Surfactant-to-oil Ratio Research Articles

Fabrication of nanoemulsion delivery system with high bioaccessibility of carotenoids from Lycium barbarum by spontaneous emulsification.

The interest in incorporating carotenoids into foods and beverages is growing due to their potential health benefits. However, the poor water solubility and low bioavailability of carotenoids are still challenges in food application. This work aimed to study the influence of system composition and preparation conditions on the physical properties of carotenoids‐loaded nanoemulsions prepared by spontaneous emulsification. Furthermore, the bioaccessibility of carotenoids in the nanoemulsions was evaluated. The nanoemulsions with the smallest droplet size were produced when the ratio of Span 80:Tween 80 was 1.5:8.5. The droplet size increased slightly with the increase of organic phase content (24%–40%). The droplet size decreased gradually with the increase of stirring speed (200–1000 rpm (revolutions per minute)). The ratio of mixed surfactants and surfactant‐to‐oil ratio (SOR) had an appreciable impact on the droplet size. Carotenoids‐loaded nanoemulsions with small mean droplet size (d < 50 nm) could be prepared with the optimized conditions. The initial digestion rate decreased as the SOR increased. The bioaccessibility could reach up to about 80% at SOR=2–5 in vitro digestion. These results have important implications for the design of effective delivery systems to encapsulate carotenoids and other lipophilic bioactive components in food applications.

Physicochemical, antioxidant, antibacterial and antibiofilm activity of Carum copticum essential oil nanoemulsion on Escherichia coli O157:H7 and Listeria monocytogenes.

Carum copticum essential oil (CEO) is used to prevent the growth of food-borne pathogens. The Carum copticum essential oil nanoemulsion (CEON) was prepared using low energy sonication at 0, 2.50, 5.00 and 10 min based on surfactant to-oil ratio (SOR=1). Chemical composition, antimicrobial and antibiofilm properties of CEON were examined. Our data showed that the average diameter of the droplets of CEON was between 46.89 and 120.90 nm. The MICs of CEON and CEO against E. coli O157:H7 and L. monocytogenes were tested. L. monocytogenes was more sensitive than E. coli O157:H7. The sonication time and the total viable bacteria (TVC) in the study were inversely related to each other. Furthermore, CEON at the 4.00 × MIC concentration and contact time of 20 min caused 77.14% and 67.03% reduction of E. coli O157:H7 and L. monocytogenes biofilms, respectively. The antibiofilm activity of CEO was significantly lower than CEON and caused a 62.60% and 43.86% reduction of E. coli O157: H7 and L. monocytogenes biofilms, respectively. The results showed that CEON produced by low energy sonication would have a higher antibacterial efficiency than non-encapsulted essential oil.

Preparation of Tamanu Oil Nanoemulsions by Phase Inversion Temperature

In this study, the phase inversion temperature (PIT) method was used to prepare a stable tamanu oil nanoemulsion at the lowest surfactant content. The factors affecting the formation of nanoemulsions such as type of surfactant, surfactant to oil ratio (SOR), and water content were investigated. The results showed that Tween 80 is suitable for making a stable nanoemulsion. The SOR is more than or equal to 1.5:1 produced emulsions with particle size less than 100 nm. The particle size decreased as SOR, and water content increased. A higher quantity of surfactant caused higher turbulence and affinity towards the aqueous phase, resulting in smaller droplets. Decreasing droplet size by increasing water content may result from a decreased viscosity of the surfactant at the interface that promotes fluidity and the easy movement of the oil phase towards the aqueous phase. The SOR of 3:1 and water content of 80% were selected due to cost, taste, and toxicity concerns. The impact of storage condition on nanoemulsion stability was also investigated. After one month, samples were stored in the refrigerator had an insignificant increase in absorbance. Particle size analysis also showed a similar result (< 20 nm).

Developing a Highly Stable Carlina acaulis Essential Oil Nanoemulsion for Managing Lobesia botrana.

