Multiple Emulsions for Enhanced Delivery of Vitamins and Iron Micronutrients and Their Application for Food Fortification

Cyclodextrins and their potential applications for delivering vitamins, iron, and iodine for improving micronutrient status

Cyclodextrins (CDs) have been investigated as potential biopolymeric carriers that can form inclusion complexes with numerous bioactive ingredients. The inclusion of micronutrients (e.g. vitamins or minerals) into cyclodextrins can enhance their solubility and provide oxidative or thermal stability. It also enables the formulation of products with extended shelf-life. The designed delivery systems with CDs and their inclusion complexes including electrospun nanofibers, emulsions, liposomes, and hydrogels, show potential in enhancing the solubility and oxidative stability of micronutrients while enabling their controlled and sustained release in applications including food packaging, fortified foods and dietary supplements. Nano or micrometer-sized delivery systems capable of controlling burst release and permeation, or moderating skin hydration have been reported, which can facilitate the formulation of several personal and skin care products for topical or transdermal delivery of micronutrients. This review highlights recent developments in the application of CDs for the delivery of micronutrients, i.e. vitamins, iron, and iodine, which play key roles in the human body, emphasizing their existing and potential applications in the food, pharmaceuticals, and cosmeceuticals industries.

Recent advances in iron encapsulation and its application in food fortification

Iron (Fe) is an important element for our body since it takes part in a huge variety of metabolic processes. However, the direct incorporation of Fe into food fortification causes a number of problems along with undesirable organoleptic properties. Thus, encapsulation has been suggested to alleviate this problem. This study first sheds more light on the Fe encapsulation strategies and comprehensively explains the results of Fe encapsulation studies in the last decade. Then, the latest attempts to use Fe (in free or encapsulated forms) to fortify foods such as bakery products, dairy products, rice, lipid-containing foods, salt, fruit/vegetable-based products, and infant formula are presented. Double emulsions are highly effective at keeping their Fe content and display encapsulation efficiency (EE) > 88% although it decreases upon storage. The encapsulation by gel beads possesses several advantages including high EE, as well as reduced and great Fe release in gastric and duodenal conditions, respectively. Cereals, particularly bread and wheat, are common staple foods globally; they are very suitable for food fortification by Fe derivatives. Nevertheless, the majority of Fe in flour is available as salts of phytic acid (IP6) and phytates, reducing Fe bioavailability in the human body. The sourdough process degrades IP6 completely while Chorleywood Bread Making Process and conventional processes decrease it by 75% in comparison with whole meal flour.

Preparation and characterization of an iron-β-cyclodextrin inclusion complex: factors influencing the host-guest interaction

Cyclodextrins have received attention recently due to their superior binding with countless hydrophobic molecules. The host-guest interaction between the cyclodextrin cavity and the hydrophobic component not only facilitates the formation of a strong inclusion complex (IC), but also improves its stability against thermal degradation. The functionality of cyclodextrins for the delivery of hydrophilic components is less explored in comparison. This study discusses the application of β-cyclodextrin (βCD) for the delivery of highly bioavailable and hydrophilic iron, ferric sodium EDTA, which exhibits great functionality in the presence of polyphenols and phytates with potential application in food fortification. The formation of IC was dependent on the cyclodextrin amount and alcoholic co-solvent and was influenced by the stirring duration. For ferric sodium EDTA, the highest inclusion rate (IR) of ∼77% was obtained after 72 hours of mixing in 25.4% (v/v) alcohol at a ratio of iron : βCD of 1 : 6. A higher IR (∼96%) was obtained after 6 hours of stirring with less soluble ferrous ammonium phosphate in comparison. The melting temperature (T_m) of the ferrous ammonium phosphate complex increased from ∼172 to ∼294 °C. The high IR and enhanced thermal resistance of the complex make βCDs potential carriers for ferrous ammonium phosphate delivery and fortification of foods processed at high temperatures.

