Nanostructuring fiber morphology and solvent inclusions in 12-hydroxystearic acid / canola oil organogels

Soy Protein Isolate Gel Subjected to Freezing Treatment: Influence of Methylcellulose and Sodium Hexametaphosphate on Gel Stability, Texture and Structure

Freezing affects texture and induces the loss of gel quality. This study investigated the effects of methylcellulose (MC) (0.2%, 0.4%, 0.6%) and sodium hexametaphosphate (SHMP) (0.15%, 0.3%) on the gel textural and structural properties of SPI gels before and after freezing, and explores the synergistic enhancement of gel texture and the underlying mechanisms resulting from the simultaneous addition of SHMP and MC to SPI gels. It was revealed that MC improved the strength of SPI gels through its thickening properties, but it could not inhibit the reduction of SPI gels after freezing. The 0.4% MC-SPI gel exhibited the best gel strength (193.2 ± 2.4 g). SHMP inhibited gel reduction during freezing through hydrogen bonding and ionic interactions; it enhanced the freezing stability of SPI gels. The addition of 0.15% SHMP made the water-holding capacity in SPI gels reach the highest score after freezing (58.2 ± 0.32%). The synergistic effect of MC and SHMP could improve the strength and the freezing stability of SPI gels. MC facilitated the release of ionizable groups within SPI, causing negatively charged SHMP groups to aggregate on the SPI and inhibit the freezing aggregation of proteins. These results provide a strong basis for the improvement of cryogenic soy protein gel performance by SHMP and MC.

A comprehensive review: Impact of oleogel application on food texture and sensory properties

Oleogels, characterized by their semisolid matrix formed from liquid oil structured by gelators, are emerging as a pivotal innovation in food formulation, primarily due to their capacity to enhance the nutritional profile of products by incorporating healthier fats. This review explored the integration of oleogels into diverse food matrices, examining their impact on texture, mouthfeel, and overall sensory characteristics. Through an extensive analysis of current research, this paper illustrates the versatility of oleogels created with a variety of structuring agents across different food applications. It also addresses the challenges inherent in the use of oleogels, including the preservation of their stability and consistency through varying storage and processing conditions, navigating the regulatory landscape concerning oleogelator safety and acceptability, and confronting higher production costs. Overall, this comprehensive review highlights the potential of oleogels as a promising tool for achieving desirable textural and sensory attributes in food products while also identifying areas for future research and development.

Recent Advances in Lipid Crystallization in the Food Industry

This review discusses fundamental concepts of fat crystallization and how various processing conditions such as crystallization temperature, cooling rate, and shear or agitation affect this process. Traditional methods used to process fats, such as the use of scraped surface heat exchangers, fractionation, and interesterification, are described. Parameters that affect fat crystallization in these systems, such as shear, crystallization temperature, type of fat, and type of process, are discussed. In addition, the use of minor components to induce or delay fat crystallization based on their chemical composition is presented. The use of novel technologies, such as high-intensity ultrasound, oleogelation, and high-pressure crystallization is also reviewed. In these cases, acoustic and high-pressure process parameters, the various types of oleogels, and the use of oleogelators of differing chemical compositions are discussed. The combination of all these techniques and future trends is also presented.

Organogels: "GelVolution" in Topical Drug Delivery - Present and Beyond

Topical drug delivery holds immense significance in dermatological treatments due to its non-invasive nature and direct application to the target site. Organogels, a promising class of topical drug delivery systems, have acquired substantial attention for enhancing drug delivery efficiency. This review article aims to explore the advantages of organogels, including enhanced drug solubility, controlled release, improved skin penetration, non-greasy formulations, and ease of application. The mechanism of organogel permeation into the skin is discussed, along with formulation strategies, which encompass the selection of gelling agents, cogelling agents, and additives while considering the influence of temperature and pH on gel formation. Various types of organogelators and organogels and their properties, such as viscoelasticity, non-birefringence, thermal stability, and optical clarity, are presented. Moreover, the biomedical applications of organogels in targeting skin cancer, anti-inflammatory drug delivery, and antifungal drug delivery are discussed. Characterization parameters, biocompatibility, safety considerations, and future directions in optimizing skin permeation, ensuring long-term stability, addressing regulatory challenges, and exploring potential combination therapies are thoroughly examined. Overall, this review highlights the immense potential of organogels in redefining topical drug delivery and their significant impact on the field of dermatological treatments, thus paving the way for exciting prospects in the domain.

