Understanding mechanisms behind the oily mouthcoating perception of pure vegetable oils using tribology.

Tribology is the science of measuring friction between surfaces. While it has been widely used to investigate texture sensations of food applications, it is seldom applied in pure edible oil systems. In this research, we measured friction, viscosity, and solid fat content (SFC) of nine vegetable oils at 30 and 60°C.

Cereal bran protects vitamin A from degradation during simmering and storage.

Food supplementation with vitamin A is an efficient strategy to combat vitamin A deficiency. The stability of vitamin A during cooking and storage is, however, low. We here show that cereal bran protects retinyl palmitate (RP) during simmering and storage.

Nature-Inspired Design and Application of Lipidic Lyotropic Liquid Crystals.

Amphiphilic lipids aggregate in aqueous solution into a variety of structural arrangements. Among the plethora of ordered structures that have been reported, many have also been observed in nature. In addition, due to their unique morphologies, the hydrophilic and hydrophobic domains, very high internal interfacial surface area, and the multitude of possible order-order transitions depending on environmental changes, very promising applications have been developed for these systems in recent years.

Vitamin A degradation in triglycerides varying by their saturation levels.

Vitamin A deficiency has a widespread occurrence globally and is considered as one of the world's most serious health risk factors. Potential solutions to address this deficiency include dietary diversification or supplementation, but food fortification is generally accepted as the most cost-effective solution. The main issue with food fortification of this vitamin is related to its high instability in food matrices.

Strategies to limit colour changes when fortifying food products with iron.

Iron, vitamin A, zinc and iodine have been recognized to be the micronutrients with the largest deficiencies worldwide. Among these, iron is highly reactive and may lead to negatively perceived organoleptic changes in products such as dull colour and off-taste. The colour change originated in fortified fruit-containing food products was confirmed to be the result of the complexation of iron and polyphenols.

Direct visualization of dispersed lipid bicontinuous cubic phases by cryo-electron tomography.

Bulk and dispersed cubic liquid crystalline phases (cubosomes), present in the body and in living cell membranes, are believed to play an essential role in biological phenomena. Moreover, their biocompatibility is attractive for nutrient or drug delivery system applications. Here the three-dimensional organization of dispersed cubic lipid self-assembled phases is fully revealed by cryo-electron tomography and compared with simulated structures.

Oil and drug control the release rate from lyotropic liquid crystals.

The control of the diffusion coefficient by the dimensionality d of the structure appears as a most promising lever to efficiently tune the release rate from lyotropic liquid crystalline (LLC) phases and dispersed particles towards sustained, controlled and targeted release. By using phosphatidylcholine (PC)- and monolinoleine (MLO)-based mesophases with various apolar structural modifiers and water-soluble drugs, we present a comprehensive study of the dimensional structural control of hydrophilic drug release, including 3-d bicontinuous cubic, 2-d lamellar, 1-d hexagonal and 0-d micellar cubic phases in excess water. We investigate how the surfactant, the oil properties and the drug hydrophilicity mitigate or even cancel the effect of structure variation on the drug release rate.

Oil transfer converts phosphatidylcholine vesicles into nonlamellar lyotropic liquid crystalline particles.

There is a need for the development of low-energy dispersion methods tailored to the formation of phospholipid-based nonlamellar lyotropic liquid crystalline (LLC) particles for delivery system applications. Here, facile formation of nonlamellar LLC particles was obtained by simple mixing of a phosphatidylcholine (PC) liposome solution and an oil-in-water emulsion, with limonene or isooctane as an oil. The internal structure of the particles was controlled by the PC-to-oil ratio, consistently with the sequence observed in bulk phase.

Facile dispersion and control of internal structure in lyotropic liquid crystalline particles by auxiliary solvent evaporation.

Submicron sized, structured lyotropic liquid crystalline (LLC) particles, so-called hexosomes and cubosomes, are generally obtained by high energy input dispersion methods, notably ultrasonication and high-pressure emulsification. We present a method to obtain dispersions of such LLC particles with a significantly reduced energy input, by evaporation of an auxiliary volatile solvent immiscible with water, e.g.

Viscoelasticity and interface bending properties of lecithin reverse wormlike micelles studied by diffusive wave spectroscopy in hydrophobic environment.