The growing interest in the development of green pest management strategies is leading to the exploitation of essential oils (EOs) as promising botanical pesticides. In this respect, nanotechnology could efficiently support the use of EOs through their encapsulation into stable nanoformulations, such as nanoemulsions (NEs), to improve their stability and efficacy. This technology assures the improvement of the chemical stability, hydrophilicity, and environmental persistence of EOs, giving an added value for the fabrication of natural insecticides effective against a wide spectrum of insect vectors and pests of public and agronomical importance. Carlina acaulis (Asteraceae) root EO has been recently proposed as a promising ingredient of a new generation of botanical insecticides. In the present study, a highly stable C. acaulis-based NE was developed. Interestingly, such a nanosystem was able to encapsulate 6% (w/w) of C. acaulis EO, showing a mean diameter of around 140 nm and a SOR (surfactant-to-oil ratio) of 0.6. Its stability was evaluated in a storage period of six months and corroborated by an accelerated stability study. Therefore, the C. acaulis EO and C. acaulis-based NE were evaluated for their toxicity against 1st instar larvae of the European grapevine moth (EGVM), Lobesia botrana (Denis & Schiffermüller, 1775) (Lepidoptera: Tortricidae), a major vineyard pest. The chemical composition of C. acaulis EO was investigated by gas chromatography–mass spectrometry (GC–MS) revealing carlina oxide, a polyacetylene, as the main constituent. In toxicity assays, both the C. acaulis EO and the C. acaulis-based NE were highly toxic to L. botrana larvae, with LC50 values of 7.299 and 9.044 µL/mL for C. acaulis EO and NE, respectively. The C. acaulis-based NE represents a promising option to develop highly stable botanical insecticides for pest management. To date, this study represents the first evidence about the insecticidal toxicity of EOs and EO-based NEs against this major grapevine pest.

Optimization of Mangifera indica L. Kernel Extract-Loaded Nanoemulsions via Response Surface Methodology, Characterization, Stability, and Skin Permeation for Anti-Acne Cosmeceutical Application.

This study aimed to optimize nanoemulsions loading with Mangifera indica L. kernel extract using response surface methodology for enhancing the stability and skin permeation of the extract. Central composite design was employed for optimization and evaluation of three influencing factors including hydrophile-lipophile balance (HLB), % co-surfactant (PEG-7 glyceryl cocoate), and surfactant-to-oil ratio (SOR) on physical properties of the nanoemulsions. The desired nanoemulsions were then incorporated with the extract and characterized. Physicochemical properties of the extract-loaded nanoemulsions and their antibacterial effects against Propionibacterium acnes were also evaluated after storage at various conditions and compared to those of the initial. Ex vivo skin permeation was also investigated. The factors significantly (p < 0.05) influenced on droplet size, polydispersity index (PDI), and zeta potential, especially HLB of the surfactant and its combined effects with co-surfactant and SOR. The extract-loaded nanoemulsions revealed a very small spherical droplets (size of 26.14 ± 0.22 nm) with narrow size distribution (PDI of 0.16 ± 0.02). The formulation also presented an excellent stability profile and successfully enhanced antibacterial stability of the extract comparing with the extract solution. Ex vivo skin permeation study illustrated that the extract in nanoemulsions could be delivered through a primary skin barrier to reach viable epidermis dermis layers. In conclusion, the affinity of surfactant and hydrophilicity of the system play a crucial role in nanoemulsions’ characteristics. Such results might provide promising anti-acne nanoemulsions with the notable capacities of extract stabilization and permeation enhancing which will be further clinically evaluated.

Formulation, characterization and stability of o/w nanoemulsion containing rice bran oil prepared by emulsion phase inversion

Rice bran oil (RBO) contains naturally occurring antioxidants such as carotenoids, tocopherol, and γ-oryzanol. The aim of this research was to formulate and evaluate the characteristics of nanoemulsion which was prepared using RBO containing naturally occurring antioxidants. The RBO-in-water nanoemulsion was prepared by the emulsion phase inversion method. The oil phase of the nanoemulsion was prepared by either virgin coconut oil (VCO) or palm oil (PO) combined with RBO with the ratio of 5:5; 4:6, 3:7, 2:8 and 0:10. Tween 80 was used as a surfactant. The surfactant to oil ratios was predetermined at 2.5:1.0 and 3.0:1.0. The aqueous phase (80% w/w) was titrated into an organic phase that consisted of Tween 80 and oil phase (approximately 20% w/w). Droplet size, zeta-potential and polydispersity index of the nanoemulsion were used as the main parameters. The results showed that the smallest droplet (&lt;100 nm) of the nanoemulsion was obtained when the ratio of VCO: RBO at 3:7 and the ratio of PO: RBO at 4:6 with the surfactant to oil ratio (SOR) was 2.5. Nanoemulsion with a relatively small polydispersity index of 0.3 was achieved when the ratio of PO: RBO was 3:7 and SOR at 3. All of the freshly prepared RBO containing nanoemulsion have good stability with zetapotential values of &lt; -30 mV. Nanoemulsions were stable against centrifugation at 2300 rpm for 15 mins, but they were not stable against heating at 105°C for 5 hrs. The RBO-inwater nanoemulsion could be successfully prepared by phase inversion method, by combining RBO with either VCO or PO at different ratios.

