoxicity and cell uptake studies in Caco-2 cells showed that BQF microemulsion was cytocompatible at the highest concentration of 500 μg/ml with significantly higher cellular uptake than control. Conclusion: The present study indicates that BQF microemulsion could be explored further for effective treatment of multidrug-resistant tuberculosis.

Comparison between Quinoa and Quillaja saponins in the Formation, Stability and Digestibility of Astaxanthin-Canola Oil Emulsions

Saponins from Quillaja saponaria and Chenopodium quinoa were evaluated as natural emulsifiers in the formation of astaxanthin enriched canola oil emulsions. The aim of this study was to define the processing conditions for developing emulsions and to evaluate their physical stability against environmental conditions: pH (2–10), temperature (20–50 °C), ionic strength (0–500 mM NaCl), and storage (35 days at 25 °C), as well as their performance in an in vitro digestion model. The emulsions were characterized, evaluating their mean particle size, polydispersity index (PDI), and zeta potential. Oil-in-water (O/W) emulsions were effectively produced using 1% oil phase and 1% emulsifier (saponins). Emulsions were stable over a wide range of pH values (4–10), but exhibited particle aggregation at lower pH, salt conditions, and high temperatures. The emulsion stability index (ESI) remained above 80% after 35 days of storage. The results of our study suggest that saponins can be an effective alternative to synthetic emulsifiers.

Saponins as Natural Emulsifiers for Nanoemulsions

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.

Physicochemical properties of saponin containing Acanthophyllum laxiusculum extract: example application in foam stability and qualitative parameters for malt beverage industry

Aqueous Extract of Acanthophyllum laxiusculum root (AE) exhibited remarkable foaming profile, emulsification properties and antifungal activity due to the presence of high concentration of total saponins. Total phenolic compounds, another main component, accounted for the AE antioxidant activity. Spray drying of AE, as a thermal process, did not affect the foaming indices of A. laxiusculum Spray-dried Extract (SE) and is a recommended alternate for convenient application in food industry. Addition of SE to the malt extract at accepted levels of total saponin daily intake (below 50 mg/kg) showed positive attribution of malt and carbonation on the foaming quality of SE. Meanwhile, antioxidant activity of commercial malt beverage was enhanced by addition of phenolic compounds containing SE. The 20-60% antifungal inhibitory ratio of the SE developed here is within the applied range of total saponin that supports its application to inhibit the growth of Saccharomyces cerevisiae after malt beverage production. The bitter taste of SE was not sensed in malt beverage at 30 mg/kg total saponin content and suggested A. laxiusculum root extract as a natural additive in malt industry.

Recent Advances and Applications of Plant-Based Bioactive Saponins in Colloidal Multiphase Food Systems

The naturally occurring saponins exhibit remarkable interfacial activity and also possess many biological activities linking to human health benefits, which make them particularly attractive as bifunctional building blocks for formulation of colloidal multiphase food systems. This review focuses on two commonly used food-grade saponins, Quillaja saponins (QS) and glycyrrhizic acid (GA), with the aim of clarifying the relationship between the structural features of saponin molecules and their subsequent self-assembly and interfacial properties. The recent applications of these two saponins in various colloidal multiphase systems, including liquid emulsions, gel emulsions, aqueous foams and complex emulsion foams, are then discussed. A particular emphasis is on the unique use of GA and GA nanofibrils as sole stabilizers for fabricating various multiphase food systems with many advanced qualities including simplicity, ultrastability, stimulability, structural viscoelasticity and processability. These natural saponin and saponin-based colloids are expected to be used as sustainable, plant-based ingredients for designing future foods, cosmetics and pharmaceuticals.

Effect of Cosurfactant on Structure and Properties of Polymerized High Internal Phase Emulsions (PolyHIPEs)

Porous polymerized high internal phase emulsion (polyHIPE) monoliths are synthesized by using Span 80 with different cosurfactants. The results reveal that the void size can be reduced by employing cosurfactants, except for Tween 20. Furthermore, the openness of polyHIPEs changes by using different cosurfactants or by varying their concentration. To further investigate the effect of cosurfactants, we perform rheology measurements on the interface of the aqueous and oil phase. This study demonstrates the important role of interfacial elasticity in the successful preparation of polyHIPEs with different morphologies. Additionally, this study suggests that the increase in interfacial elasticity hinders the formation of interconnections between pores, known as windows. Finally, the compression test is performed to investigate the effect of the pore structure on the mechanical properties.

