Interfacial Properties of Saponin Extracts and Their Impact on Foam Characteristics

Rheological properties, microstructure, and encapsulation efficiency of inulin-type dietary fiber-based gelled emulsions at different concentrations

Gelled emulsion systems offer promising matrices for encapsulating bioactive compounds, enhancing stability, bioavailability, and controlled release. Incorporating inulin-type dietary fibers into emulsion-filled gels can innovate food products. This study explored the impact of inulin concentration (0-15 % w/w) on visual aspect, microstructure, particle size distribution, creaming stability, rheological behavior, and encapsulation efficiency of emulsions and gelled emulsions with clove bud oil rich in eugenol. Regardless of inulin concentration, systems exhibited evenly distributed small oil droplets, ensuring good creaming stability. Emulsions with 10-15 % inulin formed gels upon natural cooling to approximately 30 °C. Viscoelastic properties varied with inulin concentration, attributed to increased polymer chain approximation and mobility. Higher inulin content decreased the transition temperature (66 °C, 56 °C, and 54 °C for 10 %, 12.5 %, and 15 % inulin, respectively). While inulin did not enhance creaming stability, it acted as a physical barrier, improving encapsulation efficiency of eugenol to nearly 100 %. Inulin-based emulsion-filled gels offer potential for functional food development, enriching nutritional value and health benefits.

Plant-derived saponins and their prospective for cosmetic and personal care products

Plants are industrially cultivated and processed serving for specified sectors for human consumptions including cosmetic and personal care products. Where, the consumers' awareness towards sustainability are increasing year by year. Among which, those of the materials derived from the plants produced with good agricultural and manufacturing practices abided with bio-circular-green economy theme, are of eminence. This perspective is in line with the researchers' bioprospective onto natural products. Special attention sheds on saponins, the biosurfactants that will not cause detrimental effects on the environment. Which, plants are regarded as the sustainable sources of these cosmetic substances. However, among tremendous plants that have been continuously explored upon their potential applications. Most of the studies focus on preparation of the saponins and biological activities. Surprisingly, those that are abided with the list published in the European Commission (CosIng) that are of crucially for cosmetic regulation are insufficiently demonstrated, which burden their applications in the sector. This context summarizes the industrial crops that are registered as plant saponin in the CosIng database. Those that are insufficiently exploited on the information required for cosmetic formulations are therefore encouraged to be examined. In addition, multidirectional cosmetic beneficials of the filled plants saponin would be encouraged to be explored. These plants will be properly knowledge managed for their sustainable utilizations as the bio-based materials promising for cosmetic and personal care industrial perspectives.

Influence of Solvent Polarity on Crocin Content and Surface Properties of Saffron (Crocus sativus L.) Extracts

The saffron composition is being widely studied for authenticity and traceability, but very few works have been carried out to investigate the relationship between the chemical and physico-chemical properties of saffron solutes and their technological functionality in colloidal systems. This study aims at evaluating the surface properties of saffron extracts obtained using solvents of different polarities to achieve extracts with different compositions in terms of the pattern and content of polar and medium polarity crocins. The air-water surface was evaluated alone and in the presence of Tween 20 at different surfactant-extract ratios. Saffron extracts were able to decrease the surface tension of the aqueous phase, indicating the presence of surface-active compounds. In the mixed saffron extract-Tween 20 systems, competitive adsorption at the air-water interface occurred when the surfactant was present at a low concentration, while at concentrations higher than the CMC, Tween 20 hindered the adsorption of the extract surface-active compounds. The results highlight the interesting technological functionality of saffron extracts for applications in colloidal systems. To better exploit their use in the design and development of formulated foods, nutraceutics and pharma products, further studies are needed to unravel the relationship between the composition of saffron extracts and corresponding surface activity.

Saponin Molecules from Quinoa Residues: Exploring Their Surfactant, Emulsifying, and Detergent Properties

The indiscriminate use of synthetic surfactants, despite their desirable properties, poses significant environmental risks to ecosystems. This study explores saponins extracted from quinoa (Chenopodium quinoa) residues as a sustainable alternative. Saponin extract (SE) with 42% purity, obtained through hydrodynamic cavitation and membrane technology, was analyzed to determine its techno-functional properties. The critical micelle concentration (CMC) was 1.2 g/L, reducing the surface tension (ST) from 72.0 mN/m to 50.0 mN/m. The effects of temperature (30-90 °C), pH (2-12), and salinity (10,000-150,000 ppm NaCl) on ST and the emulsification index (EI) were assessed using a Box-Behnken design. Optimized conditions yielded an ST of 49.02 mN/m and an EI of 63%. Given these characteristics, SE was evaluated as a detergent across diverse swatches. This study showcases the attributes of quinoa-derived saponins, highlighting their potential for eco-friendly detergent applications.