Self-Assembling Nanoarchitectonics of Twisted Nanofibers of Fluorescent Amphiphiles as Chemo-Resistive Sensor for Methanol Detection

The inhalation, ingestion, and body absorption of noxious gases lead to severe tissue damage, ophthalmological issues, and neurodegenerative disorders; death may even occur when recognized too late. In particular, methanol gas present in traces can cause blindness, non-reversible organ failure, and even death. Even though ample materials are available for the detection of methanol in other alcoholic analogs at ppm level, their scope is very limited because of the use of either toxic or expensive raw materials or tedious fabrication procedures. In this paper, we report on a simple synthesis of fluorescent amphiphiles achieved using a starting material derived from renewable resources, this material being methyl ricinoleate in good yields. The newly synthesized bio-based amphiphiles were prone to form a gel in a broad range of solvents. The morphology of the gel and the molecular-level interaction involved in the self-assembly process were thoroughly investigated. Rheological studies were carried out to probe the stability, thermal processability, and thixotropic behavior. In order to evaluate the potential application of the self-assembled gel in the field of sensors, we performed sensor measurements. Interestingly, the twisted fibers derived from the molecular assembly could be able to display a stable and selective response towards methanol. We believe that the bottom-up assembled system holds great promise in the environmental, healthcare, medicine, and biological fields.

Organogel of Acai Oil in Cosmetics: Microstructure, Stability, Rheology and Mechanical Properties

Organogel (OG) is a semi-solid material composed of gelling molecules organized in the presence of an appropriate organic solvent, through physical or chemical interactions, in a continuous net. This investigation aimed at preparing and characterizing an organogel from acai oil with hyaluronic acid (HA) structured by 12-hydroxystearic acid (12-HSA), aiming at topical anti-aging application. Organogels containing or not containing HA were analyzed by Fourier-transform Infrared Spectroscopy, polarized light optical microscopy, thermal analysis, texture analysis, rheology, HA quantification and oxidative stability. The organogel containing hyaluronic acid (OG + HA) has a spherulitic texture morphology with a net-like structure and absorption bands that evidenced the presence of HA in the three-dimensional net of organogel. The thermal analysis confirmed the gelation and the insertion of HA, as well as a good thermal stability, which is also confirmed by the study of oxidative stability carried out under different temperature conditions for 90 days. The texture and rheology studies indicated a viscoelastic behavior. HA quantification shows the efficiency of the HA cross-linking process in the three-dimensional net of organogel with 11.22 µg/mL for cross-linked HA. Thus, it is concluded that OG + HA shows potentially promising physicochemical characteristics for the development of a cosmetic system.

Investigating the Synthesis and Characteristics of UV-Cured Bio-Based Epoxy Vegetable Oil-Lignin Composites Mediated by Structure-Directing Agents

Bio-based composites were developed from the epoxy derivatives of Lallemantia iberica oil and kraft lignin (ELALO and EpLnK), using UV radiation as a low energy consumption tool for the oxiranes reaction. To avoid the filler sedimentation or its inhomogeneous distribution in the oil matrix, different structure-directing agents (SDA) were employed: 1,3:2,4-dibenzylidene-D-sorbitol (DBS), 12-hydroxystearic acid (HSA) and sorbitan monostearate (Span 60). The SDA and EpLnK effect upon the ELALO-based formulations, their curing reaction and the performance of the resulting materials were investigated. Fourier-transform Infrared Spectrometry (FTIR) indicates different modes of molecular arrangement through H bonds for the initial ELALO-SDA or ELALO-SDA-EpLnK systems, also confirming the epoxy group's reaction through the cationic mechanism for the final composites. Gel fraction measurements validate the significant conversion of the epoxides for those materials containing SDAs or 1% EpLnK; an increased EpLnK amount (5%), with or without SDA addition, conduced to an inefficient polymerization process, with the UV radiation being partially absorbed by the filler. Thermo-gravimetric and dynamic-mechanical analyses (TGA and DMA) revealed good properties for the ELALO-based materials. By loading 1% EpLnK, the thermal stability was improved to with 10 °C (for Td3%) and the addition of each SDA differently influenced the Tg values but also gave differences in the glassy and rubbery states when the storage moduli were interrogated, depending on their chemical structures. Water affinity and morphological studies were also carried out.

Design and evaluation of molecular organogel based on folic acid as a potential green drug carrier for oral route

OBJECTIVE

The low molecular weight organogels are interesting carriers for pharmaceutical compounds. However, their uses are limited due to the toxicity burden of the organic solvent used. Hence, this study aimed to prepare organogel using folic acid (FA) in different concentrations as a gelator for propylene glycol (PG) biocompatible solvent.

