Monodisperse W/O/W emulsions encapsulating l-ascorbic acid: Insights on their formulation using microchannel emulsification and stability studies

Vitamin C fortification: need and recent trends in encapsulation technologies

The multifaceted role of vitamin C in human health intrudes several biochemical functions that are but not limited to antioxidant activity, homoeostasis, amino acid synthesis, collagen synthesis, osteogenesis, neurotransmitter production and several yet to be explored functions. In absence of an innate biosynthetic pathway, humans are obligated to attain vitamin C from dietary sources to maintain its optimal serum level (28 μmol/L). However, a significant amount of naturally occurring vitamin C may deteriorate due to food processing, storage and distribution before reaching to the human gastrointestinal tract, thus limiting or mitigating its disease combating activity. Literature acknowledges the growing prevalence of vitamin C deficiency across the globe irrespective of geographic, economic and population variations. Several tools have been tested to address vitamin C deficiency, which are primarily diet diversification, biofortification, supplementation and food fortification. These strategies inherit their own advantages and limitations. Opportunely, nanotechnology promises an array of delivery systems providing encapsulation, protection and delivery of susceptible compounds against environmental factors. Lack of clear understanding of the suitability of the delivery system for vitamin C encapsulation and fortification; growing prevalence of its deficiency, it is a need of the hour to develop and design vitamin C fortified food ensuring homogeneous distribution, improved stability and enhanced bioavailability. This article is intended to review the importance of vitamin C in human health, its recommended daily allowance, its dietary sources, factors donating to its stability and degradation. The emphasis also given to review the strategies adopted to address vitamin c deficiency, delivery systems adopted for vitamin C encapsulation and fortification.

Chemical Stability of Ascorbic Acid Integrated into Commercial Products: A Review on Bioactivity and Delivery Technology

The L-enantiomer of ascorbic acid is commonly known as vitamin C. It is an indispensable nutrient and plays a key role in retaining the physiological process of humans and animals. L-gulonolactone oxidase, the key enzyme for the de novo synthesis of ascorbic acid, is lacking in some mammals including humans. The functionality of ascorbic acid has prompted the development of foods fortified with this vitamin. As a natural antioxidant, it is expected to protect the sensory and nutritional characteristics of the food. It is thus important to know the degradation of ascorbic acid in the food matrix and its interaction with coexisting components. The biggest challenge in the utilization of ascorbic acid is maintaining its stability and improving its delivery to the active site. The review also includes the current strategies for stabilizing ascorbic acid and the commercial applications of ascorbic acid.

Stability and release mechanisms of double emulsions loaded with bioactive compounds; a critical review

Double emulsions (DEs), known as emulsions of emulsions, are dispersion systems in which the droplets of one dispersed liquid are further dispersed in another liquid, producing double-layered liquid droplets. These systems are widely used in the food and pharmaceutical industries due to their ability to co-encapsulate both hydrophilic and hydrophobic bioactive compounds. However, they are sensitive and unstable and their controlled release is challenging. In this study, first, the stability of DEs and their release mechanisms are reviewed. Then, the factors affecting their stability, and the release of bioactive compounds are studied. Finally, modeling of the release in DEs is discussed. This information can be useful to optimize the formulation of DEs in order to utilize them in different industries.

Tea polyphenols encapsulated in W/O/W emulsions with xanthan gum-locust bean gum mixture: Evaluation of their stability and protection

Herein, improvement of the stability of the water-in-oil-in-water (W/O/W) emulsions by addition of xanthan gum (XG)/locust bean gum (LBG) mixture in the inner water phase was aimed. The impact of XG/LBG mixture on the physical stability, microstructure and rheological properties of W/O/W emulsions was investigated. It was found that, compared with the control emulsions, the presence of XG/LBG mixture could improve the stability of W/O/W emulsions against coalescence. The tea polyphenols (TPPs) and XG/LBG mixture were simultaneously included in the internal aqueous phase of the double emulsion and stored at 25 and 40 °C in the dark for 28 d. The results showed that XG/LBG mixture not only had a protective role for TPPs encapsulated in the internal water phase, but also maintained more than 50% of the antioxidant capacity of TPPs.