Dual CO2 Responsiveness of an Oil-In-Water Emulsion by Using Sodium Oleate and Water-Soluble Tertiary Amines

Two kinds of water-soluble tertiary amines (TAs), triethylamine (TEA, monoamine), and tetramethyltrimethylenediamine (TMA, diamine) were introduced into a NaOA stable oil-water (O/W) emulsion, respectively, and their dual reactivity to carbon dioxide was studied. TA was converted into bicarbonate after bubbling of CO₂, which induced the increase of ionic strength of the aqueous phase, and formed ion pair with NaOA through electrostatic interaction. NaOA itself can also be protonated into oleic acid, which can be reverently deprotonated by alternating bubbles of CO₂ at 25 °C and N₂ at 50 °C, thus affecting the stability and demulsification process of the emulsion. In order to demonstrate TA's and NaOA's synergistic effect on CO₂ responsiveness, gas chromatography-mass spectrometry, ζ potential, electrical conductivity, pH value, ¹H nuclear magnetic resonance, morphological evolution, and interfacial tension were used to study the contributions of the single component and two components of NaOA, TEA, and TMA to emulsion stability and CO₂ responsiveness, respectively. Combined with the composition distribution under different pH conditions, it was further proved that TAs had an effect on the stability and CO₂ responsiveness of the NaOA emulsion.

Mixing Natural and Synthetic Surfactants: Co-Adsorption of Triterpenoid Saponins and Sodium Dodecyl Sulfate at the Air-Water Interface

Saponins are highly surface active glycosides, derived from a wide range of plant species. Their ability to produce stable foams and emulsions has stimulated their applications in beverages, foods, and cosmetics. To explore a wider range of potential applications, their surface mixing properties with conventional surfactants have been investigated. The competitive adsorption of the triterpenoid saponin escin with an anionic surfactant sodium dodecyl sulfate, SDS, at the air-water interface has been studied by neutron reflectivity, NR, and surface tension. The NR measurements, at concentrations above the mixed critical micelle concentration, demonstrate the impact of the relative surface activities of the two components. The surface mixing is highly nonideal and can be described quantitatively by the pseudophase approximation with the inclusion of the quadratic and cubic terms in the excess free energy of mixing. Hence, the surface mixing is highly asymmetrical and reflects both the electrostatic and steric contributions to the intermolecular interactions. The relative importance of the steric contribution is reinforced by the observation that the micelle mixing is even more nonideal than the surface mixing. The mixing properties result in the surface adsorption being largely dominated by the SDS over the composition and concentration range explored. The results and their interpretation provide an important insight into the wider potential for mixing saponins with more conventional surfactants.

Formation and stability of emulsions stabilized by Quillaja saponin-egg lecithin mixtures

Knowledge of binary emulsifiers' influence on the formation and stability of emulsion-based products is still limited. The aim of this study was to investigate the emulsifying properties of Quillaja saponin-egg lecithin mixtures at different concentration ratios (r = 5:0, 4:1, 3:2, 2:3, 1:4, and 0:5) with total emulsifier concentration set to 0.5% or 1.0% (w/w). For this, oil-in-water emulsions (10% oil, pH 7) were prepared via high-pressure homogenization. Furthermore, emulsion stability against different environmental stresses was tested. All the binary emulsifier mixtures formed submicron sized emulsions upon homogenization. The most stable emulsions among the mixed emulsifiers were obtained at low Quillaja saponin concentration at r = 1:4 that showed similar physical stability over time to emulsions stabilized by Quillaja saponins and egg lecithin alone. The data suggested that the mixtures of Quillaja saponins and egg lecithins built mixed interfacial layers that were prone to changes over time. Emulsions stabilized by the binary mixtures were in general less stable against changes in pH and ionic strength than the emulsions stabilized by the individual emulsifiers. An exception were the emulsions at r = 1:4 that showed improved stability at pH 2 over the phase separated Quillaja saponin-stabilized emulsions at the same pH. Moreover, all the emulsions were heat stable up to 90 °C. On the other hand, none of the emulsions were stable upon freeze-thawing. These results increase our understanding of technofunctionality of binary emulsifier systems. PRACTICAL APPLICATION: Food-grade and natural emulsifier mixtures composed of Quillaja saponins and egg lecithin may be used in selected emulsion-based food or personal care product applications to replace synthetic surfactants due to issues with consumer acceptance and regulatory restrictions.