METHODS

The simple mixing method followed by incubation in a water bath at 90 °C was used to prepare organogels. Then, formulations were assessed using different methods including differential scanning calorimetry (DSC), dropping method, attenuated total reflectance - Fourier transform infrared spectroscopy (ATR-FTIR), oscillatory rheology studies, scanning electron microscopy (SEM), and in vitro dissolution study.

RESULTS

Gel formation and its consistency were highly depending on FA concentration. The results showed that increasing the concentration of FA in the organogel led to accelerating the gelation process, and the least amount of FA that could gel the PG was 0.25% w/w. However, higher concentrations were needed to create an organogel with excellent properties. The DSC and dropping studies revealed stable organogels formulations at body temperature. The ATR-FTIR showed interactions between the pteridine ring of FA and PG. The strain amplitude and frequency sweep tests demonstrated an increase in storage modulus values as the concentration of FA increased at 37 °C, which were frequency independent at high frequencies. In addition, the SEM exposed the fabrics like the structure of these organogels. Furthermore, the in vitro dissolution of organogel was pH-dependent, with a high possibility of taking place in the large intestine.

CONCLUSION

FA/PG organogel formulation is a promising carrier for drug and nutraceuticals compound for the oral delivery system.

Nucleoside-Derived Low-Molecular-Weight Gelators as a Synthetic Microenvironment for 3D Cell Culture

For the last few decades, many efforts have been made in developing cell culture methods in order to overcome the biological limitations of the conventional two-dimensional culture. This paradigm shift is driven by a large amount of new hydrogel-based systems for three-dimensional culture, among other systems, since they are known to mimic some living tissue properties. One class of hydrogel precursors has received interest in the field of biomaterials, low-molecular-weight gelators (LMWGs). In comparison to polymer gels, LMWG gels are formed by weak interactions upon an external trigger between the molecular subunits, giving them the ability to reverse the gelation, thus showing potential for many applications of practical interest. This study presents the use of the nucleoside derivative subclass of LMWGs, which are glyco-nucleo-bola-amphiphiles, as a proof of concept of a 3D cell culture scaffold. Physicochemical characterization was performed in order to reach the optimal features to fulfill the requirements of the cell culture microenvironment, in terms of the mechanical properties, architecture, molecular diffusion, porosity, and experimental practicality. The retained conditions were tested by culturing glioblastoma cells for over a month. The cell viability, proliferation, and spatial organization showed during the experiments demonstrate the proof of concept of nucleoside-derived LMWGs as a soft 3D cell culture scaffold. One of the hydrogels tested permits cell proliferation and spheroidal organization over the entire culture time. These systems offer many advantages as they consume very few matters within the optimal range of viscoelasticity for cell culture, and the thermoreversibility of these hydrogels permits their use with few instruments. The LMWG-based scaffold for the 3D cell culture presented in this study unlocked the ability to grow spheroids from patient cells to reach personalized therapies by dramatically reducing the variability of the lattice used.

Structure and Properties of Organogels Prepared from Rapeseed Oil with Stigmasterol

This work used the natural ingredient stigmasterol as an oleogelator to explore the effect of concentration on the properties of organogels. Organogels based on rapeseed oil were investigated using various techniques (oil binding capacity, rheology, polarized light microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy) to better understand their physical and microscopic properties. Results showed that stigmasterol was an efficient and thermoreversible oleogelator, capable of structuring rapeseed oil at a stigmasterol concentration as low as 2% with a gelation temperature of 5 °C. The oil binding capacity values of organogels increased to 99.74% as the concentration of stigmasterol was increased to 6%. The rheological properties revealed that organogels prepared with stigmasterol were a pseudoplastic fluid with non-covalent physical crosslinking, and the G' of the organogels did not change with the frequency of scanning increased, showing the characteristics of strong gel. The microscopic properties and Fourier transform infrared spectroscopy showed that stigmasterol formed rod-like crystals through the self-assembly of intermolecular hydrogen bonds, fixing rapeseed oil in its three-dimensional structure to form organogels. Therefore, stigmasterol can be considered as a good organogelator. It is expected to be widely used in food, medicine, and other biological-related fields.