Classification of surfactants and admixtures for producing stable aqueous foam

Surfactants and foam have captured the interest of researchers worldwide due to their unique behavior of surface activity, the dynamic nature of foam formation, and simultaneous destruction. The present review focuses on the surfactants' classification, surfactant-solvent interaction, foam formation, characteristics, and a range of admixtures to enhance the foam performance. Although surfactants have been researched and developed for decades, recently, their sustainability has been given special attention. One such aspect is the development of green foaming agents from natural and renewable sources and assessing their suitability for different applications. Further, widely researched parameters are the type of surfactant, surfactant concentration, surfactant-solvent interaction, and foam production method on the foamability of a surfactant solution and related foam characteristics, including stability and texture. However, still, there is no rule to predict the best foam. Another vital concern is the non-standardization of foam assessment methods across industries and regions. Recently, research has progressed in identifying suitable admixtures for foam performance enhancement and utilizing them to produce stable foams for application in enhanced oil recovery, drug delivery, and manufacturing of aerated food products and foamed concrete. Although foam stabilization using various admixtures has been recognized well in the literature, the underlying mechanism requires further research. The interaction of surfactant and admixtures in solution is complicated and requires more research.

Foam and fluid properties of purified saponins and non-purified water extracts from Camellia oleifera cake (by-product)

The physicochemical and foam properties of non-purified water extracts (WE) and purified tea saponins (TS) from Camellia oleifera cake (byproduct) were compared. WE showed different fluid properties at equal saponin concentrations (1.0 wt%) compared to TS. Particularly, it exhibited limited micelle size (average 434.1 nm), effective viscosity (0.15 Pa·s), and surface tension (43.9 mN/m) independently of pH. Moreover, the foam properties of WE were comparable to TS and better than sodium caseinate, especially foam stability. WE foam was more stable than TS foam under pH (3-7) and heating (40-80 °C). In the presence of NaCl, sucrose, and ethanol (5-20 wt%), WE and TS were effective and had similar foam behavior. Low concentrations of sucrose (<10 wt%)/ethanol (<20 wt%) significantly increased the foam capacity, while ethanol over 30 wt% was unfavorable. WE/TS foam contributes significantly to the desired physicochemical and sensory attributes (taste, texture, and appearance) of foods.

Bioactive foamulsion gels: a unique structure prepared with gellan gum and Acanthophyllum glandulosum extract

BACKGROUND

Foamulsions have become increasingly popular in the food industry due to their ability to enhance the textural, sensory and health-promoting properties of food products. This study was therefore aimed to design and prepare a novel gelled structure, foamulsion gel containing 0-600 g L-1 oil, with gellan gum (GG; 7, 10 and 13 g L-1) and saponin-rich antioxidant Acanthophyllum glandulosum extract (AGE; 2, 6 and 10 g L-1).

RESULTS

The interaction between components was confirmed by infrared spectroscopy. The overrun and porosity of the foamulsion gels increased with antioxidant AGE (1.30 times) and reduced with oil (up to ca 70% and 30%, respectively) and GG levels. The systems were highly stable, and no water or oil was released during the physical stability experiments. Microscopic images showed that the size of air cells was significantly larger than that of oil droplets. The foamulsion gels based on 13 g L-1 GG and 10 g L-1 AGE had markedly higher elastic (G') and viscous (G'') moduli than other samples, and exhibited an elastic and solid-like behavior (G' > G''). The highest gel firmness was found in oil-free sample, and the presence of oil resulted in a lower firmness induced by the larger size and lubrication effect of oil droplets.

CONCLUSION

As a result, the interactions between AGE, GG and oil could lead to the creation of new aerated structures known as bioactive foamulsion gels. These gels exhibit excellent foamability, stability and viscoelasticity and may find applications in the development of novel, healthy and low-calorie aerated foods. © 2024 Society of Chemical Industry.