Formulation and Optimization of Nanoemulsions Using the Natural Surfactant Saponin from Quillaja Bark

Replacing synthetic surfactants by natural alternatives when formulating nanoemulsions has gained attention as a sustainable approach. In this context, nanoemulsions based on sweet almond oil and stabilized by saponin from Quillaja bark with glycerol as cosurfactant were prepared by the high-pressure homogenization method. The effects of oil/water (O/W) ratio, total surfactant amount, and saponin/glycerol ratio on their stability were analyzed. The formation and stabilization of the oil-in-water nanoemulsions were analyzed through the evaluation of stability over time, pH, zeta potential, and particle size distribution analysis. Moreover, a design of experiments was performed to assess the most suitable composition based on particle size and stability parameters. The prepared nanoemulsions are, in general, highly stable over time, showing zeta potential values lower than −40 mV, a slight acid behavior due to the character of the components, and particle size (in volume) in the range of 1.1 to 4.3 µm. Response surface methodology revealed that formulations using an O/W ratio of 10/90 and 1.5 wt% surfactant resulted in lower particle sizes and zeta potential, presenting higher stability. The use of glycerol did not positively affect the formulations, which reinforces the suitability of preparing highly stable nanoemulsions based on natural surfactants such as saponins.

Interaction between soyasaponin and soy β-conglycinin or glycinin: Air-water interfacial behavior and foaming property of their mixtures

The interaction between soyasaponin and soy β-conglycinin (7S) or glycinin (11S), adsorption of their mixtures at air-water interface, and foaming properties of the mixed system were investigated in this study. Fluorescence spectroscopy results showed that there was a weak binding of soyasaponin with 7S or 11S in bulk solutions, leading to the conformational changes of protein by nonspecific hydrophobic interactions. Dynamic surface properties of soyasaponin-7S/11S mixtures indicated that the composite layers formed via their weak interactions due to the synergy of reducing surface tension and the plateau of elasticity at the interface. Most mixtures represented high foam forming ability and stability except 0.2 % soyasaponin mixture, which could be a consequence that the surface behavior was dominated by soyasaponin under this concentration, and low surface elasticity lead to a less stable interfacial film. Overall, foamability of soyasaponin-7S mixtures were better than 11S ones. All data of this work was helpful to understand air-water behaviors of soyasaponin-7S/11S mixtures. This mixed system has shown good potential for further foam related industrial applications.

Adsorption properties of plant based bio-surfactants: Insights from neutron scattering techniques

There is an increasing interest in biosustainable surfactants and surface active proteins for a range of applications, in home and personal care products, cosmetics, pharmaceuticals, and food and drink formulations. This review focuses on two plant derived biosurfactants, the surface active glycoside, saponin, and the surface active globular protein, hydrophobin. A particular emphasis in the review is on the role of neutron reflectivity in probing the adsorption, structure of the adsorbed layer, and their mixing at the interface with a range of more conventional surfactants and proteins.