Upon the addition of minute quantities of water into a phosphatidylcholine (PC) solution in certain organic solvents, PC micelles elongate into giant reverse wormlike micelles that entangle and form highly viscous microemulsions, called lecithin organogels. We investigated the microrheological properties of concentrated PC-cyclohexane reverse wormlike micellar systems by diffusive wave spectroscopy (DWS) in apolar medium, combined with bulk shear rheology. We applied DWS to our oil-continuous system by using hydrophobic poly(hydroxystearic acid)-grafted PMMA particles as monodisperse tracer particles.

Vitamin E and vitamin E acetate absorption from self-assembly systems under pancreas insufficiency conditions.

We determined the bioavailability of vitamin E from self-assembly structures in patients with diagnosed chronic pancreas insufficiency. Vitamin E solubilized in dispersed inverted bicontinuous cubic phase and in micellar formulation was delivered directly to the small intestine by tube-feeding. A cross-over study with randomization of 6 subjects and 2 treatments including a combined dose of 18 mg (27 IU) of vitamin E (RRR-[5,7-methyl-((2)H6)]-α-tocopherol) and 27 mg (27 IU) vitamin E acetate (RRR-[5-methyl-(2)H3]-α-tocopheryl acetate) was applied over a time period of 1 h.

Phospholipid-based nonlamellar mesophases for delivery systems: bridging the gap between empirical and rational design.

Phospholipids are ubiquitous cell membrane components and relatively well-accepted ingredients due to their natural origin. Phosphatidylcholine (PC) in particular offers a promising alternative to monoglycerides for lyotropic liquid crystalline (LLC) delivery system applications in the food, cosmetics and pharmaceutical industries, provided its strong tendency to form zero-mean curvature lamellar mesophases in water can be overcome. Higher negative curvatures are usually reached through the addition of a third lipid component, forming a ternary diagram phospholipid/water/oil.

A reverse micellar mesophase of face-centered cubic Fm3m symmetry in phosphatidylcholine/water/organic solvent ternary systems.

We report the formation of a reverse micellar cubic mesophase of symmetry Fm3m (Q(225)) in ternary mixtures of soy bean phosphatidylcholine (PC), water, and an organic solvent, including cyclohexane, (R)-(+)-limonene, and isooctane, studied by small-angle X-ray scattering (SAXS) and oscillatory shear rheology at room temperature. The mesophase structure consists of a compact packing of remarkably large reverse micelles in a face-centered cubic (fcc) lattice, a type of micellar packing not yet reported for reverse micellar mesophases. Form factor fitting in the pure L2 phase and in the Fm3m-L2 coexistence region yields quantitative estimations of the PC interface rigidity.

Self-assembled structures and pKa value of oleic acid in systems of biological relevance.

In the human digestion process, triglycerides are hydrolyzed by lipases to monoglycerides and the corresponding fatty acids. Here we report the self-assembly of structures in biologically relevant, emulsified oleic acid-monoolein mixtures at various pH values and oleic acid concentrations. Small-angle X-ray scattering, cryogenic transmission electron microscopy, and dynamic light scattering were used to investigate the structures formed, and to follow their transitions while these factors were varied.

Influence of the stabilizer concentration on the internal liquid crystalline order and the size of oil-loaded monolinolein-based dispersions.

The internal phase of monolinolein-based dispersions loaded with tetradecane or (R)-(+)-limonene was investigated as a function of the stabilizer content by small-angle X-ray scattering. Phase transitions at the colloidal scale were found in some of nanostructured aqueous dispersions by increasing the stabilizer content. For particles containing a bicontinuous cubic phase, a large increase of the stabilizer concentration promoted a liquid crystalline phase transition from the Pn3m to the Im3m cubic symmetry.

Monocomponent hexa- and dodecaethylene glycol succinyl-tocopherol esters: self-assembly structures, cellular uptake and sensitivity to enzyme hydrolysis.

We have chemically synthesized two water-soluble forms of tocopherol succinate linked via an ester bond to hexaethylene glycol and dodecaethylene glycol. The self-assembly structure of the former in water is vesicular, whereas the latter forms elongated micelles. We treated Caco-2 cells with these compounds in these physical forms, in addition to a mixed micelle form.

Internally self-assembled thermoreversible gelling emulsions: ISAsomes in methylcellulose, kappa-carrageenan, and mixed hydrogels.

Self-assembled thermo-gelling emulsions were developed by blending internally self-assembled particles (ISAsomes) with thermoreversible polysaccharide hydrogels of methylcellulose (MC), kappa-carrageenan (KC), and their 1:1 mixture. In this way, the hierarchical structure of ISAsome samples was successfully promoted. The gelified polymer network corresponds to the highest level of the hierarchical structure and as such represents the capturing matrix for the medium structural level, i.

