Edible films including active ingredients can be used as an alternative to preserve food products. Essential oils (EOs) exhibit antimicrobial activity against pathogenic microorganisms but their low ...water solubility limits the application in foods. To improve water dispersion and protect EOs from degradation, nano-sized emulsions emerge as a viable alternative. Nanoemulsions containing EOs and polysaccharides could be used to form edible films with functional properties. This study was focused on the evaluation of physical, mechanical and antimicrobial properties of alginate-based edible films formed from nanoemulsions of EOs. Nanoemulsions containing thyme (TH-EO), lemongrass (LG-EO) or sage (SG-EO) oil as dispersed phase and sodium alginate solution as continuous phase were prepared. The average droplet size of nanoemulsions was reduced after the microfluidization treatment exhibiting multimodal size distributions. The ζ-potentials of nanoemulsions were between −41 mV and −70 mV depending on the type of EO used. The lowest whiteness index was found in SG-EO nanoemulsions, whereas those containing TH-EO showed the highest value. Films formed from SG-EO nanoemulsions exhibited higher transparency, water vapor resistance and flexibility than films formed from TH-EO or LG-EO. Edible films containing TH-EO were those with the strongest antimicrobial effect against inoculated Escherichia coli, achieving up to 4.71 Log reductions after 12 h. Results obtained in the present work evidence the suitability of using nanoemulsions with active ingredients for the formation of edible films, with different physical and functional properties.
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•Nanoemulsions with very small oil droplet size were produced by microfluidization.•Alginate-based edible films from nanoemulsions containing essential oils were formed.•Oil droplet size and droplet charge of nanoemulsions determined edible film properties.•Antimicrobial activity of films was governed by oil type rather than oil droplet size.
This study explores developing and optimizing a nanoemulsion (NE) system loaded with dipyridamole and roflumilast, aiming to improve skin penetration and retention. The NE formulation was further ...transformed into a nanoemulgel to enhance its application as a topical treatment for psoriasis. Solubility studies were conducted to select the oil, surfactant, and co-surfactant. Phase diagrams were constructed using the aqueous phase titration method. All the formulations were in nanoscale, and Formula (F2) (which contains oleic acid oil as the oil phase, a mixture of Surfactant Tween 80 and co-surfactant (ethanol) at a ratio of 1:2 in addition to distilled water as an aqueous phase in a ratio of 1:5:4, respectively) was the selected formula depending on the particle size, PDI, and zeta potential. Formula (F2) has the best ratio because it gives the smallest nanoemulsion globule size (particle size average of 167.1 nm), the best homogenicity (lowest PDI of 0.195), and the highest stability (higher zeta potential of −32.22). The selected formula was converted into a nanoemulgel by the addition of 0.5% (w/w) xanthan gum (average particle size of 172.7 nm) and the best homogenicity (lowest PDI of 0.121%) and highest stability (higher zeta potential of −28.31). In conclusion, the selected formula has accepted physical and chemical properties, which enhanced skin penetration.
Natural aldehydes, such as cinnamaldehyde, can be used to modify the properties of chitosan-based materials by covalent cross-linking the chitosan molecules. Due to the non-polarity and ...hydrophobicity of cinnamaldehyde, emulsification technique was used to prepare homogeneous cinnamaldehyde-chitosan films. Under optimized conditions, cinnamaldehyde nanoemulsions led to the successful fabrication of uniform and smooth chitosan films. FTIR analysis of the films indicated the formation of chitosan-cinnamaldehyde Schiff base. The cross-linked films strongly absorbed UV–visible light and inhibited the emission of fluorescent light, and may therefore provide good photo-protection. The thickness (26–61 μm) and transparency (clear to turbid) of the chitosan films were modulated by varying the aldehyde/amino group ratio. The mechanical properties and water vapor permeability of the films also depended on the amount of cinnamaldehyde nanoemulsion utilized. Chitosan films showed good antimicrobial activity, but had better antifungal than antibacterial activity.