Ultrasound-assisted production of palm oil-based isotonic W/O/W multiple nanoemulsion encapsulating both hydrophobic tocotrienols and hydrophilic caffeic acid with enhanced stability using oil-based Sucragel

In this work, the effects of thickeners and tonicity towards producing stable palm oil-based water-in-oil-in-water (W/O/W) multiple nanoemulsion using ultrasound and microfluidizer were investigated. Palm oil, Sucragel, polyglycerol polyricinoleate, Tween 80, Xanthan gum, and NaCl were used. W/O/W was formed under the optimized conditions of ultrasound at 40% amplitude and for 180 s of irradiation time, whereas for the microfluidizer, the optimized conditions were 350 bar and 8 cycles. This is the first work that successfully utilized Sucragel (oil-based thickener) in imparting enhanced stability in W/O/W. W/O/W with isotonic stabilization produced the lowest change in the mean droplet diameter (MDD), NaCl concentration, and water content by 1.5%, 2.6%, and 0.4%, respectively, due to reduced water movement. The final optimized W/O/W possessed MDD and dispersity index of 175.5 ± 9.8 and 0.232 ± 0.012, respectively. The future direction of formulating stable W/O/W would be by employing oil phase thickeners and isotonicity. The observed ~12 times lesser energy consumed by ultrasound than microfluidizer to generate a comparable droplet size of ~235 nm, further confirms its potential in generating the droplets energy-efficiently.

Stability, antioxidant activity, in vivo safety and efficacy of creams with standardized wild apple fruit extract: a comparison of conventional and biodegradable emulsifiers

OBJECTIVE

The aim of the study was in vitro and in vivo characterization of cosmetic cream with 6% of standardized wild apple fruit extract, stabilized by conventional non-ionic emulsifier-CEW, in order to determine the influence of emulsifiers (conventional vs. biodegradable) on the characteristics of creams and their effects on the skin.

METHODS

Organoleptic and physico-chemical (pH values and electrical conductivity) analysis was performed, determination of fruit acids-FAs content (using HPLC analysis) and estimation of its antioxidant activity-AA (using DPPH test) during 180 days. In vivo study included following examinations: screening of safety profile (after creams application under occlusion during 24 h at human skin); skin moisturizing potential, transepidermal water loss-TEWL, skin pH after 28 days of cream application and hypopigmentation efficacy 7 days of cream application at artificially induced skin hyperpigmentation.

RESULTS

Investigated cosmetic cream-CEW showed satisfactory organoleptic, physico-chemical characteristics, stability, FAs content (0.13%) and AA (19.25 ± 0.67 %RSC) after preparation, which remained unchanged over the study period. In vivo investigation revealed absence of skin irritation after CEW's application under occlusion. An increase of skin moisturization (after 14 days ΔEC was 18.52 ± 11.51 and after 28 days of applications 16.52 ± 9.36) during 28 day-study, with unchanged TEWL and skin pH values was shown. Decrease of melanin index was revealed, too (after 7 days ΔMI was -31.40 ± 16.50).

CONCLUSION

Cosmetic cream stabilized by conventional emulsifier showed better antioxidant potential and weaker moisturizing and hypopigmentation effects related to the cream with same composition but stabilized by biodegradable emulsifiers. Based on all mentioned above, investigated cosmetic cream might be considered for potential use as modern, stable, safe and efficient cosmetic product in the prevention and/or treatment of oxidative stress-related skin changes and/or damages, for moisturization of dry, even irritated skin as well as for lightening of hyperpigmented skin. RÉSUMÉ: OBJECTIF Le but de l'étude était la caractérisation in vitro et in vivo d'une crème cosmétique contenant 6 % d'extrait normalisé de pomme sauvage, stabilisée par un émulsifiant non ionique conventionnel-CEW, afin de déterminer l'influence des émulsifiants (conventionnels vs biodégradables) sur les caractéristiques des crèmes et les effets sur la peau. MÉTHODES: Des analyses organoleptiques et physico-chimiques (pH et conductivité électrique) ont été effectuées, la détermination de la teneur en acides de fruits et en acides gras polyinsaturés (par CLHP), et l'estimation de sa teneur en activité antioxydante (AA) (à l'aide du test DPPH) pendant 180 jours. L'étude in vivo comprenait les examens suivants : dépistage du profil d'innocuité (après application de crèmes sous occlusion pendant 24 h sur la peau humaine); potentiel d'hydratation de la peau, perte d'eau transépidermique (PETE), pH de la peau après 28 jours d'application de la crème et efficacité de l'hypopigmentation après 7 jours d'application de la crème sur une hyperpigmentation de la peau induite artificiellement. RÉSULTATS: La crème cosmétique-CEW étudiée a montré des caractéristiques organoleptiques, physico-chimiques, une stabilité, une teneur en AG (0,13 %) et en AA (19,25 ± 0,67 % RSC) satisfaisantes après préparation, qui sont demeurées inchangées au cours de la période de l'étude. L'étude in vivo a révélé l'absence d'irritation cutanée après l'application de CEW sous occlusion. Une augmentation de l'hydratation de la peau (après 14 jours de DEC était de 18,52 ± 11,51 et après 28 jours d'applications de 16,52 ± 9,36) pendant l'étude de 28 jours, avec une PETE et des valeurs de pH cutané inchangées, a été démontrée. Une diminution de l'indice de mélanine a été mise en évidence également (après 7 jours, ΔMI était de 31,40 ± 16,50).

