In this study, the capability of a natural surfactant, lecithin, and the influence of ionic strength, pH, and temperature on some properties of a food grade microemulsion system were evaluated. For this purpose, the pseudoternary phase diagrams of canola oil/lecithin:n-propanol/water microemulsions in the presence of different salts (NaCl and CaCl2), ionic strengths, pHs, and temperatures were constructed. Our findings showed that the presence of salts slightly increased the W/O areas on the phase diagrams, whereas pH variation was not effective on the microemulsion formation. The expansion of microemulsion areas with temperature indicated the greater triglycerides solubilization capacity of lecithin based microemulsions at higher temperatures. These findings revealed the efficiency of lecithin-based microemulsion system for solubilization of triglycerides which can potentially be used for extraction of edible vegetable oils particularly canola oil.

Unheated and heat-aggregated β-lactoglobulin (β-lg) solutions were used to stabilize clove oil-in-water emulsion and limonene-in-water emulsion prepared by microchannel (MC) emulsification. The size of the MC array plate was 15 × 15 mm2 consisting of 100 parallel MCs fabricated on each side of the plate. The channels were 4 μm depth, 71 μm length, and 8.2 μm width, with the terrace length of 29.1 μm. Unheated and heat-aggregated β-lg effectively stabilized clove oil-in-water and limonene-in-water emulsions during production using MC emulsification. The emulsion droplets were steadily produced by the channels. The average diameter of clove oil droplets was around 17 μm, with both unheated and heat-aggregated β-lg, regardless of the concentration of β-lg. The average diameter of the limonene droplets was 18–26 μm depending on the conditions (unheated or heat-aggregated) and the concentration of β-lg. The coefficient of variation for all average droplet diameters was ≤8%, which was an indication of monodisperse droplets. Clove oil-in-water emulsion droplets became polydisperse within 2 h observation, whilst limonene-in-water emulsion droplets remained monodisperse over time. The stability of the oil droplets over time related to the solubility of the oil phases rather than the effects of β-lg as the surfactant. In addition, the droplet sizes at different surfactant concentrations seemed to relate to the viscosity ratio between the dispersed phase and the continuous phase rather than the effects of the surfactant.

The microstructure and stability of oil-in-water emulsions, stabilized with non-protein emulsifiers (sorbitan esters), were analyzed as a function of emulsification time, rotor speed, hydrophilic-lipophilic balance (HLB), and ionic strength. Sauter average dia (D[3,2]) were determined from micrographs. Back-scattered light data were analyzed and a method to determine creaming rates of the systems was proposed. Creaming rates showed that the relationship between emulsion stability and HLB was non-linear. Addition of NaCl raised creaming rates, resulting in decreased stability, while micrographs showed the presence of flocs. Results were discussed taking account of interactions present in the system.

Polyglycerol polyricinoleate (PGPR) was used as the oil-soluble surfactant and beeswax was used as the oil phase to formulate a water-in-oil (W/O) high internal phase emulsions (HIPEs) for the encapsulation and protection of probiotics. The physicochemical properties of the W/O HIPEs and the survival of the encapsulated probiotics when exposed to acidic conditions and in vitro digestion were investigated. The viability of the probiotics decreased slightly when exposed to high-speed shearing. The rheological analysis, microstructural images, physicochemical stability showed that the W/O HIPEs remained relatively stable. The survival of the probiotics loaded in the SK-HIPEs (prepared with skim milk) was much higher than in the NS-HIPEs (prepared with normal saline) during storage at 4 °C. An in vitro gastrointestinal model showed that encapsulation of the probiotics enhanced their survival. This study provides useful insights into the utilization of W/O HIPEs to improve the efficacy of probiotics in the food industry.

This review article demonstrates fundamentals regarding the manufacturing of multilayer oil-in-water (M-O/W) emulsions and factors affecting stability of these systems. Moreover, characteristics of major bioactive lipophilic components and ingredients mostly applied to form multilayered membranes as well analytical methods used to examine properties of M-O/W emulsions are specified. It has been shown that production of M-O/W systems is based on the layer-by-layer (LbL) electrostatic deposition technique which makes use of the electrostatic attraction of oppositely charged surfactants and biopolymers to form multicomposite protective layers around emulsion droplets. Finally, limitations regarding studies of M-O/W systems which should be developed are specified.

Health benefits are associated with polyunsaturated fatty acids, but their sensitivity to oxidation may generate toxic oxidation species. The objective of this study was to compare the effect of milk proteins (casein, whey protein) and surfactants (Citrem, Tween 20) on the in vitro digestion and oxidation of linseed oil emulsions. The emulsion produced with Tween 20 resisted coalescence in the gastric phase and showed the highest concentrations of free fatty acids and reactive carbonyl compounds in the intestinal digestion phase. The Citrem-stabilized emulsion showed extensive coalescence in the gastric environment, which reduced lipolysis and the formation of advanced oxidation species. The protein-stabilized emulsions showed aggregation with some coalescence in the gastric phase, and casein provided better protection than whey protein against oxidation. This study suggests that the mechanism of emulsion destabilization in the gastric environment and the type of protein can modulate lipolysis and oxidation during in vitro digestion.