The content of cinnamaldehyde-loaded nanoemulsion modulated the surface and cross-section structure of crosslinked chitosan films. Display omitted
•Active chitosan films were prepared by cross-linking with cinnamaldehyde nanoemulsions.•Cross-linked chitosan films showed good UV barrier properties.•The surface morphology of chitosan films showed granular structure.
Nanoemulsions have small droplet size and are kinetically stable colloidal systems. They have enhanced functional properties in comparison to conventional emulsions. The composition and structure of ...the nanoemulsions can be controlled for the encapsulation and effective delivery of bioactive lipophilic compounds. Nanoemulsions have potential application in the food industry for the delivery of nutraceuticals, coloring and flavoring agents, and antimicrobials. The nanoemulsion formulations of active ingredients can be used for developing biodegradable coating and packaging films to enhance the quality, functional properties, nutritional value, and shelf life of foods. This review focuses on preparation of food grade nanoemulsions using high-energy methods and low-energy approaches and their characterization for physical properties, stability, and microstructure. The application of nanoemulsion formulations for sustainable food processing and improving the delivery of functional compounds, such as colorants, flavoring agents, nutraceuticals, and preservatives or antimicrobial agents in foods has been discussed.
•Pickering nanoemulsion formulation and characterization have been reviewed.•EOR mechanisms during Pickering nanoemulsion flooding have been analyzed.•The key operational factors and their impacts ...have been highlighted.•The key limitations and obstacles still faced by the process have been discussed.•Proposals for future research to address the unresolved challenges are included.
The key mechanisms in enhancing crude oil recovery include the reduction of interfacial tension (IFT) between the trapped crude oil and the injected flooding solution, the wettability alteration of the reservoir rocks, in-situ emulsification, pore plugging, mobility control, disjoining and capillary pressures, miscibility improvement, etc. Recently, Pickering nanoemulsions have emerged as attractive flooding fluids that can positively alter all the above mechanisms and, thus, provide an improved oil recovery relative to other tertiary methods. The nanoparticles (NPs) used to stabilize Pickering nanoemulsions must be carefully selected and engineered in order to impart the desired characteristics (e.g., stability, emulsion type, droplet size, zeta potential, etc.). Yet, the relationship between the efficacy of Pickering nanoemulsions in enhancing oil recovery and their characteristics is very complex and not fully understood. Additionally, the oil recovery enhancement mechanisms are quite complex and governed by several interrelated factors. Therefore, this article provides a state-of-the-art review of the formulations and applications of Pickering nanoemulsions for enhancing the recovery of crude oil, with a focus on the recovery mechanisms. Relevant recent studies on the topic have been analyzed and assessed in order to provide insights into the achieved progress and to highlight the remaining obstacles and challenges. Future research work to address the key obstacles and challenges has been proposed.
Rheology is a powerful and versatile analytical tool for providing information about changes in the composition, structure, and interactions of food emulsions. Moreover, an understanding of emulsion ...rheology is essential for designing efficient food processing operations and emulsion‐based foods with the desired physicochemical, sensory, and nutritional attributes, such as appearance, texture, flavor, shelf life, and bioavailability. This article provides a brief overview of the current understanding of food emulsions, with a focus on how their viscosity is related to the properties of the emulsion droplets present.
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•Curcumin, the major bioactive material turmeric, has wide range of biological features.•Curcumin exhibits a poor water solubility and low chemical stability.•Nanoemulsions delivery ...systems have been used to improve functional properties of curcumin.•The generation of nanoemulsions can be achieved through different preparation technologies.
Curcumin is widely acknowledged for its beneficial activities. However, its application has remained challenging due to its low aqueous solubility, biochemical/structural degradation and poor bioavailability. For these reasons, many researches are aimed at overcoming these limitations using lipid-based nanosystems to encapsulate curcumin, especially nanoemulsions. This review highlights the theoretical aspects and recent advances of preparation technologies (phase inversion temperature, phase inversion composition, ultrasonication, high pressure homogenization and microfluidization) for encapsulation of curcumin in nanoemulsions. Additionally, the specific factors in designing nanoemulsions systems that affect the chemical stability and in vitro bioaccessibility of the encapsulated curcumin are discussed. Also, the importance of nanoemulsions in improving antioxidant, anti-inflammatory and anticancer activities of curcumin is underlined. Curcumin-loaded nanoemulsions preparation technologies have been proposed to provide efficient, systematic, and practical protocols for improved applications of curcumin. Additionally, key factors that influence curcumin delivery include the nature of emulsifier, the type and the amount of carrier oil and emulsifier-curcumin interactions. The pharmacological activities of curcumin including antioxidant, anti-inflammatory and anticancer activities can be improved by nanoemulsions.