CONCLUSION

La crème cosmétique stabilisée par un émulsifiant conventionnel a montré un meilleur potentiel antioxydant et des effets d'hydratation et d'hypopigmentation plus faibles par rapport à la crème de même composition mais stabilisée par des émulsifiants biodégradables. D'après les données précédentes, la crème cosmétique étudiée pourrait être considérée comme un produit cosmétique moderne, stable, sûr et efficace dans la prévention et/ou le traitement des changements et/ou dommages cutanés liés au stress oxydatif, pour l'hydratation de la peau sèche, voire irritée, ainsi que pour éclaircir la peau hyperpigmentée.

Standardized extract of wild apple fruit in alkyl-polyglucoside-based cosmetic cream - estimation of stability, safety, antioxidant activity and efficiency

OBJECTIVE

The aim of this study was in vitro and in vivo characterization of cosmetic cream with 6% of wild apple fruit water extract, containing 3.5% of alpha-hydroxyacids-AHAs and polyphenolic compounds, stabilized by biodegradable alkyl-polyglucoside emulsifiers.

METHODS

In vitro characterization of cream included organoleptic and physico-chemical (pH values and electrical conductivity) analysis, antioxidant activity-AA estimation (using DPPH test) during 180 days of storage at 22±2°C and determination of cosmetic active substances content-AHAs (using HPLC analysis). In vivo estimation of skin irritation potential after creams application under occlusion during 24h was investigated employing the biophysical methods on 12 healthy volunteers; hydration efficiency, transepidermal water loss-TEWL, skin pH, erythema-EI and melanin index-MI on 10 healthy volunteers after 28 days of cream application and bleaching efficiency on 10 healthy volunteers after 7 days of cream application after artificially induced skin hyperpigmentation.

RESULTS

Investigated cosmetic cream was pale beige color, odorless, semi-solid consistency and homogeneous, with pH values of 6.53±0.14, electrical conductivity above 50 μS/cm and AA of 24.96%RSC after preparation and these characteristics were stable during investigated period. In vivo measurements revealed absence of skin irritation after cream application under occlusion, which was part of it's safety profile. Increase of skin hydration after 14 days of cream application was 17.28±12.23 and after 28 days 21.19±7.59. In addition, in performed experiment TEWL and skin pH values during cream application remained unchanged. Cream application after artificial hyperpigmentation induced decrease of MI (∆MI after 7 days was -45.30±18.55) CONCLUSION: Formulated cosmetic cream with 6% of standardized wild apple fruit water extract and stabilized by biodegradable alkyl-polyglucoside emulsifiers demonstrated good stability, acceptable level of in vitro antioxidant activity, absence of skin irritation after cream application under occlusion and positive effects of cream on human skin after application (hydrating and bleaching effects). All mentioned properties make the cream suitable for possible usage as cosmetic product for preventing the skin damages caused by oxidative stress, for moisturizing the dry skin and bleaching of skin hyperpigmentation. This article is protected by copyright. All rights reserved.

Formulation and characterization of monodisperse O/W emulsions encapsulating astaxanthin extracts using microchannel emulsification: Insights of formulation and stability evaluation

The study used straight-through microchannel emulsification (MCE) to encapsulate different extracts of astaxanthin (AXT) in oil-in-water (O/W) emulsion droplets. We used silicon microchannel plates (WMS 11-1) containing 13,752 discrete 10×104μm microslots, connected to a circular microhole with a diameter of 10μm. Two different AXT extracts (AstaReal (AR) and Zenthin^® (ZR)) based upon concentration and without purification was used as encapsulants in the dispersed phase, while different emulsifiers (1% (w/w) SDS, ML-750, MO-7S, Na-Cs and ML) with different stabilizing mechanisms were used as the continuous phase. The MCE was conducted at a dispersed phase flow rate of 1mLh^-1. Successful emulsification was conducted with a Sauter mean diameter of 35-37μm and relative span factor <0.25. The emulsification was highly depended on the type of emulsifiers and the extract type used during emulsification. Better droplet productivity was achieved with AR extract with 1% (w/w) ML-750 as the optimized emulsifier in Milli-Q Water. The O/W emulsion droplets remained stable at 25°C with encapsulation efficiency of over 98% during 15days of storage period.

