Physicochemical stability of β-carotene and α-tocopherol enriched nanoemulsions: Influence of carrier oil, emulsifier and antioxidant

Effect of wall material on lipophilic functional compounds of high oleic palm oil emulsions encapsulated by Refractance Window drying

High-oleic palm oil is a food-grade oil with desirable properties, as it is characterised by having an oleic acid concentration above 50 % and a high vitamin E and provitamin A content. This study investigated the effect of different combinations of two wall materials (whey protein (WP) and Capsul®, a commercial octenyl succinic anhydride modified starch (OSA-MS)) on the concentration of provitamin A, vitamin E and oleic acid, and the physical properties of high oleic palm oil emulsions encapsulated by Refractance Window drying technology. Wall material composition significantly affected (p < 0.05) all response variables, and R2 values were above 0.75 for all responses. Phytonutrient preservation showed its highest at an OSA-MS: WP concentration ratio of 1: 3. Optimal results were achieved (minimum moisture content, water activity and hygroscopicity, and maximum encapsulation efficiency and phytonutrient preservation) at an OSA-MS concentration of 8.13 % and WP concentration of 91.87 %. Flakes were obtained as a solid structure that protects oil's phytonutrients with 94 %, 75 % and 87 % of preservation of oleic acid, vitamin E and carotenoids, respectively. It shows that the wall material combination and encapsulation technique are suitable for obtaining lipophilic functional compounds.

Effect of α-tocopherol on the oxidative stability of horse oil-in-water emulsion during storage

Horse oil-in-water (O/W) emulsions were prepared and α-tocopherol was added at 0, 100, 200, and 500 ppm (α-T0, α-T100, α-T200, α-T500) to enhance its oxidative stability. Mean particle diameters of the O/W emulsions were 243-299 nm. Zeta potential values increased with the addition of α-tocopherol; however, they decreased during storage at 40 °C for 30 days. Particle size distribution of the O/W emulsion with α-tocopherol remained the same as that of α-T0. For lipid oxidation, the peroxide values of α-T0 and α-T500 were greatly increased from 2.96 and 2.89 to 13.76 and 12.46 mmol/kg oil, respectively, after 30 days. The α-T100 and α-T200 maintained lower peroxide values than other emulsions. Thiobarbituric acid-reactive substance values of α-T0 and α-T500 were higher than those of α-T100 and α-T200. These results indicate that the addition of α-tocopherol from 100 to 200 ppm to the horse oil-in-water emulsion effectively improves its oxidative stability during storage.

Effects of the substitution of cow’s milk with soymilk on the micronutrients, microbial, and sensory qualities of yoghurt

The consumption of imported dairy products is high especially in developing countries including Nigeria where little or no milk is produced locally which makes the products expensive, out of reach to common consumers and also inconvenient for lactose intolerance and vegans. Soymilk, as plant-based milk was substituted for cow’s milk in parts and in whole for the production of yoghurt and the effect of substitution was evaluated on the minerals, vitamins, microbial, and sensory properties of the products using the established methods. Significant differences (p < 0.05) exits among the yoghurt samples in the micronutrient contents. The soymilk substitution produced yoghurts with trace/macro mineral contents’ range of 0.14–28.50 mg/100 g and vitamin contents (ranged 0.02–0.43 mg/100 g) that were of comparable range of values with the yoghurt made with 100% cow’s milk (0.21–29.60 mg/100 g minerals and 0.05–0.58 mg/100 g vitamins). Generally, no significant difference (p < 0.05) was observed in most of the sensory attributes evaluated (range 8.00–8.01) in the entire samples (except in the 100% soymilk yoghurt). The microbial analysis proved the safety of the entire products for consumption. These showed the positive effect of substituting soymilk for cow’s milk at all the levels used, thus, the lactose intolerance and vegans can find alternative to dairy yoghurt in the 100% soymilk substitution and enjoy the functional health benefits of yoghurt. Also, the total dependence on importation of dairy milk and cost of production of composited milk yoghurt could be reduced to improve the nation’s economy and make the product economically accessible to common man.