Study of rapeseed oil gelation induced by commercial monoglycerides using a chemometric approach

Commercial oleogelators rich in monoglycerides (MGs) are complex mixtures of acylglycerides with variable gelling properties, depending on the oil used and their concentration. In this study we developed a chemometric approach to identify the key parameters involved in gelling process. Analytical parameters have been defined, using GC and NMR analysis to identify fatty acids and acylglycerides composing the mixtures. Specific acylglyceride families and compound ratios were calculated to streamline the analytical results. To determine the key analytical parameters, artificial neural networks were used in a QSPR study related to the gelling properties measured by rheology through oscillatory experiments. At low oleogelator concentrations, the MGs especially rich in C16:0 and the ratio of specific isomers both have a positive influence on G'. For high oleogelator concentrations, C18:0-rich acylglycerides and unsaturated/saturated fatty acid ratios have a positive influence on G'. Conversely, at low concentrations, C18:0-rich acylglycerides show a lesser effect on G'.

The effects of oil type and crystallization temperature on the physical properties of vitamin C-loaded oleogels prepared by an emulsion-templated approach

Vitamin C (VC) is widely used as an antioxidant and nutrient to increase the nutritional value and shelf-life of foods. In this article, VC was loaded in oleogels using a simple two-step emulsion-templated approach and the effects of oil type (linseed oil, corn oil, and camellia oil) and crystallization temperature (Tc, -18, 0, 5, and 25 °C) on the physical properties, VC concentration, and oxidation stability of the VC-loaded oleogels were studied. As the amount of saturated fatty acids in the oil phase of the oleogels decreased, the VC loading level, oxidation stability and physical properties of the corn-oil-based oleogel (COG) were better than those of camellia-oil-based oleogels and linseed-oil-based oleogels. At different Tc values, the temperature and frequency dependent storage modulus values for the COG crystallized at 0 °C and 5 °C were not significantly different (P > 0.05), but their values were higher than those for COG crystallized at -18 °C and 25 °C (P < 0.05); the firmness of the COG crystallized at -18 °C and 0 °C was higher than those crystallized at 5 °C and 25 °C (P < 0.05); the network of the COG crystallized at 0 °C was denser than those of the COG crystallized at -18 °C, 5 °C, and 25 °C; and the VC concentration of the oleogels was affected by the crystallization temperature (Tc) and temperature fluctuations. To sum up, a VC-loaded oleogel with excellent mechanical properties was prepared using corn oil and crystallized at 0 °C via an emulsion-templated approach.

Oleogels-Their Applicability and Methods of Characterization

Oleogels or, more precisely, non-triglyceride structured lipid phases have been researched excessively in the last decade. Yet, no comprehensive knowledge base has emerged, allowing technology elevation from the laboratory bench into the industrial food application. That is partly due to insufficient characterization of the structuring systems studied. Examining a single composition decided upon by arbitrary methods does not stimulate progress in the research and technology area. A framework that gives much better guidance to product applications can easily be derived. For example, the incremental structure contribution concept is advocated as a parameter to compare the potency of structuring systems. These can straightforwardly be determined by combining solubility data and structural measurements in the recommended manner. The current method to determine the oil-binding capacity suffers from reproducibility and relevance. A newly developed method is suggested to overcome these shortcomings. The recommended new characterization of oleogels should contribute to a more comprehensive knowledge base necessary for product innovations.

Large amplitude oscillatory shear (LAOS) for nonlinear rheological behavior of heterogeneous emulsion gels made from natural supramolecular gelators

The linear and nonlinear rheological behaviors of heterogeneous emulsions gels made from natural glycyrrhizic acid (GA) nanofibrils and sitosterol-oryzanol mixtures (sterols) were investigated using small amplitude oscillatory shear (SAOS) and large amplitude oscillatory shear (LAOS). The nonlinear rheological response was qualitatively analyzed using normalized Lissajous-Bowditch curves. The microstructure of the emulsion gels strongly depended on the concentration of sterols in the oil phase, and showed a percolated segregated network at 10-20 wt% sterols due to the partial coalescence of droplets, and a jamming transition without coalescence at higher sterols concentration of 30 wt%. The microstructure differences led to different linear and nonlinear viscoelastic behaviors of these emulsion gels. SAOS tests showed that the oil phase structuring by the sterols significantly enhance the viscoelasticity of GA nanofibril emulsion gels, and the percolating emulsion gels exhibited higher elasticity than the jammed emulsion gel, as evidenced by a lower damping factor and frequency power-law exponent. The data of crossover strain, phase angle, and the normalized Lissajous-Bowditch curves from LAOS tests further revealed that compared to the samples in a jammed state or without oil phase structuring, the emulsion gels with a percolating segregated network showed higher structural elasticity and thus were more resistant to large deformations, probably due to the slow relaxation of rigid, hydrodynamically interacting clusters of partially coalesced droplets. These findings could potentially aid in the design of novel emulsion gels, based on all-natural and sustainable building blocks, with specific textural and functional properties for foods, cosmetics, and pharmaceutical applications.

