Use of natural emulsifiers in model coffee creamers: Physical properties of quillaja saponin-stabilized emulsions

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.

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.

The science of plant-based foods: Constructing next-generation meat, fish, milk, and egg analogs

Consumers are increasingly demanding foods that are more ethical, sustainable and nutritious to improve the health of themselves and the planet. The food industry is currently undergoing a revolution, as both small and large companies pivot toward the creation of a new generation of plant-based products to meet this consumer demand. In particular, there is an emphasis on the production of plant-based foods that mimic those that omnivores are familiar with, such as meat, fish, egg, milk, and their products. The main challenge in this area is to simulate the desirable appearance, texture, flavor, mouthfeel, and functionality of these products using ingredients that are isolated entirely from botanical sources, such as proteins, carbohydrates, and lipids. The molecular, chemical, and physical properties of plant-derived ingredients are usually very different from those of animal-derived ones. It is therefore critical to understand the fundamental properties of plant-derived ingredients and how they can be assembled into structures resembling those found in animal products. This review article provides an overview of the current status of the scientific understanding of plant-based foods and highlights areas where further research is required. In particular, it focuses on the chemical, physical, and functional properties of plant-derived ingredients; the processing operations that can be used to convert these ingredients into food products; and, the science behind the formulation of vegan meat, fish, eggs, and milk alternatives.

Fabrication of oil-in-water emulsions as shelf-stable liquid non-dairy creamers: effects of homogenization pressure, oil type, and emulsifier concentration

BACKGROUND

The popularity of coffee, the second most consumed beverage in the world, contributes to the high demand for liquid non-dairy creamer (LNDC). In this study, palm olein emulsions (as LNDCs) were investigated as alternatives to the more common soybean oil-based LNDCs. LNDCs were prepared via different homogenization pressures (100-300 bar) using different types of oil (palm olein and soybean oil) and concentrations of DATEM emulsifier (5-20 g kg^-1 ).

RESULTS

Increases in homogenization pressure and emulsifier concentration were observed to have significant (P < 0.05) effects on the physicochemical properties (particle size, pH, and viscosity) of the LNDCs. Palm olein and soybean oil LNDCs prepared using 15 g kg^-1 and 10 g kg^-1 DATEM emulsifier, respectively, were determined to be the most stable (as observed throughout a 15-day storage period at ambient temperature of 28 ± 2 °C), with properties closest to those of a commercial LNDC. When added to black coffee, both LNDCs displayed a good whitening effect by increasing the L* value from 26.73 ± 0.16 (black coffee) to ≥40.82 ± 0.56 (black coffee + LNDCs). Sensory evaluation showed that there were no significant (P > 0.05) differences between the prepared and commercial LNDCs in terms of their color, appearance, and overall acceptability.

CONCLUSION

Shelf-stable LNDCs with qualities comparable to commercial LNDC were successfully fabricated. Valuable insights into the effects of homogenization pressure, oil type, and emulsifier concentration, as well as functionality and consumer acceptance of the LNDCs when added into black coffee, were obtained. © 2020 Society of Chemical Industry.

Standardized methods for testing the quality attributes of plant-based foods: Milk and cream alternatives

The food industry is creating a diverse range of plant-based alternatives to dairy products, such as milks, creams, yogurts, and cheeses due to the increasing demand from consumers for more sustainable, healthy, and ethical products. These dairy alternatives are often designed to mimic the desirable physicochemical, functional, and sensory properties of real dairy products, such as their appearance, texture, mouthfeel, flavor, and shelf-life. At present, there is a lack of systematic testing methods to characterize the properties of plant-based dairy alternatives. The purpose of this review is to critically evaluate existing methods and recommend a series of standardized tests that could be used to quantify the properties of fluid plant-based milk alternatives (milk and cream). These methods could then be used to facilitate the design of milk alternatives with somewhat similar attributes as real dairy milk by comparing their properties under standardized conditions. Moreover, they could be used to facilitate comparison of the properties of milk alternatives developed in different laboratories.

Development of Next-Generation Nutritionally Fortified Plant-Based Milk Substitutes: Structural Design Principles

Consumers are increasingly interested in decreasing their dietary intake of animal-based food products, due to health, sustainability, and ethical concerns. For this reason, the food industry is creating new products from plant-based ingredients that simulate many of the physicochemical and sensory attributes associated with animal-derived foods, including milk, eggs, and meat. An understanding of how the ingredient type, amount, and organization influence the desirable physicochemical, sensory, and nutritional attributes of these plant-based foods is required to achieve this goal. A potential problem with plant-based diets is that they lack key micronutrients, such as vitamin B12, vitamin D, calcium, and ω-3 fatty acids. The aim of this review is to present the science behind the creation of next-generation nutritionally fortified plant-based milk substitutes. These milk-like products may be formed by mechanically breaking down certain plant materials (including nuts, seeds, and legumes) to produce a dispersion of oil bodies and other colloidal matter in water, or by forming oil-in-water emulsions by homogenizing plant-based oils and emulsifiers with water. A brief overview of the formulation and fabrication of plant-based milks is given. The relationship between the optical properties, rheology, and stability of plant-based milks and their composition and structure is then covered. Approaches to fortify these products with micronutrients that may be missing from a plant-based diet are also highlighted. In conclusion, this article highlights how the knowledge of structural design principles can be used to facilitate the creation of higher quality and more sustainable plant-based food products.