Graphical abstract

Recent progresses in the delivery of β-carotene: From nano/microencapsulation to bioaccessibility

Beta-carotene (BC) as an efficient pro-vitamin is effective in improving vision, immune system and cognitive function as well as preventing coronary diseases and cancer. However, besides its poor chemical stability, the high lipophilic nature of BC reduces its dispersibility and consequently bioavailability which limits its application into food, pharmaceutical and nutraceuticals. Different carriers with vesicular or particulate structures have been studied and utilized for promoting BC solubility, dispersibility, and protection against diverse operational or environmental stresses and also controlling BC release and subsequent bioaccessibility. The current study, therefore reviews different micro/nanocarriers reported on BC encapsulation with special focusing on its bioavailability. Liposomal structures have been successfully used for enhancing BC stability and bioavailability. Besides, emulsion-based carriers including Pickering emulsions, nanoemulsions and microemulsions have been widely evaluated for BC encapsulation and protection. In addition, lipid-based nanoparticles and nanostructural carriers have also been applied successfully for this context. Moreover, gel structures including emulgels, hydrogels and oleogels are studied in some researches. Most of these delivery systems led to higher hydro-solubility and dispersibility of BC which consequently increased its bioavailability; thereupon could promote its application into food, cosmetic and nutraceutical products. However, for remarkable incorporation of BC and other bioactive compounds into edible products, the safety and toxicological aspects of these delivery system especially those designed in nano scale should be addressed in the further researches.

A review of recent progress in improving the bioavailability of nutraceutical-loaded emulsions after oral intake

Increasing awareness of the health benefits of specific constituents in fruits, vegetables, cereals, and other whole foods has sparked a broader interest in the potential health benefits of nutraceuticals. Many nutraceuticals are hydrophobic substances, which means they must be encapsulated in colloidal delivery systems. Oil-in-water emulsions are one of the most widely used delivery systems for improving the bioavailability and bioactivity of these nutraceuticals. The composition and structure of emulsions can be designed to improve the water dispersibility, physicochemical stability, and bioavailability of the encapsulated nutraceuticals. The nature of the emulsion used influences the interfacial area and properties of the nutraceutical-loaded oil droplets in the gastrointestinal tract, which influences their digestion, as well as the bioaccessibility, metabolism, and absorption of the nutraceuticals. In this article, we review recent in vitro and in vivo studies on the utilization of emulsions to improve the bioavailability of nutraceuticals. The findings from this review should facilitate the design of more efficacious nutraceutical-loaded emulsions with increased bioactivity.

The effect of microfluidization pressure on the physical stability of vitamin A in oil-in-water emulsions

In this study, vitamin A was encapsulated within oil-in-water emulsions by high-pressure microfluidization prepared using phosphate buffer (90%), corn oil (10%), and whey protein isolate (2%) as an emulsifier. The influence of microfluidization pressure (10, 50, 100, 200 MPa) on the particle size, zeta potential, and the physical and chemical stability of emulsions was evaluated. The physical stability of emulsion was determined by multiple light scattering technique. The content of vitamin A was measured by HPLC–DAD during an accelerated storage test at 40 °C during 4 weeks. The color of the samples was monitored using a colorimeter. The results showed that the lowest particle size distribution and the highest absolute value of zeta potential on the droplets’ surface charge were obtained by applying a pressure of 100 MPa. Nanoemulsions prepared at 100 MPa also showed the highest colloidal stability. However, higher microfluidization pressure (up to 200 MPa) had a negative impact on the prepared emulsion’s stability. The results of chemical stability by HPLC measurements during storage time were in agreement with the results of physical stability and color change.

Optimisation of the physicochemical stability of extra virgin olive oil-in-water nanoemulsion: processing parameters and stabiliser type