Magnetic particle transport through organogel - an application to DNA extraction

An observation that magnetic particles are transported through organogel encouraged us to investigate its feasibility of liquid-phase displacement in DNA extraction using magnetic particles. Organogel for this study was prepared from a gelator, 12-hydroxystearic acid (12-HSA), and an apolar solvent, methylphenylsilicone oil. The organogel is a gel-like solid material with hydrophobic and elastic properties. These properties, hydrophobicity, and elasticity were demonstrated to be advantageous for liquid compartmentalization and efficient liquid-phase displacement. The extracted DNA with using the organogel device was successfully detected off-chip by conventional real-time PCR.

Engineering water-induced ceramide/lecithin oleogels: understanding the influence of water added upon pre- and post-nucleation

A mixture of ceramide (CER) and lecithin (LEC) at specific ratios was capable of forming oleogels in sunflower oil triggered by adding a trace amount of water. It was noted that the addition of water at different temperatures (TW) resulted in different gelation behaviors and microstructures. To better illuminate the assembly mechanism at different TW, samples with water added at different TW (20 °C, 45 °C, 70 °C and 95 °C) were prepared. The viscoelastic properties, microstructures, and the crystal packing of these samples were investigated. It was observed that all samples prepared at TW of 20 °C and 95 °C formed gels, while most samples prepared at TW of 45 °C and 70 °C were too weak to form gels. Gels prepared at 95 °C were stronger but more fragile in texture compared to gels produced at 20 °C. The crystal morphology of gels drastically changed with TW. Spindle-shaped crystals were observed in gels prepared at low TW (20 °C), while gels prepared at high TW (95 °C) exhibited a network with packed oil droplets stabilized by lamellar shells together with fibrillar crystals in the bulk phase. X-ray diffractograms showed a different reflection peak (d-spacing of 14.5 Å) in gel prepared at 20 °C, compared to the d-spacing in oleogels with a single gelator (13.14 Å and 15.33 Å, respectively, for CER and LEC). Gel prepared at 95 °C showed two long-spacing characteristic peaks, which correspond to the characteristic peaks of CER gel (∼13 Å) and LEC gel (∼12 Å). Fourier transform infrared spectroscopy results indicated that the different gelation behaviors at different TW were mainly caused by vibrational changes in the amide bond of CER. Our hypothesized assembly mechanism can be concluded as: increasing TW resulted in the conversion of CER and LEC crystallization from co-assembly (TW = 20 °C) to self-sorting by individual gelators (TW = 95 °C). In this study, novel water-induced oleogels were produced by manipulating TW, and such information further assists the rational design of lipid-based healthy fat products.

Preparation of Protein Oleogels: Effect on Structure and Functionality

Among available structuring agents that have been used to provide solid properties to liquid oils, protein is a more recent candidate. Due to their nutritional value and high consumer acceptance, proteins are of special interest for the preparation of edible oleogels as an alternative for solid fats. Whereas the field of protein oleogelation is still rather new and just starts unfolding, several preparation methods have been demonstrated to be suitable for protein oleogel preparation. However, there is limited knowledge regarding the link between microstructural properties of the gels and macroscopic rheological properties, and the potential of such protein-based oleogels as a fat replacer in food products. In this review, we therefore provide an overview of various protein oleogel preparation methods and the resulting gel microstructures. Based on the different structures, we discuss how the rheological properties can be modified for the different types of protein oleogels. Finally, we consider the suitability of the different preparation methods regarding potential applications on industrial scale, and provide a short summary of the current state of knowledge regarding the behavior of protein oleogels as a fat replacer in food products.

Structuring of sunflower oil by stearic acid derivatives: Experimental and molecular modelling studies

Structuring of vegetable oils has potential application in food, pharmaceutical and cosmetic products. In this study, structuring effects of stearic acid derivatives on sunflower seed oil were systematically investigated by experimental and molecular simulation methods. Stearic acid (SA), 12-hydroxy stearic acid (HSA) and 2-hydroxyethyl stearate (HES) were able to structure sunflower seed oil, among which the structuring ability of HES was reported for the first time. The oleogel formed with HSA exhibited good mechanical properties (such as hardness, fracturability, adhesiveness, chewiness and storage modulus), which coincided with its highest solid fat content and degree of crystallinity. Oleogels containing SA and HES showed similar mechanical properties. Both the molecular dynamics (MD) simulation and independent gradient model (IGM) confirmed that the HSA dimer possessed the strongest interaction during the self-assembly process while the dimers of HES and SA had similar interactions, which could explain their structuring performance.

