Lipophilic Deviation Research Articles

Electrochemically driven emulsion inversion

It is shown that emulsions stabilized by ionic surfactants can be inverted by controllingthe electrical potential across the oil–water interface. The potential dependentpartitioning of sodium dodecyl sulfate (SDS) was studied by cyclic voltammetry at the1,2-dichlorobenzene|water interface. In the emulsion the potential control was achieved by using a potential-determiningsalt. The inversion of a 1,2-dichlorobenzene-in-water (O/W) emulsion stabilized by SDSwas followed by conductometry as a function of added tetrapropylammonium chloride. Asudden drop in conductivity was observed, indicating the change of the continuous phasefrom water to 1,2-dichlorobenzene, i.e. a water-in-1,2-dichlorobenzene emulsion wasformed. The inversion potential is well in accordance with that predicted by thehydrophilic–lipophilic deviation if the interfacial potential is appropriately accountedfor.

Formulation–composition map of a lecithin-based emulsion

Formulation–composition map is an interesting tool to predict the nature of an emulsion, stability, viscosity and nevertheless to decide the mixing protocol of its ingredients. Information based on optimum formulation (environmental conditions at which the affinity of an emulsifier for oil and for aqueous phase is same), which is depicted through hydrophilic–lipophilic deviation (HLD) concept, is necessary to make a formulation–composition map of an emulsion. In order to apply this concept in food emulsions, it is necessary to determine characteristic constants of each component of the system, i.e. the aqueous phase, the oil phase and the emulsifier at equilibrium. In this work formulation–composition map of a sunflower oil–water–lecithin system, based on the knowledge of phase behavior of lecithin at equilibrium and emulsification, was made. The shape of inversion line on formulation–composition map was not the classical stair type rather an almost vertical inversion line at water-fraction ( f w) near 0.20 was observed. It was supposed to be linked to the viscosity of oil phase which was 50 times the viscosity of aqueous phase. Additionally, emulsions were of oil-in-water (O/W) type for f w higher than 0.20, but their viscosity and the drop size behavior with respect to salt concentration as formulation variable did not show the existence of transitional inversion line on formulation–composition map. Such map in advance can certainly facilitate the guidelines for dynamic emulsification.

Spectrophotometric method associated with formulation scans for application of hydrophilic–lipophilic deviation concept in food emulsions

Hydrophilic–lipophilic deviation (HLD) concept is well developed in the fields of cosmetics, pharmaceutics and enhanced oil recovery and therefore, it is adopted for emulsification process in a predictive and controlled way. To apply this concept, it is necessary to get the knowledge of optimum formulation (i.e. emulsion's environmental parameters at which the affinity of emulsifier for aqueous and oil phase is equal) through formulation scans. In above fields optimum formulation of the oil–water–emulsifier system is commonly detected through simple techniques like visual observation, light scattering, and interfacial tension measurements. Unfortunately, such techniques are not suitable for food emulsion systems, because of the complexities associated with the emulsifiers and vegetable oils. This study deals with the detection of optimum formulation (formulation scan with respect to salt concentration) of food grade emulsion system through spectrophotometric assay of emulsifier molecule in the aqueous and oil phase, and in microemulsion. It is shown that the spectrophotometric method associated with formulation scans is a relatively more accurate method to detect optimum formulation. This method was studied with a model system which resembles to a mayonnaise, i.e. sunflower oil–water–lecithin. Spectrophotometric method associated with formulation scans put forward a better understanding of transitional inversion which is pre-requisite to make a formulation–composition map of an emulsion system.

A novel criterion for studying the phase equilibria of non‐ionic surfactant–triglyceride oil–water systems

AbstractThe formulation of macro‐ and microemulsions through the Hydrophilic Lipophilic Deviation (HLD) concept based on phase behaviour observations, has mostly been applied to mineral oils. The present research reports a similar approach using triglyceride‐based oils (seven vegetable oils and one pure triglyceride) and ethoxylated (nonylphenol and isotridecanol) surfactant systems. Formulation scans are carried out by varying the surfactant average degree of ethoxylation, eg the ethylene oxide number (EON), at 50 °C, 55 °C and 60 °C. Because these systems do not exhibit a Winsor III phase behaviour, the so‐called optimum formulation was detected for EON0.5, ie the EON value at which the surfactant partitions equally into the aqueous and the oil phases, which was found to coincide with the minimum stability of the emulsified systems. Experimental EON0.5 values ranged from 3.5 to 5.5 as temperature, oil nature and surfactant were altered.© 2003 Society of Chemical Industry

Application of hydrophilic–lipophilic deviation formulation concept to microemulsions containing pine oil and nonionic surfactant

AbstractThe phase behaviour at 25 °C of surfactant‐oil‐water systems containing pine oil and commercial ethoxylated isotridecanols (nonionic surfactants) is reported. All Winsor phase behaviour types were observed, depending on the surfactant average Ethylene Oxide Number and concentration. The technique used was based on the occurrence of the so‐called optimum formulation at which a bicontinuous microemulsion phase is in equilibrium with excess water and oil, with an associated minimum in interfacial tension. Optimum formulation was found at a zero value of the hydrophilic–lipophilic deviation (HLD), a numerical expression which takes all formulation variables into account. This HLD relationship was used to determine the Equivalent Alkane Carbon Number (EACN) of pine oil and its major components.© 2003 Society of Chemical Industry

HLD concept as a tool for the characterization of cosmetic hydrocarbon oils

AbstractThe HLD (hydrophilic lipophilic deviation) concept was applied to several water/i‐C13En/2‐propanol/hydrocarbon oil systems. For each oil, the optimum formulation, corresponding to HLD = 0, was determined by systematically changing the formulation as a monotonic variation of the surfactant ethylene oxide number (EON) scanned variable. The optimum value for EON (symbolized as EON*) was accurately pinpointed both by estimating the solubilization and by measuring the interfacial tension with a spinning‐drop tensiometer. This method allowed the classification of cosmetic hydrocarbon oils such as isohexadecane, paraffin oil, squalane, squalene and hydrogenated polydecenes in C30, C40, C40–C50, on an equivalent alkane carbon number (EACN) calibration scale based on five linear alkanes covering the liquid range (C5 to C16).© 2003 Society of Chemical Industry

The emergence of formulation engineering in emulsion making—transferring know‐how from research laboratory to plant

AbstractAll variables capable of altering the physico‐chemical formulation, including temperature, are included in a generalized concept known as the hydrophilic–lipophilic deviation (HLD), which measures the departure from the reference state at which the surfactant–oil–water system exhibits Winsor III three‐phase behaviour. The general phenomenology representing the emulsion properties (type, stability, viscosity, drop size) can be qualitatively charted in a three‐dimensional map, where each region exhibits definite features. Travelling across the map from one region to another corresponds to modifications in formulation, composition and stirring along a path which can describe the protocol of change in an industrial process dealing with emulsion making, inversion or reworking. Six different path cases, labelled as unit operations, emerge from a systematic categorizing, and allow the interpretation of complex industrial processes such as crude oil dehydration, or the manufacturing of paint, cosmetics or heavy hydrocarbon emulsions.© 2003 Society of Chemical Industry