Applications of Saponin Extract from Asparagus Roots as Functional Ingredient

When replanting an asparagus field, the roots of the previous crop are crushed and incorporated into the soil, creating problems of autotoxicity and fungal infections. Asparagus roots can be considered as a valuable byproduct, since they are very rich in saponins (3-6%), compounds currently considered as bio-emulsifiers. The objective is to evaluate the emulsifying and foaming capacity of a saponin extract from asparagus roots (ARS) and compare it with other commercial extracts. ARS was obtained using a process patented by our research group. The results have shown that ARS has activity similar to Quillaja extract. Its critical micellar concentration falls between that of Quillaja and Tribulus extracts (0.064, 0.043, and 0.094 g/100 mL, respectively). Both emulsifying and foaming activities are affected by pH, salt, and sucrose to a similar extent as the other extracts. Additionally, it has demonstrated an inhibitory effect on pancreatic lipase, which is even better than the other two studied extracts, as indicated by its IC50 value (0.7887, 1.6366, and 2.0107 mg/mL for asparagus, Quillaja, and Tribulus, respectively). These results suggest that ARS could serve as a natural emulsifying/foaming agent for healthier and safer food products and as a potential aid in treatments for obesity and hyperlipidemia.

Emulsification Properties of Garlic Aqueous Extract: Effect of Heat Treatment and pH Modification

Despite the broad research available in the literature dealing with garlic health benefits, little information is found regarding the functional properties of garlic components. The aim of this study was to evaluate the emulsification properties of garlic water-soluble compounds (GWSC), encompassing proteins, saponins, and carbohydrates, after heat treatment (10 min at 95 °C) or pH adjustments (2.5, 3.5, and 7.8). After the various treatments, the extracts were used as such or filtrated (0.45 µm), and 10% soybean oil-in-water emulsions were prepared using low (0.48%) or high (6.55% wt/wt) extract concentrations. Results showed that whereas at low GWSC concentrations, both heating and acidifying resulted in the formation of bigger oil droplet sizes (i.e., from d32 = 0.36 µm using unmodified extract to d32 = 7-22 µm at pH 2.5 with or without extract filtration), the effects were opposite at the highest GWSC concentration. In the latter, heat treatment clearly reduced the droplet size as observed from the micrographs as well as the degree of creaming, though the occurrence of depletion and/or bridging flocculation was still strong. The acidification of the extract at this high GWSC concentration significantly reduced the droplet size, as observed from the micrographs; however, a strong flocculation was observed. Removal of protein aggregates, and possibly also saponin micelles, from the extract resulted in an obvious increase in emulsion droplet size. This research brings valuable insights on this study and utilisation of novel natural food emulsifiers from plant sources.

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.

Characterization of saponins from the leaves and stem bark of Jatropha curcas L. for surface-active properties

In this study, saponins extracted from leaves and stem bark of Jatropha curcas L. were investigated for surface-active properties. Conductivity and surface tension measurements revealed the micellar character of J. curcas saponin, with the average CMC, determined to be 0.50 g/L and 0.75 g/L for leaf and stem bark saponin, respectively. Stem bark saponin reduced the surface tension of water to a greater extent (γCMC= 37.65 mN/m) compared to leaf saponin (γCMC= 49.27 mN/m) indicating its efficient surface activity and potential detergency. pH measurement confirmed the weakly acidic nature of saponin with a pH value lying slightly below the range suitable for hair and skin. Stem bark saponin showed better cleaning ability, foaming ability and foam stability than leaf saponin, due to a sufficient reduction in the surface tension of water. The results obtained suggest that the saponin extracted from both the leaves and stem bark of J. curcas can be used as environmentally friendly alternatives to synthetic surfactants.

Valorisation through Lactic Fermentation of Industrial Wastewaters from a Bean Blanching Treatment

In recent years, scientific research and industries have been focusing on the application of biological treatments aimed at imparting functional properties to waste products from food industries according to the principles on which the circular economy model is based, namely, the recovery, valorisation, and reuse of wastes. This work aimed at exploring the possibility of valorising waters from the blanching process of dried navy beans through lactic acid fermentation using Lacticaseibacillus paracasei CBA L74 as a starter. Two samples at different solid concentrations (0.75 °Bx and 1.25 °Bx) were fermented, and, in both cases, a bacterial load of 8 Logs and a lactic acid concentration of approximately 1.3 g/L were reached, despite the lack of nutrients. An unusual pH trend, characterised by an initial decrease and unexpected final rise, was observed during the fermentation of both samples: simultaneously, an increase in protein content was observed, suggesting that the proteolytic action of the microorganism could be responsible for the release of pH-increasing substances. In both cases, a slight increase in total polyphenols (approximately 23.3–33.72%) and flavonoids (approximately 42.3–52%) due to fermentation was observed, with a corresponding improvement in antioxidant capacity (approximately 25.32–37.72%). A significant increase in saponin concentration was determined for the most concentrated blanching water (from 2.87 ± 0.28 to 6.68 ± 0.69 mgOAE/mL), leading to an improvement in foaming properties and an enhanced capacity to produce stable emulsions. The obtained results confirmed the possibility of reducing water consumption from blanching operations, as well as finding valorisation opportunities for this side stream through a safe and inexpensive fermentation treatment.