Extra virgin olive oil-in-water nanoemulsions stabilised with synthetic or clean label surfactants (Tween 20 or soy lecithin) was prepared using high-pressure homogenisation (HPH). The effect of HPH pressure and the number of cycles were assessed through response surface methodology to optimise homogenisation processing parameter. Mean droplet diameter (MDD), polydispersity index (PDI), thermal stability and oxidation stability of the resulting emulsions were evaluated. The results showed that the formation and stability of nanoemulsions can be affected by the homogenisation processing parameters (pressure and cycles) and the properties of surfactants (interfacial tension, viscoelasticity and molecule structure). Although MDD and PDI of Tween 20 stabilised nanoemulsions were influenced by homogenisation pressure and cycles, there was not a significant effect on lecithin-stabilised nanoemulsions. A homogenisation pressure of at least 400 bars produced Tween 20 stabilised nanoemulsion (MDD < 200 nm), whereas lecithin-stabilised nanoemulsion were obtained after high-speed homogenisation without using HPH. HPH at 400 bars for 1 cycle produced nanoemulsions with greater physical stability when using either Tween 20 or lecithin. Tween 20 stabilised nanoemulsion showed significantly higher (p < 0.05) thermal stability and lipid oxidative stability than lecithin-stabilised nanoemulsion. Following an optimisation study using regression modelling, the optimal homogenisation parameter for MDD of Tween 20 stabilised emulsion was found at pressure of 764 bars with 1 cycle, while lecithin-stabilised emulsion was found at pressure of 3 bars with 2 cycles. Overall, this study has important implications for optimising nanoemulsion production for potential application in the food industry.

Vitamin A fortification: Recent advances in encapsulation technologies

Vitamin A is an essential micronutrient whose deficiency is still a major health concern in many regions of the world. It plays an essential role in human growth and development, immunity, and vision, but may also help prevent several other chronic diseases. The total amount of vitamin A in the human diet often falls below the recommended dietary allowance of approximately 900-1000 μ $ \umu $ g/day for a healthy adult. Moreover, a significant proportion of vitamin A may be degraded during food processing, storage, and distribution, thereby reducing its bioactivity. Finally, the vitamin A in some foods has a relatively low bioavailability, which further reduces its efficacy. The World Health Organization has recommended fortification of foods and beverages as a safe and cost-effective means of addressing vitamin A deficiency. However, there are several factors that must be overcome before effective fortified foods can be developed, including the low solubility, chemical stability, and bioavailability of this oil-soluble vitamin. Consequently, strategies are required to evenly disperse the vitamin throughout food matrices, to inhibit its chemical degradation, to avoid any adverse interactions with any other food components, to ensure the food is palatable, and to increase its bioavailability. In this review article, we discuss the chemical, physical, and nutritional attributes of vitamin A, its main dietary sources, the factors contributing to its current deficiency, and various strategies to address these deficiencies, including diet diversification, biofortification, and food fortification.

Physical and Chemical Characterisation of Conventional and Nano/Emulsions: Influence of Vegetable Oils from Different Origins

The processes of oil production play an important role in defining the final physical and chemical properties of vegetable oils, which have an influence on the formation and characteristics of emulsions. The objective of this work was to investigate the correlations between oils’ physical and chemical properties with the stability of conventional emulsions (d > 200 nm) and nanoemulsions (d < 200 nm). Five vegetable oils obtained from different production processes and with high proportion of unsaturated fatty acids were studied. Extra virgin olive oil (EVOO), cold-pressed rapeseed oil (CPRO), refined olive oil (OO), refined rapeseed oil (RO) and refined sunflower oil (SO) were used in this study. The results showed that the physicochemical stability of emulsion was affected by fatty acid composition, the presence of antioxidants, free fatty acids and droplet size. There was a significant positive correlation (p < 0.05) between the fraction of unsaturated fatty acids and emulsion oxidative stability, where SO, OO and EVOO showed a significantly higher lipid oxidative stability compared to RO and CPRO emulsions. Nanoemulsions with a smaller droplet size showed better physical stability than conventional emulsions. However, there was not a significant correlation between the oxidative stability of emulsions, droplet size and antioxidant capacity of oils.

Fate of β-Carotene within Loaded Delivery Systems in Food: State of Knowledge

Nanotechnology has opened new opportunities for delivering bioactive agents. Their physiochemical characteristics, i.e., small size, high surface area, unique composition, biocompatibility and biodegradability, make these nanomaterials an attractive tool for β-carotene delivery. Delivering β-carotene through nanoparticles does not only improve its bioavailability/bioaccumulation in target tissues, but also lessens its sensitivity against environmental factors during processing. Regardless of these benefits, nanocarriers have some limitations, such as variations in sensory quality, modification of the food matrix, increasing costs, as well as limited consumer acceptance and regulatory challenges. This research area has rapidly evolved, with a plethora of innovative nanoengineered materials now being in use, including micelles, nano/microemulsions, liposomes, niosomes, solidlipid nanoparticles, nanostructured lipids and nanostructured carriers. These nanodelivery systems make conventional delivery systems appear archaic and promise better solubilization, protection during processing, improved shelf-life, higher bioavailability as well as controlled and targeted release. This review provides information on the state of knowledge on β-carotene nanodelivery systems adopted for developing functional foods, depicting their classifications, compositions, preparation methods, challenges, release and absorption of β-carotene in the gastrointestinal tract (GIT) and possible risks and future prospects.

