•Spontaneous thyme oil:ripening inhibitor nanoemulsions (d<70) were prepared.•Ripening inhibitors varied the degree of antimicrobial activity of nanoemulsions.•The antimicrobial efficacy correlated ...with the transfer of antimicrobial compounds.
The objective of this research was to study the impact of ripening inhibitor level and type on the formation, stability, and activity of antimicrobial thyme oil nanoemulsions formed by spontaneous emulsification. Oil-in-water antimicrobial nanoemulsions (10 wt%) were formed by titrating a mixture of essential oil, ripening inhibitor, and surfactant (Tween 80) into 5 mM sodium citrate buffer (pH 3.5). Stable nanoemulsions containing small droplets (d < 70 nm) were formed. The antimicrobial activity of the nanoemulsions decreased with increasing ripening inhibitor concentration which was attributed to a reduction in the amount of hydrophobic antimicrobial constituents transferred to the separated hydrophobic domain, mimicking bacterial cell membranes, by using dialysis and chromatography. The antimicrobial activity of the nanoemulsions also depended on the nature of the ripening inhibitor used: palm ≈ corn > canola > coconut which also depended on their ability to transfer hydrophobic antimicrobial constituents to the separated hydrophobic domain.
Fat plays multiple roles in determining the desirable physicochemical properties, sensory attributes, nutritional profile, and biologic response of food products. Overconsumption of fats is linked to ...chronic diseases, such as obesity, coronary heart disease, diabetes, and cancer. There is therefore a need to develop reduced-fat products with physicochemical properties and sensory profiles that match those of their full-fat counterparts. In addition, foods may be redesigned to increase the feelings of satiety and satiation, and thereby reduce overall food intake. The successful design of these types of functional foods requires a good understanding of the numerous roles that fat plays in determining food attributes and the development of effective strategies to replace these attributes. This article provides an overview of the current understanding of the influence of fat on the physicochemical and physiologic attributes of emulsion-based food products and highlights approaches to create high-quality foods with reduced-fat contents.
Probiotic microorganisms are incorporated into a wide variety of foods, supplements, and pharmaceuticals to promote human health and wellness. However, maintaining bacterial cell viability during ...storage and gastrointestinal transit remains a challenge. Encapsulation of bifidobacteria within food-grade hydrogel particles potentially mitigates their sensitivity to environmental stresses. In this study, Bifidobacterium longum subspecies and strains were encapsulated in core-shell microgels consisting of an alginate core and a microgel shell. Encapsulated obligate anaerobes Bifidobacterium longum subsp. infantis and Bifidobacterium longum subsp. longum exhibited differences in viability in a strain-dependent manner, without a discernable relationship to subspecies lineage. This includes viability under aerobic storage conditions and modeled gastrointestinal tract conditions. Coating alginate microgels with chitosan did not improve viability compared to cells encapsulated in alginate microgels alone, suggesting that modifying the surface charge alone does not enhance delivery. Thus hydrogel beads have great potential for improving the stability and efficacy of bifidobacterial probiotics in various nutritional interventions.
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The objective of this study was to provide insights into the mechanisms involved in the mass transport of antimicrobial compounds from essential oil nanoemulsions to bacterial cell ...membranes. Origanum oil-in-water nanoemulsions were produced using spontaneous emulsification by titrating a mixture of essential oil, ripening inhibitor, and surfactant (Tween 80) into 5 mM sodium citrate buffer (pH 3.5). Stable nanoemulsions containing relatively small droplets (d < 60 nm) were produced using this low-energy method. The nature of the ripening inhibitor used in the oil phase of the nanoemulsions affected the antimicrobial activity of the nanoemulsions: corn (LCT) > medium-chain triglycerides (MCT). Differences in antimicrobial activity were attributed to the differences in the rate of transfer of hydrophobic antimicrobial constituents from the nanoemulsion to the MCT emulsion, which was used to mimic the hydrophobic region of the bacterial cell membranes. Each antimicrobial nanoemulsion was separated from the MCT emulsion by a dialysis tubing. Dialysis tubing with two different pore sizes was used, one excluding nanoemulsion droplet and micelle delivery, allowing the delivery of antimicrobial compounds only through the aqueous phase and the other by both the aqueous phase and micelles. For origanum oil nanoemulsions, the delivery of all antimicrobial agents occurred more efficiently when micelles were present.
Lauric arginate (LAE) is a food-grade cationic surfactant that is a highly potent antimicrobial active against a wide range of food pathogens and spoilage organisms. In compositionally complex ...environments, the antimicrobial activity of cationic LAE is likely to be impacted by its interactions with other charged components. The purpose of this study was to characterize the interactions between cationic LAE and various food grade biopolymers with different charge characteristics: anionic (pectin, alginate, carrageenan, xanthan), neutral (dextran), and cationic (chitosan). Isothermal titration calorimetry (ITC) and turbidity measurements were used to characterize surfactant−biopolymer interactions and the solubility of any aggregates formed. ITC and turbidity measurements suggested that no complex formation occurred between the cationic LAE and the cationic or neutral biopolymers, although the critical micelle concentration (cmc) of the surfactant was changed because of excluded volume effects. On the other hand, ITC measurements indicated a strong binding interaction between cationic LAE and anionic biopolymers. The amount of surfactant bound and the solubility of the aggregates formed depended strongly on biopolymer type. The results of this study have important implications for the application of LAE in compositionally complex systems.