Green approach in food nanotechnology based on subcritical water: effects of thyme oil and saponin on characteristics of the prepared oil in water nanoemulsions

Thyme oil in water nanomulsion was prepared under subcritical water conditions using water and saponin, as solvent and emulsifier, respectively. Gas chromatography revealed that there were 44 bioactive components in the extracted thyme essential oil which, thymol and carvacrol were two mains of them. Experiments were designed based on central composite design and effects of amounts of saponin and thyme essential oil were evaluated on particle size, polydispersity index (PDI) and zeta potential of the prepared nanoemulsions using response surface methodology. Obtained results revealed that more desirable thyme oil nanoemulsions with minimum particle size (184.51 nm) and PDI (0.514), and maximum zeta potential (- 22.51 mV) were prepared using 0.94 g of saponin and 0.28 mL of thyme essential oil. Furthermore, results indicated that prepared nanoemulsion using obtained optimum production conditions had relatively high antioxidant activity (24%) and high antibacterial and antifungal activities against Staphylococcus aureus and Penicillium digitatum.

Impact of curcumin delivery system format on bioaccessibility: nanocrystals, nanoemulsion droplets, and natural oil bodies

Curcumin, a hydrophobic yellow-orange crystalline substance derived from plants, is claimed to exhibit a broad range of biological activities. Its application in functional foods and beverages is often limited by its low solubility in aqueous media, chemical instability, and low bioavailability. Previously, we have shown that curcumin can be successfully loaded into emulsions using the pH-shift method. In this study, we compared the efficacy of curcumin crystals dispersed in water (control) with three delivery systems produced using the pH-shift method: curcumin nanocrystals; curcumin-loaded nanoemulsions; and curcumin-loaded soy oil bodies. The nanoemulsions and oil bodies formed creamy yellow dispersions that were stable to creaming, whereas the nanocrystals formed a cloudy yellow-orange suspension that was prone to sedimentation. The gastrointestinal fate of the delivery systems was assessed using a static in vitro digestion model consisting of mouth, stomach, and small intestine phases. The nanoemulsions and oil bodies were rapidly and fully digested, while the nanocrystals were not. All three systems were relatively stable to chemical transformation in the in vitro digestion model. The nanocrystals gave a low bioaccessibility but the other two systems gave a high bioaccessibility, which was attributed to their ability to form mixed micelles to solubilize the curcumin. These results have important implications for the creation of more effective delivery systems for curcumin.

Impact of sodium caseinate, soy lecithin and carrageenan on functionality of oil-in-water emulsions

Oil-in-water emulsions are the main component of creamers, which are used to cream cold or hot coffee. These emulsions must provide the required lightening power and remain physically stable when introduced into hot acidic coffee solutions. In this study, model oil-in-water emulsions stabilized with mixed emulsifiers of sodium caseinate (0.5%) and soy lecithin (0.5%) were fabricated and their physical properties were examined over a range of pH values (pH 3.5 to 7). These model oil-in-water emulsions had strong lightening power (L* ≈ 87) and good physical stability from pH 5.5 to 7 but were unstable to gravitational separation below pH 5 due to caseinate aggregation around its isoelectric point. Addition of λ-carrageenan (0.05 to 0.175%) to the formulations prior to homogenization effectively improved their pH stability, while addition of κ-carrageenan was ineffective. The significantly higher level of sulfated ester groups in λ-carrageenan may have created a strong electrostatic repulsion between the oil particles, inhibiting their association. Our study suggests that some of the caseinate in coffee creamers can be replaced with plant-based lecithins, but that a plant-based polysaccharide is also needed to ensure their stability when added to hot acidic coffees.

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.

Characterization of physical properties and electronic sensory analyses of citrus oil-based nanoemulsions

Citrus oils and their emulsions have been widely used in food and beverage products due to their flavor, various beneficial health functions and relative high solubility for lipophilic bioactive components. However, the non-digestibility and instability has limited the application of emulsions made from a single type of citrus oil. In this study, common triacylglycerol oils (i.e. corn oil and MCT oil) and citrus oils (i.e. bergamot oil and sweet orange oil) were used in combination with different mixing ratios (triacylglycerol oil:citrus oil = 1:0, 9:1, 5:1, 3:1, 1:1 and 0:1) to produce various nanoemulsions (10% oil phase), and their physical and electronic sensory properties were systematically characterized. The results demonstrated that the mixed oil nanoemulsions were much more stable than pure citrus oil emulsions. Electronic nose, electronic eye and electronic tongue were shown to be able to provide informative evaluation of the electronic sensory of the emulsions. Data-fitting of these electronic sensory devices significantly improved the effective discrimination and accuracy of sensory evaluation of the emulsions. These results provided basis for using triacylglycerol oils and citrus oils in combination to produce nanoemulsions with superior physical and electronic sensory properties. Moreover, the electronic sensory evaluation method utilized in this study provided a useful approach for evaluation of emulsion-based food and beverage products.

Sugar Beet Extract (Beta vulgaris L.) as a New Natural Emulsifier: Emulsion Formation

The interfacial and emulsion-forming properties of sugar beet extract (Beta vulgaris L.) were examined and compared to a Quillaja extract that is widely used within the food industry. We investigated the influence of extract concentration on surface activity at oil-water and air-water interfaces and on the formation of oil-in-water emulsions (10% w/w, pH 7). Sugar beet extract reduced the interfacial tension up to 38% at the oil-water interface, and the surface tension up to 33% at the air-water surface. The generated emulsions were negatively charged (ζ ≈ -46 mV) and had the smallest particle sizes (d₄₃) of ∼1.3 μm at a low emulsifier-to-oil ratio of 0.75:10. Applying lower or higher extract concentrations increased the mean particle sizes. The smallest emulsions were formed at an optimum homogenization pressure of 69 MPa. Higher homogenization pressures led to increased particle sizes. Overall, sugar beet extract showed high surface activity. Furthermore, the formation of small emulsion droplets was successful; however, the droplets were bigger compared to those from the Quillaja extract. These results indicate sugar beet as an effective natural emulsifier that may be utilized for a variety of food and beverage applications.