Pomegranate seed oil nanoemulsion enriched by α-tocopherol; the effect of environmental stresses and long-term storage on its physicochemical properties and oxidation stability

In this study, pomegranate seed oil (PSO) nanoemulsions loading different amounts of α-tocopherol (0-40%) were produced. The nanoemulsions were fabricated by ultra-sonication method and the influence of thermal treatment (20-90 °C), pH (2-8) and ionic strength (0-500 mM NaCl) were investigated on physicochemical properties of all treatments. Moreover, the oxidative stability and α-tocopherol degradation were also assessed on optimal enriched nanoemulsion formulation during 50-day storage. The droplet diameter, viscosity, antioxidant activity, encapsulation efficiency and loading capacity of optimal formulation were 37.5 nm, 514 cp, 92%, 3.45% and 92.5%, respectively. The peroxide value changed in the range of 4.5-5.3 and 6.7-10.5 meq O₂/kg in loaded and unloaded nanoemulsions, respectively. Transmission electron microscopy demonstrated spherical morphology of nanoemulsion droplets with diameter average of 40 nm. This study suggested that PSO nanoemulsion loading α-tocopherol could be introduced as delivery system with favorable features under severe environmental conditions.

Potential of Nanonutraceuticals in Increasing Immunity

Nutraceuticals are defined as foods or their extracts that have a demonstrably positive effect on human health. According to the decision of the European Food Safety Authority, this positive effect, the so-called health claim, must be clearly demonstrated best by performed tests. Nutraceuticals include dietary supplements and functional foods. These special foods thus affect human health and can positively affect the immune system and strengthen it even in these turbulent times, when the human population is exposed to the COVID-19 pandemic. Many of these special foods are supplemented with nanoparticles of active substances or processed into nanoformulations. The benefits of nanoparticles in this case include enhanced bioavailability, controlled release, and increased stability. Lipid-based delivery systems and the encapsulation of nutraceuticals are mainly used for the enrichment of food products with these health-promoting compounds. This contribution summarizes the current state of the research and development of effective nanonutraceuticals influencing the body's immune responses, such as vitamins (C, D, E, B12, folic acid), minerals (Zn, Fe, Se), antioxidants (carotenoids, coenzyme Q10, polyphenols, curcumin), omega-3 fatty acids, and probiotics.

Interactions of β-carotene with WPI/Tween 80 mixture and oil phase: Effect on the behavior of O/W emulsions during in vitro digestion

This study investigated the impact of adding β-carotene on the structure of fresh O/W emulsions with different oil phase (sunflower oil-LCT or NEOBEE®1053-MCT) and emulsifiers (WPI, Tween 80 - T80 or WPI/T80 mixture). In this sense, the behavior of emulsions through the gastrointestinal tract, the stability and bioaccessibility of β-carotene were also assessed. The β-carotene reduced the interfacial tension of the LCT/MCT-water systems. The addition of β-carotene promoted an increase of viscoelasticity of LCT/MCT-T80 (0.5%WPI/0.5%T80 and 1%T80 w/w) interfaces, but an increase of WPI content reduced the viscoelasticity of interfacial layers (LCT/MCT-1% WPI). These changes in the interface properties influenced the mean droplet size and ζ-potential of the fresh emulsions. LCT systems presented similar bioaccessibility/stability of β-carotene. However, β-carotene entrapped within protein-coated MCT droplets was more stable than within T80-MCT systems. Our results show that β-carotene interacted with other ingredients of emulsions changing their properties and behavior under gastrointestinal tract as well as the stability/bioaccessibility of β-carotene.