Self-assembled toron-like structures in inverse nematic gels

A novel form of nematic gel (N-gel) wherein bright flower-like domains (BFDs) rich in gelator fibres are embedded in a matrix of liquid crystal (LC) molecules has been reported. These gels which we denote as inverse N-gels are unlike typical N-gels in which the LC is encapsulated within an aggregated network of gelator molecules. The self-organization of the helical gelator fibres within the BFDs leads to the creation of localized toron-like structures that are topologically protected due to their skyrmion director profile. Optical and confocal microscopy have been used to deduce the LC director configuration, in order to understand possible intermolecular interactions that can lead to the formation of the twisted structures and the inverse N-gels.

How an organogelator can gelate water: gelation transfer from oil to water induced by a nanoemulsion

A hydrogel can be formed by an organogelator in the presence of a nanoemulsion. It is expected that this is due to a gelation transfer from oil to water. The system started with an oil-in-water nanoemulsion prepared according to a phase inversion temperature (PIT) process. Into this nanoemulsion consisting of Kolliphor® RH40 and Brij® L4 as surfactants, and Miglyol® 812 as oil and water, we introduced the organogelator 12-hydroxyoctadecanoic acid (12-HOA) in the oil phase. After cooling at room temperature, a slow reversible gelation of the water phase occurred with persistence of the nanoemulsion. This thermally reversible system was investigated using various techniques (rheology, turbidimetry, optical and electron microscopies, scattering techniques). Successive stages appeared during the cooling process after the nanoemulsion formation, corresponding to the migration and self-assembly of the organogelator from the oil nanodroplets to the water phase. According to our measurements and the known self-assembly of 12-HOA, a mechanism explaining the formation of the gelled nanoemulsion is proposed.

Hydrogelation with a water-insoluble organogelator - surfactant mediated gelation (SMG)

The low-molecular-weight gelator (LMG) 12-hydroxyoctadecanoic acid (12-HOA) is insoluble in water, but can be solubilized in surfactant micelles. We therefore solubilized 12-HOA at 80 °C in an aqueous solution of cetyltrimethylammonium bromide (CTAB) containing spherical micelles. On cooling this system down to room temperature, a hydrogel is obtained. We will refer to this process as "surfactant-mediated gelation" (SMG). The hydrogels were formed at a lower 12-HOA concentration when sodium salicylate (NaSal) was added to the CTAB system, which induced the formation of wormlike micelles. Hydrogels obtained by SMG from spherical and wormlike micelles are referred to as gelled micellar phases (GMs) and gelled wormlike micellar phases (GWLMs), respectively. Optical microscopy and transmission electron microscopy (TEM) showed that 12-HOA forms self-assembled fibrillar networks (SAFiNs) in both GMs and GWLMs. The sol-gel transition temperature, T_sol-gel, of the GWLM samples was higher than that of the GM samples. Dynamic rheological measurements revealed gel properties (G' > G'' at all angular frequencies) for both gels; however, a higher viscoelasticity was observed for the GWLM samples, which in turn, was reflected in the higher T_sol-gel. Small- and wide-angle X-ray scattering (SWAXS) showed that micelles and gel fibers coexist in the GM and GWLM samples. Our study demonstrates the gelation of aqueous micellar solutions with water-insoluble LMGs.

Potential of Milk Fat to Structure Semisolid Lipidic Systems: A Review

Food production and consumption patterns have changed dramatically in recent decades. The universe of oils and fats, in particular, has been changed due to the negative impacts of trans fatty acids produced industrially through the partial hydrogenation of vegetable oils. Regulations prohibiting its use have led the industry to produce semisolid lipid systems using chemical methods for modification of oils and fats, with limitations from a technological point of view and a lack of knowledge about the metabolization of the modified fats in the body. Milk fat is obtained from the complex biosynthesis in the mammary gland and can be a technological alternative for the modulation of the crystallization processes of semi-solids lipid systems, once it is naturally plastic at the usual processing, storage, and consumption temperatures. The natural plasticity of milk fat is due to its heterogeneous chemical composition, which contains more than 400 different fatty acids that structure approximately 64 million triacylglycerols, with a preferred polymorphic habit in β', besides other physical properties. Therefore, milk fat differs from any lipid raw material found in nature. This review will address the relationship between the chemical behavior and physical properties of semisolid lipids, demonstrating the potential of milk fat as an alternative to the commonly used modification processes.