There is growing demand for functional food products enriched with long chain omega-3 polyunsaturated fatty acids (LCω3PUFA). Nanoemulsions, systems with extremely small droplet sizes have been shown to increase LCω3PUFA bioavailability. However, nanoemulsion creation and processing methods may impact on the oxidative stability of these systems. The present systematic review collates information from studies that evaluated the oxidative stability of LCω3PUFA nanoemulsions suitable for use in functional foods. The systematic search identified seventeen articles published during the last 10 years. Researchers used a range of surfactants and antioxidants to create systems which were evaluated from 7 to 100 days of storage. Nanoemulsions were created using synthetic and natural emulsifiers, with natural sources offering equivalent or increased oxidative stability compared to synthetic sources, which is useful as consumers are demanding natural, cleaner label food products. Equivalent vegetarian sources of LCω3PUFA found in fish oils such as algal oils are promising as they provide direct sources without the need for conversion in the human metabolic pathway. Quillaja saponin is a promising natural emulsifier that can produce nanoemulsion systems with equivalent/increased oxidative stability in comparison to other emulsifiers. Further studies to evaluate the oxidative stability of quillaja saponin nanoemulsions combined with algal sources of LCω3PUFA are warranted.

Nanoemulsions are of great interest in food industry finding various food applications. However, oil-in-water (o/w) nanoemulsions have been intensively investigated, but there are few studies on w/o nanoemulsions. In the present work the preparation of nanoemulsions with olive oil using non-ionic surfactants (Tween 20, 40, 60, 80, Span 20, 80) without the addition of a co-surfactant was studied and their emulsion properties and stability were examined. The stable nanoemulsions were presented in ternary phase diagrams (oil–water-surfactant) for each surfactant and the emulsifying ability of the efficient surfactants was determined. The nanoemulsions properties were evaluated in relationship to compositional components. From the results of this study it can be concluded that stable olive oil nanoemulsions without use of a co-surfactant were obtained and moreover the most efficient type of emulsifier and its ratio of addition in the system were determined.

BACKGROUND: Sugar‐based surfactants are highly relevant alternative ingredients for food grade formulations. Nevertheless, the design of sustainable manufacturing processes is still ongoing. RESULTS: Sorbitol ester surfactants were synthesized by lipase‐catalyzed esterification in solvent‐free conditions. Octanoic acid was dispersed in a 70 wt% sorbitol aqueous solution (containing the enzyme). The maximal conversion of 23.5 mole % of esterified fatty acid per mole of loaded fatty acid was obtained after 48 h in optimal conditions. The performance of the reactor was affected by both the nature and amount of the reactants and the dispersion state. Detailed structural analysis demonstrated that lipase from Candida rugosa specifically catalyzed the acylation of sorbitol on primary hydroxyl groups. Sorbitol esters accumulated exclusively in the oil phase, which led to easy and efficient product recovery. Oil phase containing the sorbitol esters could be used directly for preparing oil‐in‐water nanoemulsion without adding any other stabilizer. These nanoemulsions exhibited good stability after 7 days storage at 25°C or 60°C. CONCLUSION: A green manufacturing process for food grade oil‐in‐water nanoemulsions was designed involving a lipase‐catalyzed esterification step which produced in situ the required surfactant. Nanoemulsions were prepared without using any other stabilizer. © 2017 Society of Chemical Industry

A new kind of solid phase extraction (SPE), which we named in situ surfactant-based solid phase extraction (ISS-SPE), represents a simple, selective and rapid method for preconcentration and determination of manganese from food and water samples. This method has distinct advantages: extraction times are short and recoveries are high; further, we can see formation of fine particles of large specific surface and their good dispersion in the solution. In this work, a small amount of cationic surfactant, n-dodecyltrimethylammonium bromide (DTAB) was injected into the water sample containing Mn ions, which were complexed by 1-(2-pyridylazo)-2-naphthol (PAN). After shaking, a little volume of NaPF6 as an ion-pairing agent was added into the solution by a microsyringe. After preconcentration, the settled phase was dissolved in a specific volume of ethanol and then aspirated into the flame atomic absorption spectrometer by using a homemade microsample introduction system. The effective parameters such as pH, concentration of surfactant, concentration of chelating agent, concentration of ion-pairing agent and effect of salt concentration were optimized by a fractional factorial design to identify the most important parameters and their interactions, and central composite methodology was used to achieve the optimum point of effective parameters to the response. Under the optimum conditions, preconcentration of 10 ml of the sample solution permitted detection of 0.88 μg l−1 with enhancement factor of 45.6, and the relative standard deviation (RSD) for five determinations of Mn ions was 3.5%. The developed method was applied to the determination of trace manganese in various real samples with satisfactory results.