Factors affecting the formation of highly concentrated emulsions and nanoemulsions

Highly concentrated (HC) emulsions and or submicron emulsions arise as an interesting strategy to encapsulate and transport labile lipophilic bioactive compounds such as curcumin to be further incorporated into food formulations. The main factors affecting HC-emulsions formation and stabilization are the homogenization process, the oil volume fraction (φ) and the surfactant to oil ratio (SOR). Therefore, different HC emulsions were prepared by high-shear homogenization (HSH; 11,000 rpm, 2 min), ultrasonication (US; 100 μm, 20–300 s) or microfluidization (MF; 800 bar, 1–5 cycles) varying the φ from 0.4 to 0.7 (40%–70% w/w) and the SOR from 0.01 to 0.2. HSH led to HC emulsions, whose particle sizes decreased from 14.46 to 2.42 μm (d43), as the φ increased from 0.4 to 0.7. However, US and MF provoked the droplet breakup at oil concentrations over 50% w/w. Additionally, the higher the SOR at a fixed φ, the smaller the particle size of the resultant HC emulsions regardless the homogenization procedure applied. Overall, particle size reduction produced a dramatic increase in emulsion viscosity due to a high packing state of droplets that in turn prevented droplets re-coalescence. Moreover, HC emulsions presented a high curcumin encapsulation efficiency (>70%) and release (> 80% after 48 h is). Therefore, this work contributes to demonstrate that the small droplets size is governing the apparent viscosity in HC systems, as well as to elucidate the factors affecting their formation to be used as potential carriers of lipophilic bioactive compounds.

Lipid nanoparticles with fats or oils containing β-carotene: Storage stability and in vitro digestibility kinetics.

The aim of this work was to study the formation of lipid nanoparticles (LNPs) with low (corn and olive oil) or high temperature melting lipids (cocoa butter and hydrogenated coconut oil). Moreover, their β-carotene stability and in vitro digestibility kinetics was evaluated. Submicron LNPs (d43 ≈ 570-780 nm) were stabilized with Tween 80 at a surfactant-to-oil ratio (SOR) of 0.1. It was reduced below 200 nm at an SOR of 1. The β-carotene retention at 25 °C was not related to the lipid type but rather to the particle size, being lower in samples with smaller particle sizes. Cocoa butter LNPs presented an equally complete digestion as corn oil LNPs and a high β-carotene bioaccessibility, which was related to the high degree of micellarization of monoacylglycerols. This work evidences the potential of LNPs to protect lipophilic bioactive compounds with a high digestibility and bioaccessibility.

Comparative study on lipid digestion and carotenoid bioaccessibility of emulsions, nanoemulsions and vegetable-based in situ emulsions

Emulsions (d43 0.484–0.897 μm) and nanoemulsions (d43 0.279–0.226 μm) based on lipid fractions enriched with carotenoids from different sources were produced by increasing the amount of a non-ionic surfactant (Tween 80) at surfactant-to-oil ratio (SOR) 0.1 or 2, respectively. Alternatively, carrot purée in situ emulsions were fabricated by processing carrot purée with a non-enriched oil fraction and Tween 80 (SOR 0.1). Emulsions, nanoemulsions and in situ emulsion were subjected to in vitro digestion conditions with focus on the kinetics of lipid digestion, micelle formation and carotenoid bioaccessibility during the small intestinal phase. Nanoemulsions produced with a high amount of surfactant showed an almost complete lipid hydrolysis inhibition probably due to hindered lipase adsorption at oil-water interfaces. Emulsions presented a gradual lipid digestion during the intestinal phase and subsequent incorporation of lipid digestion products into mixed micelles. Interestingly, the in situ emulsion presented a similar lipid digestion trend than emulsions, yet a lower concentration of lipid digestion products incorporated into mixed micelles, which resulted in a lower carotenoid bioaccessibility. Overall, this study highlights the potential of using nanoemulsions to modulate lipid digestion. Moreover, it also indicates possible interactions between food components and lipid digestion products during the formation of mixed micelles and its implications on the bioaccessibility of lipophilic bioactives such as carotenoids.