Droplet Microfluidics for the Production of Microparticles and Nanoparticles

Droplet microfluidics technology is recently a highly interesting platform in material fabrication. Droplets can precisely monitor and control entire material fabrication processes and are superior to conventional bulk techniques. Droplet production is controlled by regulating the channel geometry and flow rates of each fluid. The micro-scale size of droplets results in rapid heat and mass-transfer rates. When used as templates, droplets can be used to develop reproducible and scalable microparticles with tailored sizes, shapes and morphologies, which are difficult to obtain using traditional bulk methods. This technology can revolutionize material processing and application platforms. Generally, microparticle preparation methods involve three steps: (1) the formation of micro-droplets using a microfluidics generator; (2) shaping the droplets in micro-channels; and (3) solidifying the droplets to form microparticles. This review discusses the production of microparticles produced by droplet microfluidics according to their morphological categories, which generally determine their physicochemical properties and applications.

One-pot preparation of poly(styrene-co-divinylbenzene)/silver nanoparticles composite microspheres with tunable porosity and their catalytic degradation of methylene blue in aqueous solution

Porous poly(styrene-co-divinylbenzene)/silver nanoparticle composite spheres with tunable porosity were synthesized by seed swelling polymerization method and show a great catalytic degradation of methylene blue within NaBH₄.

Formulation and characterization of esterified xylo-oligosaccharides-stabilized oil-in-water emulsions using microchannel emulsification

A series of amphiphilically esterified xylo-oligosaccharides (xylo esters) with different fatty acids residues - decanoic acid (C-10), lauric acid (C-12) and palmitic acid (C-16) - were enzymatically modified at 60°C for 4h. These xylo esters were used as emulsifiers to formulate oil-in-water (O/W) emulsions by microchannel emulsification (MCE). Grooved and straight-through MCE was used to investigate the droplet generation and/or emulsion stability. Xylo ester-stabilized oil droplets were generated smoothly from microchannels arranged linearly or two dimensionally, while xylo ester-stabilized emulsions were less monodispersed owing to low surface activity of the xylo esters. The combined use of xylo esters (2.5% (w/w)) and Tween series (0.1% (w/w)) in the continuous phase can improve the monodispersity of the resultant oil. Successful droplet generation was achieved with the straight-through MCE using 2.5% (w/w) xylo laurate and 0.1% (w/w) Tween 20. The optimized combination of xylo laurate and Tween 20 inhibited coalescence and oiling off more efficiently than the droplets solely stabilized by Tween 20 during 30days of storage.

Microencapsulation of Ascorbic Acid for Cosmetic by Utilizing Self-assembly of Phase Separated Polymer

Micrometer-sized polymer particles encapsulated ascorbic acid (vitamin C; VC) were successfully prepared by the three types of the self-assembling method, those are, phase separation and self-assembly of added polymer at the oil-water interface in emulsion, microsuspension polymerization utilizing the self-assembling of phase separated polymer (SaPSeP) method, and their hybrid method. In the stability study at 50°C for 2 months, the three kinds of capsule particles exhibited effective protection of VC from the interaction with other components in cosmetic consisting of water-in-oil (W/O) emulsion. The encapsulated VC was easily released from the capsule particles by an excess of water. These encapsulation methods will be useful for the stabilization of water-soluble substances in cosmetic consisting of W/O emulsion.

Monodisperse aqueous microspheres encapsulating high concentration of l-ascorbic acid: insights of preparation and stability evaluation from straight-through microchannel emulsification

Stabilization of l-ascorbic acid (l-AA) is a challenging task for food and pharmaceutical industries. The study was conducted to prepare monodisperse aqueous microspheres containing enhanced concentrations of l-AA by using microchannel emulsification (MCE). The asymmetric straight-through microchannel (MC) array used here constitutes 11 × 104 μm microslots connected to a 10 μm circular microholes. 5–30% (w/w) l-AA was added to a Milli-Q water solution containing 2% (w/w) sodium alginate and 1% (w/w) magnesium sulfate, while the continuous phase constitutes 5% (w/w) tetraglycerol condensed ricinoleate in water-saturated decane. Monodisperse aqueous microspheres with average diameters (dav) of 18.7–20.7 μm and coefficients of variation (CVs) below 6% were successfully prepared via MCE regardless of the l-AA concentrations applied. The collected microspheres were physically stable in terms of their dav and CV for &gt;10 days of storage at 40°C. The aqueous microspheres exhibited l-AA encapsulation efficiency exceeding 70% during the storage.

Formulation characteristics of triacylglycerol oil-in-water emulsions loaded with ergocalciferol using microchannel emulsification

Food grade monodisperse O/W emulsions encapsulating ergocalciferol have been formulated using microchannel emulsification. The O/W emulsion droplets have an encapsulation efficiency of over 75% within the evaluated storage period.