Nanoemulsion-based delivery systems are particularly effective tools for incorporating omega-3 polyunsaturated lipids into many foods and beverages. In this study, the impact of carrier oil type and ...concentration on the formation and stability of fish oil-in-water nanoemulsions was determined. Three carrier oils with different physicochemical and sensory properties were evaluated: medium chain triglycerides (MCT); lemon oil; and thyme oil. Nanoemulsions (d < 200 nm) were fabricated from oil phases containing lemon oil and MCT at all ratios with fish oil (0–100%), but only from thyme oil at high fish oil contents (75–100%). This effect was attributed to the high susceptibility of the nanoemulsions containing high levels of thyme oil to Ostwald ripening. Nanoemulsions fabricated from all carrier oils were physically stable (no increase in droplet size) during storage at 20 °C for 42 days when formulated from 75% fish oil and 25% carrier oil. However, carrier oil type did have an appreciable impact on the oxidative stability of these nanoemulsions, with the rate of lipid oxidation decreasing in the following order: MCT » lemon oil > thyme oil. This effect was attributed to the presence of high levels of natural antioxidants (phenolics) within the lemon and thyme oils. These results show that selection of an appropriate carrier oil type and concentration can lead to the formation of fish oil nanoemulsions with good physical and chemical stability.
•Carrier oil type and level affected fish oil nanoemulsion formation and stability.•Small droplets (d < 105 nm) could be formed with all carrier oils at 75% level.•Thyme oil could not form stable nanoemulsions when used at high levels.•Lipid oxidation rate depended on carrier oil type: MCT ≫ lemon oil > thyme oil.•This effect was attributed to natural antioxidants in the essential oils.
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•Conjugated linoleic acid (CLA) was encapsulated in food-grade O/W emulsions.•Interfacial complexes were formed by electrostatic deposition of pectin onto caseinate-coated ...droplets.•Emulsion stability was highly dependent on pH, ionic strength, and pectin level.•Increasing the pectin-to-caseinate ratio improved the pH stability of the emulsions.
Conjugated linoleic acid (CLA) may be used as a nutraceutical, supplement or pharmaceutical due to its potential health benefits. In this study, CLA oil-in-water emulsions were fabricated using biopolymers as stabilizers: sodium caseinate as an emulsifier and pectin as a coating material. The effect of electrostatic interactions on the formation of these mixed biopolymer coatings, as well as on the stability of the resulting emulsions, was determined by systematically varying pH and ionic strength. Caseinate-coated CLA droplets were stable from pH 7 to 5 due to the strong electrostatic repulsion between them, but aggregated from pH 5 to 3 due to weakening of the electrostatic repulsion near the protein’s isoelectric point. Pectin addition greatly improved emulsion aggregation stability, particularly at levels sufficient to saturate the caseinate-coated oil droplet surfaces. Indeed, emulsions with pectin-to-caseinate ratios>1:1 were stable under acidic solution conditions (pH 5 to 3). Ionic strength had a pronounced impact on droplet aggregation, which was pH dependent. At pectin-to-caseinate ratios of 2:1, emulsions were stable against NaCl addition (0 to 200mM) at pH 3.5 and 4.0 due to strong electrostatic attraction between protein and polysaccharide molecules in the interfacial complexes, but they were unstable to NaCl addition at pH 3.0, 4.5, and 5.0 due to a weaker electrostatic attraction between the biopolymers. Mixed biopolymer-coated emulsions were stable against thermal processing (90°C, 20min). These results have important implications for the development of natural CLA delivery systems for utilization in foods and other products.
The effect of stabilization of rice bran by domestic heating on mechanical extraction yield, quality and antioxidant properties of cold-pressed rice bran oil (RBO) was investigated. The highest ...extraction yield was found in hot air heating with 5.53 g/100 g bran, followed by microwave heating (4.81 g/100 g bran), roasting (4.77 g/100 g bran) and steaming (3.41 g/100 g bran). Hot air and microwave heating were the most effective methods for stabilization of rice bran (P < 0.05), which provided a low content of acid value (AV) 6.30–6.38 mg KOH/g oil, free fatty acid (FFA) 3.51–3.17% and peroxide value (PV) 11.72–12.13 mg Eqv/kg oil. Microwave and hot air heating stabilized RBO contained a higher content of total phenolic compounds than that of roasting and steaming stabilized RBO (P < 0.05). Hot air heating stabilized RBO had the highest content of gamma oryzanol but these were not significantly different in microwave and roasting stabilized RBO (P > 0.05). In conclusion, the stabilization of rice bran by domestic heating could be applied to RBO extraction prior to pressing to improve oil extraction yield, quality and antioxidant properties of cold-pressed RBO.
► Rice bran oil (RBO) has been used in many industries because of its unique properties. ► Rancidity of lipids in RBO is a major problem for utilization cold-pressed RBO. ► Domestic heating could improve yield, quality and antioxidant properties of cold pressed-RBO. ► Hot air and microwave heating were the most effective methods for stabilization of rice bran.
Radiopharmaceuticals serve as a major part of nuclear medicine contributing to both diagnosis and treatment of several diseases, especially cancers. Currently, most radiopharmaceuticals are based on ...small molecules with targeting ability. However, some concerns over their stability or non-specific interactions leading to off-target localization are among the major challenges that need to be overcome. Emulsion technology has great potential for the fabrication of carrier systems for radiopharmaceuticals. It can be used to create particles with different compositions, structures, sizes, and surface characteristics from a wide range of generally recognized as safe (GRAS) materials, which allows their functionality to be tuned for specific applications. In particular, it is possible to carry out surface modifications to introduce targeting and stealth properties, as well as to control the particle dimensions to manipulate diffusion and penetration properties. Moreover, emulsion preparation methods are usually simple, economic, robust, and scalable, which makes them suitable for medical applications. In this review, we highlight the potential of emulsion technology in nuclear medicine for developing targeted radionuclide therapies, for use as radiosensitizers, and for application in radiotracer delivery in gamma imaging techniques.
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