Preparation of Nanoemulsion from Sacha Inchi Oil/Water by Emulsion Phase Inversion Methods

The aim of this study was to develop a nanoemulsion of Sacha inchi oil for cosmetic application by the emulsion phase inversion (EPI) method. The influence of surfactant type and surfactant-to-oil ratio (SOR) on the particle size distributions of the nanoemulsion was studied. The results obtained showed that nanoemulsion droplet size, and stability of nanoemulsions were varied considerably. At optimal condition, the smallest size (41.43 ± 0.12 nm.) and high zeta potential values were obtained

Formation of oil-in-water emulsions from natural emulsifiers using spontaneous emulsification: sunflower phospholipids.

This study examined the possibility of producing oil-in-water emulsions using a natural surfactant (sunflower phospholipids) and a low-energy method (spontaneous emulsification). Spontaneous emulsification was carried out by titrating an organic phase (oil and phospholipid) into an aqueous phase with continuous stirring. The influence of phospholipid composition, surfactant-to-oil ratio (SOR), initial phospholipids location, storage time, phospholipid type, and preparation method was tested. The initial droplet size depended on the nature of the phospholipid used, which was attributed to differences in phospholipid composition. Droplet size decreased with increasing SOR and was smallest when the phospholipid was fully dissolved in the organic phase rather than the aqueous phase. The droplets formed using spontaneous emulsification were relatively large (d > 10 μm), and so the emulsions were unstable to gravitational separation. At low SORs (0.1 and 0.5), emulsions produced with phospholipids had a smaller particle diameter than those produced with a synthetic surfactant (Tween 80), but at a higher SOR (1.0), this trend was reversed. High-energy methods (microfluidization and sonication) formed significantly smaller droplets (d < 10 μm) than spontaneous emulsification. The results from this study show that low-energy methods could be utilized with natural surfactants for applications for which fine droplets are not essential.

Organogel-nanoemulsion containing nisin and D-limonene and its antimicrobial activity.

The aim of this study was to investigate a novel delivery system containing D-limonene and nisin by food organogel-nanoemulsion and study its effect on the antimicrobial activity. Organogel-nanoemulsion containing with D-limonene and nisin or without nisin was prepared by a homogenization method. Factors that may affect the droplet size and stability of organogel-nanoemulsion such as pressure and surfactant to oil ratio (SOR) were studied. The average droplet size decreased with pressure, and the organogel-nanoemulsion could achieve good stability at low SOR. Positive effects and outstanding antimicrobial activities of organogel-nanoemulsion containing with D-limonene and nisin were confirmed by minimal inhibitory concentrations comparison, growth curves of bacteria, scanning electron microscopy and determination of cell constituents’ release. Furthermore, the organogel-nanoemulsion applied as food preservative in milk also shown excellent antimicrobial performance. Overall, the research described in the current article show that organogel-nanoemulsion containing with D-limonene and nisin may be an effective antimicrobial system for the production and preservation of food.

Low-energy formation of edible nanoemulsions by spontaneous emulsification: Factors influencing particle size

Nanoemulsions are used as delivery systems in food, pharmaceutical, and personal care applications for a variety of lipophilic active components, e.g., antimicrobials, flavors, colors, preservatives, vitamins, nutraceuticals, and drugs. In this study, we examined the effect of system composition and preparation conditions on the production of edible nanoemulsions using spontaneous emulsification (SE). SE is a low-energy method that simply involves addition of an organic phase (oil+surfactant) into an aqueous phase. The influence of surfactant-to-oil ratio (SOR), surfactant type, surfactant location, and oil type were tested. The droplet size produced decreased with increasing SOR, and was smallest when the non-ionic surfactant Tween 80 was used. Smaller droplets were formed when the surfactant was initially dispersed in the oil phase rather than the aqueous phase. Ten food-grade oils were tested and we found that droplet size followed the order: medium chain triglycerides<flavor oils<long chain triglycerides. No correlation was found between droplet size and the physicochemical characteristics of the oil phase (refractive index, density, interfacial tension, and viscosity). Results obtained by spontaneous emulsification were correlated to those obtained by emulsion phase inversion on similar systems suggesting a common underlying physicochemical mechanism.