Determination of the Dominating Coalescence Pathways in Double Emulsion Formulations by Use of Microfluidic Emulsions

In water-in-oil-in-water (W1/O/W2) double emulsions several irreversible instability phenomena lead to changes. Besides diffusive processes, coalescence of droplets is the main cause of structural changes. In double emulsions, inner droplets can coalesce with each other (W1–W1 coalescence), inner droplets can be released via coalescence (W1–W2 coalescence) and oil droplets can coalesce with each other (O–O coalescence). Which of the coalescence pathways contributes most to the failure of the double emulsion structure cannot be determined by common measurement techniques. With monodisperse double emulsions produced with microfluidic techniques, each coalescence path can be observed and quantified simultaneously. By comparing the occurrence of all possible coalescence events, different hydrophilic surfactants in combination with PGPR are evaluated and discussed with regard to their applicability in double emulsion formulations. When variating the hydrophilic surfactant, the stability against all three coalescence mechanisms changes. This shows that measuring only one of the coalescence mechanisms is not sufficient to describe the stability of a double emulsion. While some surfactants are able to stabilize against all three possible coalescence mechanisms, some display mainly one of the coalescence mechanisms or in some cases all three mechanisms are observed simultaneously.

Preparation and characterization of W1 /O/W2 emulsions stabilized by glycated and heat-modified egg white proteins

BACKGROUND

Water-in-oil-in-water (W₁ /O/W₂ ) emulsions stabilized by protein-carbohydrate complexes were prepared from an inner water phase (W₁ ), an oil phase (O) and an outer water phase (W₂ ). The complexes consisted of heat-induced aggregates (HIAs) of isomalto-oligosaccharide/egg white protein Maillard conjugates. The effects of polyglycerol ester of polyricinoleic acid (PGPR) concentration, HIA concentration, W₁ -to-O volume ratio and W₁ /O-to-W₂ volume ratio on the properties of the W₁ /O/W₂ emulsions were systematically investigated.

RESULTS

At sufficiently high PGPR concentrations (>2%), the emulsions possess a high negative charge (≈-44 mV). The encapsulation efficiency of the emulsions, which was determined by incorporating a hydrophilic yellow dye in the inner water phase prior to homogenization, was relatively high (up to 93%) and did not change significantly during 14-day storage at 4 °C. All emulsions were fluids that exhibited shear thinning behavior.

CONCLUSION

Overall, this study shows that nature-derived emulsifiers can be used to create W₁ /O/W₂ emulsions suitable for application in the food industry. In addition, we provided a viable strategy to encapsulate water-soluble nutrients. © 2022 Society of Chemical Industry.

Multiple Pickering emulsions stabilized by the same particles with different extent of hydrophobization in situ

Multiple emulsions are widely used in pharmaceuticals, foods, and cosmetics. However, those stabilized by surfactants with different HLB values are generally unstable due to the diffusion of the surfactants between inner and outer interfaces. Here, we report that multiple W/O/W emulsions can be prepared by using the same particles in combination with a surfactant of different concentrations. The less surface-active raw CaCO₃ nanoparticles can be hydrophobized to surface-active in situ by adsorption of the anionic surfactant SDS, and the wettability of the particles can be controlled to be suitable for stabilizing both O/W and W/O Pickering emulsions by adjusting the surfactant concentration. With toluene as oil phase, the CaCO₃ particles at 1.0 wt% tend to stabilize a W/O emulsion in the presence of 3 mm SDS in an aqueous solution, which can then be further dispersed in an aqueous phase with 1.0 wt% CaCO₃ and SDS below 1 mm to form a W/O/W multiple emulsion. The effects of the ratio of W/O emulsion to the outer water phase and the preparation methods on stabilization of multiple emulsions were examined. With a ratio smaller than 3:1 and by gentle magnetic stirring, the multiple emulsions obtained can stay stable for at least a month without coalescence. This simple method not only ensures stabilization of multiple emulsions but also avoids complicated synthesis of colloid particles with different wettability.