Internally self-assembled particles entrapped in thermoreversible hydrogels.

The present study describes the development of thermogelling emulsions by the entrapment of internally self-assembled emulsion droplets (ISAsomes) within a thermoreversible hydrogel made of kappa-carrageenan. The droplets are emulsified mesophases of cubic or hexagonal order, or emulsified micro-emulsions. Above 60 degrees C, the system was fluid and composed of a mixture of internally nanostructured small droplets and polymer chains dispersed in water.

Delayed volatile compound release properties of self-assembly structures in emulsions.

Temporal release and retention of aroma compounds from structured emulsions (where unsaturated monoglycerides are added to the oil) and conventional oil-in-water emulsions were studied using in vitro dynamic headspace analysis by proton-transfer reaction mass spectrometry and static headspace analysis by gas chromatography-mass spectrometry. Under dynamic conditions, the structured emulsion exhibited delayed release compared to the oil-in-water emulsion containing the same lipid content of 5%. The time to maximum concentration T max of amphiphilic and lipophilic aroma compounds increased by a factor of 1.

Study of liquid crystal space groups using controlled tilting with cryogenic transmission electron microscopy.

We developed a method that enables differentiation between liquid crystalline-phase particles corresponding to different space groups. It consists of controlled tilting of the specimen to observe different orientations of the same particle using cryogenic transmission electron microscopy. This leads to the visualization of lattice planes (or reflections) that are present for a given structure and absent for the other one(s) and that give information on liquid crystalline structures and their space groups.

Structural and rheological investigation of Fd3m inverse micellar cubic phases.

In the present study we demonstrate that a bulk inverse micellar cubic phase of Fd3m structure can be obtained by adding a hydrophobic component, such as the food-grade limonene, to the binary system monolinolein/water in a well-defined composition. The Fd3m structure studied in this work had a very slow kinetics of formation, as a consequence of partitioning of water into two types of micelle populations with different sizes. The Fd3m structure formed at a ratio of limonene oil to total lipids of alpha = 0.

Model studies on the release of aroma compounds from structured and nonstructured oil systems using proton-transfer reaction mass spectrometry.

Relative retention, volatility, and temporal release of volatile compounds taken from aldehyde, ester, and alcohol chemical classes were studied at 70 degrees C in model systems using equilibrium static headspace analysis and real time dynamic headspace analysis. These systems were medium-chain triglycerides (MCT), sunflower oil, and two structured systems, i.e.

Control of the internal structure of MLO-based isasomes by the addition of diglycerol monooleate and soybean phosphatidylcholine.

This work describes the effect of two different surfactants on the internal nanostructure of the kinetically stabilized isasomes (internally self-assembled particles or "somes"), which are a new family of colloidal particles (cubosomes, hexosomes, micellar cubosomes, and emulsified microemulsions, EME). The stabilization of these systems is performed by using the polymeric stabilizer F127. We demonstrate that the internal structure of these oil-free and oil-loaded dispersed particles can be modulated by varying the lipid composition.

Self-assembly of polar food lipids.

Polar lipids, such as monoglycerides and phospholipids, are amphiphilic molecules commonly used as processing and stabilization aids in the manufacturing of food products. As all amphiphilic molecules (surfactants, emulsifiers) they show self-assembly phenomena when added into water above a certain concentration (the critical aggregation concentration). The variety of self-assembly structures that can be formed by polar food lipids is as rich as it is for synthetic surfactants: micelles (normal and reverse micelles), microemulsions, and liquid crystalline phases can be formulated using food-grade ingredients.

Oil-loaded monolinolein-based particles with confined inverse discontinuous cubic structure (Fd3m).

In our recent work, we reported on the effect of varying temperature and solubilizing tetradecane (TC) on the structural transitions observed in dispersed particles based on the monolinolein (MLO)-water-TC system. At a given temperature, the addition of TC induces a transition of the internal structure from the bicontinuous cubic phase, Pn3m, to the reversed hexagonal, H2, and to the isotropic liquid phase (water-in-oil (W/O) microemulsions). Our present study focuses on the discovery of a Fd3m phase (reversed discontinuous micellar cubic), which is formed in the MLO-water-TC system at a specific TC/MLO weight ratio.