Fabrication of Lipophilic Nanoparticles by Spontaneous Emulsification: Stabilization by Cosurfactants

Lipid nanoparticles are increasingly being used to encapsulate and deliver lipophilic bioactive components in food, pharmaceutical, and personal care products. These nanoparticles can be produced by high-energy or low-energy methods, with the latter approach having advantages in terms of simplicity, lower energy demands, and reduced production costs. In this study, a model system consisting of non-ionic surfactant (Brij 30), hydrocarbon oil (n-octadecane) and aqueous phase (citric acid buffer, pH 3.0) was used to examine the impact of cosurfactants on the stability of nanoemulsions produced by spontaneous emulsification. Initially, the optimum surfactant-to-oil ratio (SOR) for preparing nanoemulsions with small droplets was established: SOR = 0.5. In the absence of cosurfactants, the surfactant-oil–water (SOW) system formed by spontaneous emulsification contained large irregular structures (>10 μm) that remained after dilution. However, addition of cosurfactants (SDS or Tween 80) to the SOW system promoted the formation of nanoemulsions (d < 100 nm) that were stable to droplet growth. The nanoemulsions also had good thermal stability when SDS was used as a cosurfactant (25–90 °C), but underwent rapid coalescence above 50 °C when Tween 80 was used. This study suggests that cosurfactants improve the stability of nanoemulsions by disrupting the formation of liquid crystal like structures and altering the phase inversion temperature.

Formation of vitamin D nanoemulsion-based delivery systems by spontaneous emulsification: Factors affecting particle size and stability

Oil-in-water nanoemulsions are particularly suitable for encapsulation of lipophilic nutraceuticals because of their ability to form stable and transparent delivery systems with high oral bioavailability. In this study, the influence of system composition and preparation conditions on the particle size and stability of vitamin D nanoemulsions prepared by spontaneous emulsification (SE) was investigated. SE relies on the formation of small oil droplets when an oil/surfactant mixture is titrated into an aqueous solution. The influence of oil phase composition (vitamin D and MCT), surfactant-to-oil ratio (SOR), surfactant type (Tween 20, 40, 60, 80 and 85), and stirring conditions on the initial particle size of vitamin D nanoemulsions was studied. Nanoemulsions with small droplet diameters (d<200nm) could be formed using Tween 80 at SOR⩾1 at high stirring speeds (800rpm). These systems were relatively stable to droplet growth at ambient temperatures (<10% in diameter after 1month storage), but unstable to heating (T>80°C). The thermal stability of the nanoemulsions could be improved by adding a cosurfactant (sodium dodecyl sulphate (SDS)). The spontaneous emulsification method is simple and inexpensive to carry out and therefore has great potential for forming nanoemulsion-based delivery systems for food, personal care, and pharmaceutical applications.

Optimization of isothermal low-energy nanoemulsion formation: Hydrocarbon oil, non-ionic surfactant, and water systems

Nanoemulsions can be fabricated using either high-energy or low-energy methods, with the latter being advantageous because of ease of implementation, lower equipment and operation costs, and higher energy efficiency. In this study, isothermal low-energy methods were used to spontaneously produce nanoemulsions using a model system consisting of oil (hexadecane), non-ionic surfactant (Brij 30) and water. Rate and order of addition of surfactant, oil and water into the final mixture were investigated to identify optimal conditions for producing small droplets. The emulsion phase inversion (EPI) and spontaneous emulsion (SE) methods were found to be the most successful, which both require the surfactant to be mixed with the oil phase prior to production. Order of addition and surfactant-to-oil ratio (SOR) influenced the particle size distribution, while addition rate and stirring speed had a minimal effect. Emulsion stability was strongly influenced by storage temperature, with droplet size increasing rapidly at higher temperatures, which was attributed to coalescence near the phase inversion temperature. Nanoemulsions with a mean particle diameter of approximately 60nm could be produced using both EPI and SE methods at a final composition of 5% hexadecane and 1.9% Brij 30, and were relatively stable to droplet growth at temperatures <25°C.

Nanoemulsion-Based Delivery Systems for Polyunsaturated (ω-3) Oils: Formation Using a Spontaneous Emulsification Method

Nanoemulsion-based delivery systems are finding increasing utilization to encapsulate lipophilic bioactive components in food, personal care, cosmetic, and pharmaceutical applications. In this study, a spontaneous emulsification method was used to fabricate nanoemulsions from polyunsaturated (ω-3) oils, that is, fish oil. This low-energy method relies on formation of fine oil droplets when an oil/surfactant mixture is added to an aqueous solution. The influence of surfactant-to-oil ratio (SOR), oil composition (lemon oil and MCT), and cosolvent composition (glycerol, ethanol, propylene glycol, and water) on the formation and stability of the systems was determined. Optically transparent nanoemulsions could be formed by controlling SOR, oil composition, and aqueous phase composition. The spontaneous emulsification method therefore has considerable potential for fabricating nanoemulsion-based delivery systems for incorporating polyunsatured oils into clear food, personal care, and pharmaceutical products.