Curcumin is a natural antioxidant dye that has a wide spectrum of biological activities (e.g., anti-cancer, anti-hypertensive, anti-inflammatory and neuroprotective activities), and there is a high ...interest within the food industry to increase its use as a natural additive. However, due to its high hydrophobicity, it is difficult to incorporate into aqueous formulations and its bioavailability can be severely decreased. Lipid-based encapsulation systems such as nanoemulsions can help to overcome both of these drawbacks. In this study, curcumin-loaded nanoemulsions were produced by the emulsification inversion point method, for which some of the operational parameters were optimized. The most stable formulations were composed of 20% soybean oil, 10% Tween 80 and 20% glycerol and were produced with an anchor blade impeller operating at 300 rpm; this combination of parameters resulted in 0.07% encapsulation of the curcumin. After 60 days, 70% of the initial amount of curcumin remained in the nanoemulsions, which is a promising result when compared with those of other lipid-based encapsulation systems. The data also indicated that the catastrophic phase inversion occurred due to the formation of multiple o/w/o emulsions.
•Nanoemulsions with average diameter of 200 nm were produced by emulsion inversion point method.•Scalable process conditions (mechanical stirring and aqueous flow pumping) were optimized.•Glycerol as cosolvent was necessary for the production of nanoemulsions by the EIP method.•Nanoemulsions protected curcumin for a period longer than usually found in the literature.
Summary
Many human acid tolerant bacterial and fungal pathogens can be transmitted through the consumption of the contaminated fruit juices. We aim to formulate essential oil nanoemulsions (basil, ...black seed, turmeric, clove & cinnamon), determine their ability to clear contamination by food borne bacterial pathogens from fruit juices. The antibacterial activity of the optimised formulations was tested in the fruit juices against bacterial pathogens causing gastrointestinal tract infections. The minimum bactericidal concentration (MBC) of clove emulsions ranged from 15.6 to 25 μL mL−1. Cinnamon oil emulsion had an MBC ranging between 15 and 31 μL mL−1. At MBC, cinnamon oil emulsions caused a 6log10 decrease in viable counts by 8 h and maintained the sterility of fruit juices for 7 days at ambient temperature. Thus, clove and cinnamon microemulsions can be used as juice additives to control food borne bacterial pathogens and maintain the bacterial sterility of fruit juices.
Antibacterial activity of essential oils in contaminated fruit juices.
The production of safe foods with little or no artificial preservatives is one of the foremost leading challenges for food manufacturing industries because synthetic antimicrobial agents and chemical ...food additives can cause severe negative effects on human health. However, there is an ever-increasing interest by consumers towards natural sources that have been aroused recently, and this increased consumer demand for safe food products has forced the food industries to use natural herbal and plant origins preservatives instead of synthetic preservatives for the production of safe foods. Traditionally, essential oils (EOs) obtained from numerous plant sources have been extensively encouraged for their putative health-promoting biological activities. The EOs are composed of complex mixtures encompassing copious individual compounds, which have been extracted by many methods. These diverse compounds display significant biological activities such as antioxidant and antimicrobial through different mechanisms. Nevertheless, their poor solubility in water, oxidation susceptibility, and volatility limit their use. To overcome these constraints, encapsulation is one of the best approaches to preserve the biological activities of EOs and minimize their effects on food sensory qualities. Herein, we have comprehensively enlightened the micro/nanoemulsion loaded with EOs to improve the physical—chemical and microbiological stability of various EOs, and further application of these EOs loaded systems in the food systems. This review confers the importance of EOs in terms of their main components, chemical and biological properties, including mode of action, effectiveness, synergistic effects as antimicrobials, and potential applications in the food system as a preservative.
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