Environmental fungi and bacteria facilitate lecithin decomposition and the transformation of phosphorus to apatite

Organophosphorus compounds (OP) are stable P source in nature, and can increase eutrophication risk in waterbodies. Lecithin was the most difficult OP to be broken down. In this study, two typical phosphate-solubilizing microorganisms, Aspergillus niger and Acinetobacter sp., were applied to evaluate their ability to decompose both inorganic phosphates and lecithin. A. niger and Acinetobacter sp. could solubilize calcium phosphates by secreting various organic acids, e.g., oxalic and formic acids. The fungus, A. niger, shows significantly higher ability of solubilizing these inorganic phosphates than Acinetobacter sp., primarily due to its secretion of abundant oxalic acid. However, the bacterium, Acinetobacter sp., could secrete more acid phosphatase than A. niger for lecithin decomposition, i.e., 9300 vs. 8500 μmol L-1 h-1. Moreover, after addition of CaCl2, the released P from lecithin was transformed to stable chlorapatite in the medium. To the contrast, Ca cations inclined to form calcium oxalate (rather than stable phosphate mineral) after the incubation of A. niger, as it induced relatively acidic environment after breaking down lecithin. Therefore, this work sheds light on the bright future of applying bacteria and Ca cations in OP pollutant management.

Foamy matters: an update on Quillaja saponins and their use as immunoadjuvants

Immunoadjuvant Quillaja spp. tree saponins stimulate both cellular and humoral responses, significantly widening vaccine target pathogen spectra. Host toxicity of specific saponins, fractions and extracts may be rather low and further reduced using lipid-based delivery systems. Saponins contain a hydrophobic central aglycone decorated with several sugar residues, posing a challenge for viable chemical synthesis. These, however, may provide simpler analogs. Saponin chemistry affords characteristic interactions with cell membranes, which are essential for its mechanism of action. Natural sources include Quillaja saponaria barks and, more recently, Quillaja brasiliensis leaves. Sustainable large-scale supply can use young plants grown in clonal gardens and elicitation treatments. Quillaja genomic studies will most likely buttress future synthetic biology-based saponin production efforts.

Quillaja Saponin Characteristics and Functional Properties

Consumer concerns about synthetically derived food additives have increased current research efforts to find naturally occurring alternatives. This review focuses on a group of natural surfactants, the Quillaja saponins, that can be extracted from the Quillaja saponaria Molina tree. Quillaja saponins are triterpenoid saponins comprising a hydrophobic quillaic acid backbone and hydrophilic sugar moieties. Commercially available Quillaja saponin products and their composition and properties are described, and the technofunctionality of Quillaja saponins in a variety of food, cosmetic, and pharmaceutical product applications is discussed. These applications make use of the biological and interfacial activities of Quillaja saponins and their ability to form and stabilize colloidal structures such as emulsions, foams, crystallized lipid particles, heteroaggregates, and micelles. Further emphasis is given to the complexation and functional properties of Quillaja saponins with other cosurfactants to create mixed surfactant systems, an approach that has the potential to facilitate new interfacial structures and novel functionalities.

Emulsifying properties of water-soluble proteins extracted from the microalgae Chlorella sorokiniana and Phaeodactylum tricornutum

This study investigated the formation and stability of emulsions with lyophilized water-soluble protein extracts from two different microalgae species. Lyophilized soluble protein extracts from Chlorella sorokiniana and Phaeodactylum tricornutum with a protein content of 39.2 and 37.2 wt%, respectively, were used. Drop-shape analysis showed them to have considerable interfacial activity at the oil-water interface. The application in emulsions, prepared by high-pressure homogenization (1000 bar, 3 passes, 5.0 wt% oil) further revealed that a concentration of 1.0 wt% soluble protein from Chlorella sorokiniana was sufficient to manufacture an emulsion with a monomodal droplet size distribution and a small volume based mean particle diameter (d43 = 232 ± 22 nm). Emulsions remained stable throughout 7 days of storage (d43,7d = 265 ± 4 nm). In contrast, 3.7 wt% of the respective proteins from Phaeodactylum tricornutum were needed to obtain a stable emulsion (d43 = 334 ± 12 nm and d43,7d = 325 ± 8 nm). Emulsions prepared with both algae fractions showed unusually high salt stabilities up to 500 mM of sodium chloride, with no appreciable changes in volume based mean particle diameter, appearance, or microstructure. Furthermore, model emulsions with soluble lyophilized proteins from Chlorella sorokiniana had a very high stability toward changes in pH (pH ≥ 5), whereas soluble proteins of Phaeodactylum tricornutum showed only a moderate pH stability with the smallest volume based particle size at pH 7.