Counterion Effects on Aggregate Structure of 12-Hydroxystearate Salts in Hexane: A Quantum Mechanical and Molecular Dynamics Simulation Study

Salts of 12-hydroxystearate are important organogelators and grease thickeners, but a structural rationale for their rheological properties remains elusive. We use quantum mechanical calculations and molecular dynamics (MD) simulations to analyze aggregate structures for (1) ( R)-12-hydroxystearic acid (( R)-12HSA), (2) lithium ( R)-12-hydroxystearate (( R)-Li12HS), and (3) sodium ( R)-12-hydroxystearate (( R)-Na12HS). First, quantum mechanical calculations were used to establish the structure and complexation energies of dimers of acetic acid, lithium acetate, and sodium acetate. The expected acetic acid dimer is predicted, and both the lithium acetate and sodium acetate dimer formed a C_{2 h}-symmetric structure. All dimers were sufficiently stable to allow modeling them as pseudocovalent complexes in all-atom, explicit solvent MD. After microsecond-long MD, all systems produced strong ringlike ordered nuclei. The C_{2 h} lithium salt molecules produced aggregates that had the most efficient packing at the head group and a higher frequency of hydroxyl hydrogen bonding compared to the sodium salt. This ordering propensity explains the high melting temperature of ( R)-Li12HS. Also, the higher frequency of hydrogen bonding leads to fewer solvent-exposed hydrogen bond partners. This explains why lithium is a common counterion in high-temperature and water-resistant greases.

Water-induced self-assembly of mixed gelator system (ceramide and lecithin) for edible oil structuring

In the presence of a small amount of water, CER and LEC were self-assembled to form oleogels in sunflower oil. This can be used to produce hard-stock fat replacers as well as for incorporating water-soluble nutrients into oil-based products.

Role of the oil on glyceryl monostearate based oleogels

The high consumption of saturated and trans fats, used in the formulation of lipid-based foods, is associated with incidence of health problems. Organogels or oleogels are a novel class of structured lipids formed from liquid oil as continuous phase entrapped within network of structuring molecules. The aim of this study was to understand the role of oils with different composition on the formation of glyceryl monostearate (GM) gel network. Glyceryl monostearate-based oleogels were produced with the minimal concentration of 5 wt% in sunflower (SF), high oleic sunflower oil (HOS) and coconut oil (CO). The influence of the oil type on the physicochemical properties of the gel was analyzed. The GM gels showed a solid-like behavior using either high oleic sunflower or sunflower oils but did not form a true gel with coconut oil. Although different oils could affect the crystal formation, all gels exhibited needle-like crystal morphology regardless solvent quality. The GM crystals arranged in a lamellar configuration are responsible for entrapping both SF and HOS oils. Degree of saturation of oils might affect GM oleogel properties. Long chain monounsaturated fatty acids favored the packing of GM crystals in a cohesive gel. Furthermore polymorphism with preferential crystalline β' form of GM was formed using a medium containing one and two unsaturation. In conclusion, it was observed that the type of oil influenced the formation of the GM gel network. These findings allow the better understanding of GM-based oleogels, providing opportunity to design for food products with improved technological and nutritional properties.

Periodic Grating-like Patterns Induced by Self-Assembly of Gelator Fibres in Nematic Gels

Periodic orientation patterns occurring in nematic gels, revealed by optical and scanning electron microscopy, are found to be formed by spontaneous self-assembly of fibrous aggregates of a low-molecular-weight organogelator in an aligned thermotropic liquid crystal (LC). Self-organization into periodic structures is also reflected in a calorimetric study, which shows the occurrence of three thermoreversible states, namely, isotropic liquid, nematic and nematic gel. The segregation and self-assembly of the fibrous aggregates leading to pattern formation are attributed to the highly polar LC and to hydrogen bonding between gelator molecules, as shown by X-ray diffraction and vibrational spectroscopy. This study aims to investigate in detail the effect of the chemical nature and alignment of an anisotropic solvent on the morphology of the gelator fibres and the resulting gelation process. The periodic organization of LC-rich and fibre-rich regions can also provide a way to obtain templates for positioning nanoparticle arrays in an LC matrix, which can lead to novel devices.