Behavior of vitamin E acetate delivery systems under simulated gastrointestinal conditions: Lipid digestion and bioaccessibility of low-energy nanoemulsions

Colloidal delivery systems are needed to incorporate oil-soluble vitamins into aqueous-based foods and beverage products. In this study, we encapsulated vitamin E acetate into oil-in-water nanoemulsions produced using either a low-energy method (Emulsion Phase Inversion, EPI) or a high energy method (microfluidization). Oil-in-water nanoemulsions (d<200nm) could be produced using both low- and high-energy methods from a non-ionic surfactant (Tween 80) and medium chain triglycerides (MCTs). The influence of surfactant-to-oil ratio (SOR) on lipid digestion and vitamin bioaccessibility of EPI nanoemulsions was determined using a gastrointestinal tract (GIT) model that simulated the mouth, stomach, and small intestine. There were increases in the size and negative charge of the oil droplets after passage through the GIT, which was attributed to droplet coalescence and changes in interfacial composition. The rate and extent of lipid digestion decreased with increasing surfactant concentration, but the bioaccessibility of vitamin E acetate was high in all of the samples (>95%). No appreciable influence of the preparation method (low-energy versus high-energy) on lipid digestion and vitamin bioaccessibility was observed. The major advantage of the EPI method for forming nanoemulsions is that no expensive equipment is required, but relatively high surfactant concentrations are needed compared to microfluidization.

Vitamin E-enriched nanoemulsions formed by emulsion phase inversion: Factors influencing droplet size and stability

There is considerable interest in using nanoemulsions as delivery systems for lipophilic bioactive ingredients, such as oil-soluble vitamins. Nanoemulsions can be fabricated using either high-energy or low-energy methods, but the latter offer advantages in terms of low cost, higher energy efficiency, and simplicity of implementation. In this study, the emulsion phase inversion (EPI) method was used to produce food-grade nanoemulsions enriched with vitamin E acetate. The EPI method simply involves titrating water into a mixture containing oil and surfactant, which initially leads to the formation of a water-in-oil emulsion that then inverts into an oil-in-water emulsion. Oil composition, surfactant type, and surfactant-to-oil ratio (SOR) were all found to influence the particle size distribution of the systems produced. Nanoemulsions with a mean particle diameter of 40nm could be produced at a final system composition of 2wt% MCT, 8wt%vitamin E acetate, and 20wt% Tween 80. The EPI method was shown to be unsuitable for producing nanoemulsions from label-friendly surfactants, such as Quillaja saponin, whey protein, casein, and sucrose monoesters. The EPI method was more effective at producing nanoemulsions at high SOR than microfluidization, but much less effective at low SOR.

Low-energy formation of edible nanoemulsions: Factors influencing droplet size produced by emulsion phase inversion

Nanoemulsions can be used for the encapsulation and oral delivery of bioactive lipophilic components, such as nutraceuticals and pharmaceuticals. There is growing interest in the utilization of low-energy methods to produce edible nanoemulsions. In this study, we examined the influence of system composition and preparation conditions on the formation of edible nanoemulsions by the emulsion phase inversion (EPI) method. The EPI method involves titrating an aqueous phase (water) into an organic phase (oil+hydrophilic surfactant). The influence of oil type, surfactant type, surfactant-to-oil ratio (SOR), and initial surfactant location on the particle size distributions of the emulsions was studied. The droplet size produced by this method depended on: (i) oil type: medium chain triglycerides (MCT)<flavor oils (orange and limonene)<long chain triglycerides (olive, grape, sesame, peanut and canola oils); (ii) surfactant type: Tween 80<Tween 20<Tween 85; (iii) surfactant concentration: smaller droplets were produced at higher SOR; (iv) surfactant location: surfactant initially in oil<surfactant initially in water. The low energy method (EPI) was also compared to a high energy method (microfluidization). Small droplets (d<160nm) could be produced by both methods, but much less surfactant was needed for the high energy method (SOR⩾0.1) than the low energy method (SOR⩾0.7).