Double emulsions as delivery systems for iron: Stability kinetics and improved bioaccessibility in infants and adults

Iron deficiency is one of the main causes of anemia in the world, especially in children and women, so food fortification through microencapsulation is a viable alternative to combat this deficiency. The present work aimed to encapsulate iron in a water-in-oil-in-water double emulsion (W₁/O/W₂), which was formed with whey protein isolate and polyglycerol polyricinoleate as the emulsifying agents, tara gum as a thickening agent, and sucrose as an osmotic active substance. The double emulsion formed with 12% whey protein isolate, 0.8% tara gum, and 2% sucrose presented high encapsulation efficiency (96.95 ± 1.00%) and good stability (up to 7 days). Additionally, after the in vitro gastrointestinal simulations, the bioaccessibility was high for adults (49.54 ± 5.50%) and infants (39.71 ± 2.33%). Finally, the study show that double emulsions can form stable systems with high iron bioaccessibility even in infant gastric systems, which indicates the possibility of using double emulsions to fortify food with iron.

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Stable double emulsions were obtained using WPI and PGPR as emulsifiers.

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Tara gum ensured an increase in the general stability of the emulsion.

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High bioaccessibility of iron were obtained for adults and infants.

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Emulsions are presented as a potential alternative to be used in iron-fortified food.

Oil Droplet Coalescence in W/O/W Double Emulsions Examined in Models from Micrometer- to Millimeter-Sized Droplets

Water-in-oil-in-water (W1/O/W2) double emulsions must resist W1–W1, O–O and W1–W2 coalescence to be suitable for applications. This work isolates the stability of the oil droplets in a double emulsion, focusing on the impact of the concentration of the hydrophilic surfactant. The stability against coalescence was measured on droplets ranging in size from millimeters to micrometers, evaluating three different measurement methods. The time between the contact and coalescence of millimeter-sized droplets at a planar interface was compared to the number of coalescence events in a microfluidic emulsion and to the change in the droplet size distributions of micrometer-sized single and double emulsions. For the examined formulations, the same stability trends were found in all three droplet sizes. When the concentration of the hydrophilic surfactant is reduced drastically, lipophilic surfactants can help to increase the oil droplets’ stability against coalescence. This article also provides recommendations as to which purpose each of the model experiments is suited and discusses advantages and limitations compared to previous research carried out directly on double emulsions.

Using Resonance-Enhanced Multiphoton Ionization Time-of-Flight Mass Spectrometry to Evaluate the Movement of a Constituent in a Multiple Emulsion

Herein, we propose a method for evaluating the movement of a constituent in a multiple emulsion while maintaining its original dispersed condition. In this study, an oil-in-water-in-oil (O1/W/O2) emulsion was prepared using a two-step emulsification method with styrene as an analyte species in the inner phase (O1). The emulsion was measured using resonance-enhanced multiphoton ionization time-of-flight mass spectrometry without pretreatment such as centrifugation. From a series of obtained mass spectra, a time profile for the peak areas arising from styrene was constructed. When the emulsion was measured immediately following preparation, a time profile composed of a base, positive, and negative signals confirmed the presence of styrene in the O2, O1, and W phases, respectively. Moreover, while a small amount of styrene was present in the inner O1 phase, almost all of the styrene was found in the outer O2 phase. Furthermore, the results of the obtained time profile were converted into a box plot, and a method for the selection of the base, positive, and negative signals was tentatively determined. Then, the movement of styrene among the phases could be evaluated using the time courses of these signals; the time constant of the movement of styrene from an O1/W droplet to the O2 phase was calculated to be 0.8 h.

Power Ultrasound-Assisted Impregnation of Apple Cubes with Vitamin B12

This work explores the use of ultrasound (US) as a means of intensifying the impregnation of apple cubes with vitamin B12 (cyanocobalamin). The effect of different US power densities (90 and 200 WL−1) and treatment times (5, 10, and 15 min) was evaluated, on vitamin load, vitamin stability, and physicochemical and microstructural properties of the fruit matrix. The US enhanced the impregnation producing high cyanocobalamin content products (0.12–0.19 mg vitamin/g db.). Vitamin losses in the sonication medium due to US application were not significant. Impregnated samples exhibited higher moisture and lower soluble solids with respect to the untreated fruit. Changes in chromatic coordinates were well correlated to vitamin uptake. Only at the highest treatment intensities (200 WL−1, 10, and 15 min) was a marked softening observed, which agreed with the microstructural changes observed in fruit tissues. Results permit US-assisted impregnation to be considered a promising technology in the preparation of vitamin B12 fortified apple cubes.