Encapsulation of Lipid-Soluble Bioactives by Nanoemulsions

Lipid-soluble bioactives are important nutrients in foods. However, their addition in food formulations, is often limited by limited solubility and high tendency for oxidation. Lipid-soluble bioactives, such as vitamins A, E, D and K, carotenoids, polyunsaturated fatty acids (PUFA) and essential oils are generally dispersed in water-based solutions by homogenization. Among the different homogenization technologies available, nanoemulsions are one of the most promising. Accordingly, this review aims to summarize the most recent advances in nanoemulsion technology for the encapsulation of lipid-soluble bioactives. Modern approaches for producing nanoemulsion systems will be discussed. In addition, the challenges on the encapsulation of common food ingredients, including the physical and chemical stability of the nanoemulsion systems, will be also critically examined.

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.

Development of Oral Delivery Systems with Enhanced Antioxidant and Anticancer Activity: Coix Seed Oil and β-Carotene Coloaded Liposomes

Fortifying food and beverage products with combinations of bioactive agents is a major initiative within the food industry because of their potentially additive or even synergistic benefits for human health. Coix seed oil (CSO) has been reported to possess anticancer activity, whereas β-carotene (βC) is a natural antioxidant that may also exhibit anticancer activity. However, both of these bioactives are insoluble in water and have poor oral bioavailability. The aim of this study was to overcome these obstacles by encapsulating both βC and CSO into liposomes (L-βC-CSO). The effect of different combinations of these two bioactive agents on the physiochemical properties, stability, release, antioxidant activity, and anticancer activity of the liposomes was then determined. Increasing the CSO level decreased the βC entrapment efficiency, increased the particle size, reduced the polydispersity, and raised the magnitude of the surface potential of the bioactive-loaded liposomes. Moreover, the βC and CSO levels affected their orientation within the lipid bilayer, which also influences the physiochemical properties, stability, and in vitro release behavior of the system. Compared to liposomes containing single bioactive types, the combined systems exhibited higher bioavailability and increased anticancer and antioxidant activity. These results suggest that the combined bioactive-loaded liposomes could be an efficient formulation for potential applications in functional foods and supplements.

Low-Energy Encapsulation of α-Tocopherol Using Fully Food Grade Oil-in-Water Microemulsions

Encapsulation of active agents, such as vitamins and antioxidants, is one of the possibilities that allow their incorporation in beverages, food, or in pharmaceutical products. Simultaneously, encapsulation protects these active agents from oxidation, producing more stable active compounds. Formation of nanodroplets by spontaneously formed microemulsion (ME) offers, on one hand, a low-energy technology of encapsulation and, on the other hand, because of a small size of the droplets, it assures long-term stability even in harsher environments. In this study, oil-in-water MEs allowed the low-energy encapsulation of α-tocopherol (αToc) into an aqueous medium with the aid of fully food-grade ingredients, using isoamyl acetate as the dispersed oil phase, which was selected between three different types of oils. Both cosurfactant-free and cosurfactant-holder ME systems were formulated, in which Tween 20 and glycerol were employed as the surfactant and the cosurfactant, respectively. The ME monophasic area was determined through the construction of pseudoternary phase diagrams. The encapsulated αToc within 10-20 nm nanocapsules showed radical scavenging activity dependent on the encapsulated amount of αToc, as it was demonstrated by electron paramagnetic resonance spectroscopy. The radical scavenging activity slightly increased within the time investigated, indicating a slow release of the active compound from the nanodroplets, which is a promising result for their application, especially in pharmaceuticals.

Enhanced delivery of lipophilic bioactives using emulsions: a review of major factors affecting vitamin, nutraceutical, and lipid bioaccessibility

Many researchers are currently developing emulsion-based delivery systems to increase the bioavailability of lipophilic bioactive agents, such as oil-soluble vitamins, nutraceuticals, and lipids. Oil-in-water emulsions can be specifically designed to improve the bioavailability of these bioactives by altering their composition and structural organization. This article reviews recent progress in understanding the impact of emulsion properties on the bioaccessibility of lipophilic bioactive agents, including oil phase composition, aqueous phase composition, droplet size, emulsifier type, lipid physical state, and droplet aggregation state. This knowledge can be used to design emulsions that can enhance the bioavailability and efficacy of encapsulated hydrophobic bioactives.