Saponin Biosynthesis in Pulses

Pulses are a group of leguminous crops that are harvested solely for their dry seeds. As the demand for plant-based proteins grows, pulses are becoming important food crops worldwide. In addition to being a rich source of nutrients, pulses also contain saponins that are traditionally considered anti-nutrients, and impart bitterness and astringency. Saponins are plant secondary metabolites with great structural and functional diversity. Given their diverse functional properties and biological activities, both undesirable and beneficial, saponins have received growing attention. It can be expected that redirecting metabolic fluxes to control the saponin levels and produce desired saponins would be an effective approach to improve the nutritional and sensory quality of the pulses. However, little effort has been made toward understanding saponin biosynthesis in pulses, and, thus there exist sizable knowledge gaps regarding its pathway and regulatory network. In this paper, we summarize the research progress made on saponin biosynthesis in pulses. Additionally, phylogenetic relationships of putative biosynthetic enzymes among multiple pulse species provide a glimpse of the evolutionary routes and functional diversification of saponin biosynthetic enzymes. The review will help us to advance our understanding of saponin biosynthesis and aid in the development of molecular and biotechnological tools for the systematic optimization of metabolic fluxes, in order to produce the desired saponins in pulses.

Physicochemical and sensory properties of malt beverage containing sugar beet saponins

Aqueous two-phase system (ATPS) composed of polyethylene glycol (PEG) and K2HPO4 solutions was used to extract saponin from sugar beet root. Extraction yield, purity and foam capacity of saponin were optimized according to response surface methodology (RSM). Analysis of liquid chromatography-mass spectrometry (LC-MS) showed that purified saponins were composed of hederagenin, akebonoic acid and oleanolic acid. Addition of 0.02 g sugar beet root saponin to one liter of malt beverage caused a considerable increase in foam volume and stability compared to malt beverage samples containing 0.1 g/L propylene glycol alginate (PGA). Malt beverages containing saponin showed higher turbidity, bitterness and overall sensory acceptance. Moreover, no significant changes in malt drink pH and °Brix were observed due to saponin addition. Adding lemon flavor caused a decrease in foam stability and sensory acceptance of malt beverage containing saponin compared to PGA containing ones. Less saponin content is suggested for flavored malt drinks.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-022-05517-x.

Synergy in Aqueous Systems Containing Bioactive Ingredients of Natural Origin: Saponin/Pectin Mixtures

Biocompatible and biodegradable ingredients of natural origin are widely used in the design of foam and emulsion systems with various technological applications in the food, cosmetics and pharmaceutical industries. The determination of the precise composition of aqueous solution formulations is a key issue for the achievement of environmentally-friendly disperse systems with controllable properties and reasonable stability. The present work is focused on the investigation of synergistic interactions in aqueous systems containing Quillaja saponins and Apple pectins. Profile analysis tensiometer (PAT-1) is applied to study the surface tension and surface dilational rheology of the adsorption layers at the air/solution interface. The properties and the foam films (drainage kinetics, film thickness, disjoining pressure isotherm, critical pressure of rupture) are investigated using the thin-liquid-film (TLF) microinterferometric method of Scheludko–Exerowa and the TLF-pressure-balance technique (TLF-PBT). The results demonstrate that the structure and stability performance of the complex aqueous solutions can be finely tuned by changing the ratio of the bioactive ingredients. The attained experimental data evidence that the most pronounced synergy effect is registered at a specific saponin:pectin ratio. The obtained information is essential for the further development of aqueous solution formulations intended to achieve stable foams based on mixtures of Quillaja saponins and Apple pectins in view of future industrial, pharmaceutical and biomedical applications.