Thermoresponsive structured emulsions based on the fibrillar self-assembly of natural saponin glycyrrhizic acid

We report the novel use of the naturally occurring saponin, glycyrrhizic acid (GA) as a structuring material to transform liquid oil into a soft-solid structured emulsion system. The GA nanofibrils from the anisotropic self-assembly of GA molecules were first used as stabilizers to fabricate olive oil-in-water emulsions using a facile one-step emulsification at high temperature. Then, the obtained emulsions were further self-organized into the emulsion gel by applying a subsequent cooling to trigger the gel network formation, which is mostly due to the enhanced noncovalent interactions among GA fibrils in the continuous phase as well as at the droplet surface. The GA fibrils could adsorb at the interface in a multilayer form, leading to the formation of unique fibril shells with high electrostatic repulsive force, which could provide superior stability for the GA fibril-stabilized oil droplets and thus the whole emulsion gel during storage and heating. The thermoreversible gel-sol transitions of a self-assembled GA fibrillar network in the continuous phase endow the stable emulsion gels with a temperature-responsive switchable behavior. Moreover, the GA fibril-coated oil droplets embedded in the network were found to be closely packed together and connected with the gel matrix. As a consequence, the emulsion gels exhibited many interesting rheological behaviors, including a high gel strength, shear sensitivity, and good thixotropic recovery. These simple and inexpensive smart responsive oil structuring materials based on natural saponins could find novel applications in the fields of food, pharmaceuticals, or cosmetics.

Potential application of lipid organogels for food industry

Controversial issues regarding the role of trans fatty acids in food have led to progressive changes in the legislation of several countries to include more information for consumers. In response, the industries decided to gradually replace trans fat in various products with the development of fatty bases of equivalent functionality and economic viability to partially hydrogenated fats, causing, however, a substantial increase in the content of saturated fatty acids in foods. Today, the lipid science aims to define alternatives to a problem that is widely discussed by health organizations worldwide: limit the saturated fat content in food available to the population. In this context, organogels have been indicated as a viable alternative to obtain semi-solid fats with reduced content of saturated fatty acids and compatible properties for food application. The objective of this review was to present the studies that address the lipid organogels as an alternative for food application.

Effects of Optical Purity and Finite System Size on Self-Assembly of 12-Hydroxystearic Acid in Hexane: Molecular Dynamics Simulations

12-Hydroxystearic acid (12HSA) and its derivatives are well-known organogelators, and they play critical roles in a variety of applications. The overall aggregate structure of 12HSA is sensitive to the chirality at the 12th carbon, but a fundamental understanding of this dependence is lacking. In this study, molecular dynamics simulations were conducted on microsecond long time scales for (1) (R)-12HSA, (2) (S)-12HSA, and (3) a 50/50 racemic mixture, each solvated at 12.5 wt % in explicit hexane. Self-assembly was accelerated by turning off alkyl chain dihedral gauche states and forcing the molecules to adopt an all-trans conformation. The stability of the resulting aggregates was tested by quenching them with access to gauche states restored. Ordered aggregates produced from optically pure (R)- and (S)-12HSA remained stable for at least 1 μs. The characteristic ordered structure observed is termed a "ring-of-rings" motif, and it contains two twisted six-membered ringlike bundles connected through acetic acid dimerization and surrounded by six satellite bundles. The chirality at the 12th carbon dictates the overall twist of the rings and thereby the handedness of the aggregates. Racemic mixtures did not produce stable ordered aggregates likely due to insufficient enantiomerically pure ring formation. The most prevalent finite-size effect observed was the stochastic formation of percolating aggregates, which were later avoided by using solvent-permeable, solute-impermeable, confining walls. The resulting ordered aggregates were in all important ways identical to those produced in unconfined systems. The combination of cycling off and on gauche states and the semipermeable walls may be an important new way to study the self-assembly underlying aggregation at industrially relevant concentrations of surfactants in organic solvents.

Responsive Emulsion Gels with Tunable Properties Formed by Self-Assembled Nanofibrils of Natural Saponin Glycyrrhizic Acid for Oil Structuring

Saponin nanofibrils assembled from natural glycyrrhizic acid (GA) have been recently shown to be an effective structurant for edible oil structuring. This work showed that the microstructure and mechanical properties of the novel emulsion gels formed by GA fibrils could be well tuned by oil phase polarity. For more polar oils (algal oil), the GA fibrils had a higher affinity to the oil-water interface, showing a faster adsorption kinetics, thus leading to the formation of fine multilayer emulsion droplets with smaller droplet size. Accordingly, the emulsion gels had a denser network microstructure and higher mechanical strength, which should be attributed to the fact that the smaller emulsion droplets could be packed more tightly within the continuous network, providing stronger interdroplet interactions, and thereby contribute to reinforcing the gel matrix. In addition, all emulsion gels had interesting thermoresponsive behavior, independent of oil phase, which is probably due to the thermoreversibility of the hydrogen-bond fibrillar network in the continuous phase.