Extraction of Oils and Phytochemicals from Camellia oleifera Seeds: Trends, Challenges, and Innovations

Camellia seed oil, extracted from the seeds of Camellia oleifera Abel., is popular in South China because of its high nutritive value and unique flavor. Nowadays, the traditional extraction methods of hot pressing extraction (HPE) and solvent extraction (SE) are contentious due to low product quality and high environmental impact. Innovative methods such as supercritical fluid extraction (SCFE) and aqueous extraction (AE) are proposed to overcome the pitfalls of the traditional methods. However, they are often limited to the laboratory or pilot scale due to economic or technical bottlenecks. Optimization of extraction processes indicates the challenges in finding the optimal balance between the yield and quality of oils and phytochemicals, as well as the environmental and economic impacts. This article aims to explore recent advances and innovations related to the extraction of oils and phytochemicals from camellia seeds, and it focuses on the pretreatment and extraction processes, as well as their complex effects on nutritional and sensory qualities. We hope this review will help readers to better understand the trends, challenges, and innovations associated with the camellia industry.

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.

Structure-function relationship of licorice (Glycyrrhiza glabra) root extract-xanthan/guar gum mixture in a high sugar content system

BACKGROUND

Foam-gels are one of the most important multicomponent-model systems in aerated confectionery, and an investigation of their microstructure is desirable. In this research, the structure-function relationship of xanthan gum/guar gum (XG/GG) and licorice (Glycyrrhiza glabra) root extract powder (LEP) was investigated in a high-sugar medium. Foam-gel systems were prepared at 4:10% to 8:20% ratios of LEP to biopolymer.

RESULTS

The results show that increasing the LEP content reduced both the melting point and enthalpy, probably due to higher overrun and weaker junctions. Boosting the XG/GG ratio led the enhancement of mechanical properties, whereas increasing the LEP concentration weakened all textural parameters, which could be due to the poor structure of the network in the presence of the foaming agent, increased moisture content and overrun. In the whipped mixture samples containing 10 g kg^-1 XG/GG, higher foaming capacity was observed. By increasing the level of biopolymers, smaller and more uniform air cells were formed according to a scanning electron microscopical study. At higher concentration of LEP, smaller bubbles and increased porosity were seen, which could be attributed to the availability of surfactant in the interfacial layer.

CONCLUSION

Maximum structural strength was achieved at a 4:20 ratio of LEP to XG/GG. In rheological experiments, pseudoplastic behavior was seen in all samples. Generally, this model system can be simulated for other herbal extracts containing natural surfactants such as saponins. Achieving a more detailed understanding of these structures and their interactions could help in formulating novel food products. © 2021 Society of Chemical 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.

Structure, Bioactivity and Analytical Methods for the Determination of Yucca Saponins

Yucca is one of the main sources of steroidal saponins, hence different extracts are commercialized for use as surfactant additives by beverage, animal feed, cosmetics or agricultural products. For a deeper understanding of the potential of the saponins that can be found in this genus, an exhaustive review of the structural characteristics, bioactivities and analytical methods that can be used with these compounds has been carried out, since there are no recent reviews on the matter. Thus, a total of 108 saponins from eight species of the genus Yucca have been described. Out of these, the bioactivity of 68 saponins derived from the isolation of Yucca or other genera has been evaluated. Regarding the evaluation and quality control of the saponins from this genus LC-MS technique is the most often used. Nevertheless, the development of methods for their routine analysis in commercial preparations are needed. Moreover, most of the studies found in the literature have been carried out on Y. schidigera extract, since is the most often used for commercial purposes. Only eight of the 50 species that belong to this genus have been studied, which clearly indicates that the identification of saponins present in Yucca genus is still an unresolved question.

Ethnochemometric of plants traditionally utilised as local detergents in the forest dependent culture

The purpose of this study is to access the existing awareness of nearly forgotten Thai detergent plants by the use of chemometrics tool. A Northern Thai forest dependent community was chosen as it played vital role on knowledge retaining of plant utilisations. For initial perception, ethnobotanical survey was conducted to determine usage of plants by the community. Then the utilised plant parts were screened for phytochemicals and their relationships with the defined cleansing terms (viz., shampoo, scrub, detergent, soap, scent and spiritual) were analysed by Principal Component Analysis (PCA). From the results, the most cited plants as known, used and found were Acacia concinna, Clitoria ternetea, Oryza sativa and Citrus hystrix. Biometric analyses advised that knowledge of detergent plant utilisation was well preserved at all age ranges and it was not variable with genders. Cluster analysis described that term 'spiritual' was not narrated with cleansing properties. For phytochemical analysis, plant extracts showed positive variable of bioactive ingredients and the main compounds in the extracts was saponins. These findings confirmed that the knowledge of indigenous plant utilisation was reserved by the forest dependent community and the information is beneficial toward local plant conservation movement.

Adsorption and self-assembly properties of the plant based biosurfactant, Glycyrrhizic acid

There is an increased interest in the use of natural surfactant as replacements for synthetic surfactants due to their biosustainable and biocompatible properties. A category of natural surfactants which are attracting much current interest is the triterpenoid saponins; surface active components found extensively in a wide range of plant species. A wide range of different saponin structures exist, depending upon the plant species they are extracted from; but regardless of the variation in structural details they are all highly surface active glycosides. Greater exploitation and application requires a characterisation and understanding of their basic adsorption and self-assembly properties.

HYPOTHESIS

Glycyrrhizic acid, extracted from Licorice root, is a monodesmosidic triterpenoid saponin. It is widely used in cosmetic and pharmaceutical applications due to its anti-inflammatory properties, and is an ingredient in foods as a sweetener additive. It has an additional attraction due to its gel forming properties at relatively low concentrations. Although it has attracted much recent attention, many of its basic surface active characteristics, adsorption and self-assembly, remain relatively unexplored. How the structure of the Glycyrrhizic acid saponin affects its surface active properties and the impact of gelation on these properties are important considerations, and to investigate these are the focus of the study.

EXPERIMENTS

In this paper the adsorption properties at the air-water interface and the self-assembly in solution have been investigated using by neutron reflectivity and small angle neutron scattering; in non-gelling and gelling conditions.

FINDINGS

The adsorption isotherm is determined in water and in the presence of gelling additives, and compared with the adsorption behaviour of other saponins. Gelation has minimal impact on the adsorption; apart from producing a rougher surface with a surface texture on a macroscopic length scale. Globular micelles are formed in aqueous solution with modest anisotropy, and are compared with the structure of other saponin micelles. The addition of gelling agents results in only minimal micelle growth, and the solutions remain isotropic under applied shear flow.

Aescin - a natural soap for the formation of lipid nanodiscs with tunable size

The saponin β-aescin from the seed extract of the horse chestnut tree Aesculus hippocastanum has demonstrated a beneficial role in clinical therapy which is in part related to its strong interaction with biological membranes. In this context the present work investigates the self-assembly of nm-sized discoidal lipid nanoparticles composed of β-aescin and the phospholipid 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC). The discoidal lipid nanoparticles reassemble from small discs into larger discs, ribbons and finally stacks of sheets upon heating from gel-phase to fluid phase DMPC. The morphological transition of the lipid nano-particles is mainly triggered by the phospholipid phase state change. The final morphology depends on the phospholipid-to-saponin ratio and the actual temperature. The study is conducted by small-angle X-ray scattering (SAXS) and transmission (TEM) and freeze fracture electron microscopy (FFEM) are used to cover larger length scales. Two different models, representing a disc and ribbon-like shape are applied to the SAXS data, evaluating possible geometries and molecular mixing of the nano-particles. The stacked sheets are analysed by the Caillé theory.

Usability of soapwort and horse chestnut saponin extracts as foaming agents in foam mat drying of pomegranate juice

BACKGROUND

This study evaluated the usability of saponin-rich extracts (soapwort and horse chestnut) as a foaming agent for foam mat drying of pomegranate juice.

RESULTS

According to the foaming and stabilization studies, the optimum conditions were determined as 0.4% of soapwort extract, 0.03% of carboxymethyl cellulose as a stabilizer, and 3 min of whipping time. The foams produced using these conditions were dried at different spreading thicknesses and drying temperatures. The results showed that the thicker spreading thicknesses provided a higher antioxidant activity. On the other hand, drying temperature had a significant effect on all measured parameters except moisture content and water activity. The higher drying temperature caused a greater colour change and a lower content of total phenolics, total monomeric anthocyanins, cyanidin-3-glucoside, and delphinidin-3-glucoside. On the other hand, a higher content of ascorbic acid and better antioxidant activity was determined in the samples dried at 70 °C.

CONCLUSION

According to the results obtained, spreading thickness of 2 mm and drying temperature of 70 °C were suggested for pomegranate juice powder production by foam mat drying. Overall, it was demonstrated that saponin-rich extracts are a good foaming agent alternative that provides foaming at very low concentrations and a product with high quality. © 2020 Society of Chemical Industry.

Physicochemical, functional and structural characteristics of grains, flour and protein isolates of Indian quinoa lines

The physicochemical and functional properties of grains, flour and protein isolates (QPI) from different quinoa lines were evaluated. Quinoa flour and protein isolates were characterised by high protein (14.1-15.4% and 78.7-86%, respectively) and phenolic content (419 to 655 mg GAE/100 g). Water and oil absorption capacity of QPI (2.0-3.6 g/g and 2.71-3.32 g/g, respectively) was significantly higher than quinoa flour (1.22 and 2.17 gand 0.9 and1.54 g, respectively). QPI showed desirable functional properties in terms of high foaming capacity (50.8 to 60.2%), foam stability (38.5 to 50.4%), protein solubility (30 and 53.3%), and emulsification index (EAI- 19.2-26.1 m²/g and ESI- 96.7-149.8 min, respectively). Digestibility of QPI ranged between 70.8 and 77.8% and was negatively correlated to random coils. Quinoa lines with higher grain density (GD) showed higher total phenol content (TPC) and WAC and lower FRSA and OAC. QPI with higher proportions of β-structure and random coils had enhanced protein surface activities leading to improved emulsification and foaming capabilities. Among the highly conserved polypeptides (PPs), variations were observed in accumulation of 53, 59 and 32 kDa PPs for grains and 33 and 21-24 kDa PPs for QPI.

Natural Surfactant Saponin from Tissue of Litsea glutinosa and Its Alternative Sustainable Production

In this research, we assessed the detergency properties along with chemical characteristic of the surfactant extracts from the most frequently cited detergent plants in Northern Thailand, namely, Sapindus rarak, Acacia concinna, and Litsea glutinosa. Moreover, as to provide the sustainable option for production of such valuable ingredients, plant tissue culture (PTC) as alternative method for industrial metabolite cultivation was also proposed herein. The results illustrated that detergent plant extracts showed moderate in foaming and detergency abilities compared with those of synthetic surfactant. The phytochemical analysis illustrated the positive detection of saponins in L. glutinosa plant extracts. The highest callus formation was found in L. glutinosa explant cultured with MS medium supplemented with 2.0 mg/L Indole-3-acetic acid (IAA). The callus extract was chemical elucidated using chromatography, which illustrated the presence of saponin similar to those from the crude leaf and Quillaja saponin extracts. Compact mass spectrometry confirmed that the surfactant was of the steroidal diagnostic type.

Molecularization of Foam-Active Saponins from Sugar Beet Side Streams (Beta vulgaris ssp. vulgaris var. altissima)

This work focuses on the isolation and characterization of saponins with a very low bitter intensity originating from sustainable plant materials, in particular the sugar beet pulp by-product stream. Via a concise foam activity screening of saponin-containing materials, which gives indications for their emulsifying ability, sugar beet root extract was selected and examined for low bitter saponins by means of activity guided fractionation. Individual saponins were isolated from sugar beet pulp, which was identified as the most convenient sugar beet saponin source. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis and one-dimensional (1D) and two-dimensional (2D) nuclear magnetic resonance (NMR) spectroscopy led to the unequivocal identification of the major, slightly bitter tasting compounds as a series of eight saponins. The complete assignment of ¹H and ¹³C NMR signals for several saponins was carried out for the first time. A small-scale foam activity assay was established and applied to a broad spectrum of the isolated and commercially available saponins. Additionally, orosensory recognition thresholds were determined. Not only high recognition thresholds were determined (thresholds >1000 μmol/L) but also fundamental information about the foaming behavior of mono- and bidesmosidic saponins was collected. The obtained results are relevant to the utilization of saponins from other plant materials or by-product streams and for the use of sugar beet saponins as food additives.

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.

Surface activity and foaming properties of saponin-rich plants extracts

Saponins are amphiphilic glycosidic secondary metabolites produced by numerous plants. So far only few of them have been thoroughly analyzed and even less have found industrial applications as biosurfactants. In this contribution we screen 45 plants from different families, reported to be rich in saponins, for their surface activity and foaming properties. For this purpose, the room-temperature aqueous extracts (macerates) from the alleged saponin-rich plant organs were prepared and spray-dried under the same conditions, in presence of sodium benzoate and potassium sorbate as preservatives and drying aids. For 15 selected plants, the extraction was also performed using hot water (decoction for 15 min) but high temperature in most cases deteriorated surface activity of the extracts. To our knowledge, for most of the extracts this is the first quantitative report on their surface activity. Among the tested plants, only 3 showed the ability to reduce surface tension of their solutions by more than 20 mN/m at 1% dry extract mass content. The adsorption layers forming spontaneously on the surface of these extracts showed a broad range of surface dilational rheology responses - from null to very high, with surface dilational elasticity modulus, E' in excess of 100 mN/m for 5 plants. In all cases the surface dilational response was dominated by the elastic contribution, typical for saponins and other biosurfactants. Almost all extracts showed the ability to froth, but only 32 could sustain the foam for more than 1 min (for 11 extracts the foams were stable during at least 10 min). In general, the ability to lower surface tension and to produce adsorbed layers with high surface elasticity did not correlate well with the ability to form and sustain the foam. Based on the overall characteristics, Saponaria officinalis L. (soapwort), Avena sativa L. (oat), Aesculus hippocastanum L. (horse chestnut), Chenopodium quinoa Willd. (quinoa), Vaccaria hispanica (Mill.) Rauschert (cowherb) and Glycine max (L.) Merr. (soybean) are proposed as the best potential sources of saponins for surfactant applications in natural cosmetic and household products.

Chemical Constituents, Biological Properties, and Uses of Tribulus terrestris: A Review

Tribulus terrestris L. (TT) (puncturevine) is a common weed that grows in many countries worldwide and in some places is considered as a noxious weed. The plant has been used in traditional Chinese and Indian medicines and is now considered as one of the most popular aphrodisiacs. It is known for its healing properties for sexual difficulties, impotence, and human and animal hormonal imbalance. It is also used as a sexual booster. Because of the plant’s active substances that can be used for curing sexual and other disorders, interest in it is increasing, and it is currently one of the most studied medicinal plants. The products and preparations manufactured from the aboveground plant parts are especially popular among athletes and people with health issues and diseases such as hormonal imbalance, sexual problems, heart problems, and various kidney and skin diseases. The aim of this review is a comprehensive and critical assessment of the scientific publications involving TT, with special reference to its chemical constituents and biological properties that may facilitate current understanding and future studies of this fascinating plant species. The objectives of this review were (1) to find knowledge gaps, (2) to discuss critically relevant publications and issues with materials and methods that may be prerequisites for contradictory results, and (3) to identify research and development areas. It was found that some of the studies on TT extracts as aphrodisiacs are controversial. A significant number of research publications claim that TT extracts and nutritional supplements containing TT improve muscle tone, have a common biostimulating effect, and improve spermogenesis. However, there are a growing number of publications that dispute these claims, as there are no empirical data on commonly accepted mechanisms of action. The main biologically active substances in TT are steroidal saponins, flavonoids, alkaloids, and lignan amides, the most studied being the steroidal saponins. Multiyear data on the metabolic profile of the species are generally lacking. There are a variety of methods used for extracting plant material, differences in methodologies and saponin analyses, and scientific instruments that were used. Lack of common standards could be a reason for differences in the pharmacological activity and composition of the TT preparations. Development of standard procedures and methods for collection of plant material and analyses are recommended. Selection and breeding efforts and agronomic studies of promising clones of TT would need to be conducted in order to develop TT as a new crop. This will provide consistency of supply and quality of the feedstock for the pharmaceutical industry and could provide a new cash crop for growers.

Surface properties and foamability of saponin and saponin-chitosan systems

In this work we investigate the surface properties and foamability of saponin and mixed saponin-chitosan solutions. These natural compounds are widely used in various cosmetic, pharmaceutical and food technologies because of their efficiency as bio-active components and their biodegradability. These compounds and their mixture were investigated versus the composition by surface tension and dilational rheology measurements and the respective foams analysed at the formation and during their entire time evolution. The results show that these systems present peculiarities relevant for their utilisation as foam stabilisers, such as strong amphiphilicity of saponin and high values of dilational viscoelasticity. The behaviour of foams has been interpreted on the basis of the adsorption properties at liquid-air interface and the interfacial rheology. Specifically, we found a remarkable effect of the chitosan on the long-time stability of foams. This has been explained considering the changes of the bulk properties induced by chitosan, which influence also the dynamics of the saponin adsorption. This work aims to contribute to the development of new formulations of biodegradable and biocompatible foams for industrial applications, where it is advantageous to reduce the use of synthetic surfactants in commercial products.

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.