Formation of oleogels based on edible lipid materials

Effect of Biodegradable Hydrophilic and Hydrophobic Emulsifiers on the Oleogels Containing Sunflower Wax and Sunflower Oil

The use of an appropriate oleogelator in the structuring of vegetable oil is a crucial point of consideration. Sunflower wax (SFW) is used as an oleogelator and displays an excellent potential to bind vegetable oils. The current study aimed to look for the effects of hydrophobic (SPAN-80) and hydrophilic (TWEEN-80) emulsifiers on the oleogels prepared using SFW and sunflower oil (SO). The biodegradability and all formulations showed globular crystals on their surface that varied in size and number. Wax ester, being the most abundant component of SFW, was found to produce fibrous and needle-like entanglements capable of binding more than 99% of SO. The formulations containing 3 mg of liquid emulsifiers in 20 g of oleogels showed better mechanical properties such as spreadability and lower firmness than the other tested concentrations. Although the FTIR spectra of all the formulations were similar, which indicated not much variation in the molecular interactions, XRD diffractograms confirmed the presence of β' form of fat crystals. Further, the mentioned formulations also showed larger average crystallite sizes, which was supported by slow gelation kinetics. A characteristic melting point (Tm~60 °C) of triglyceride was visualized through DSC thermograms. However, a higher melting point in the case of few formulations suggests the possibility of even a stable β polymorph. The formed oleogels indicated the significant contribution of diffusion for curcumin release. Altogether, the use of SFW and SO oleogels with modified properties using biodegradable emulsifiers can be beneficial in replacing saturated fats and fat-derived products.

Oleogel-based emulsions: Concepts, structuring agents, and applications in food

This review discusses the application of oleogel technology in emulsified systems. In these systems of mimetic fats, water-in-oil or oil-in-water emulsions can be obtained, but, here, we cover emulsions with an oil continuous phase in detail. Depending on the percentage of water added to the oleogels, systems with different textures and rheological properties can be developed. These properties are affected by the characteristics and concentration of the added components and emulsion preparation methods. In addition, some gelators exhibit interfacial properties, resulting in more stable emulsions than those of conventional emulsions. Oleogel-based emulsion are differentiated by continuous and dispersed phases and the structuring/emulsification components. Crucially, these emulsions could be applied by the food industry for preparing, for example, meat products and margarines, as well as by the cosmetics industry. We present the different processes of emulsion elaboration, the main gelators used, the influence of the water content on the structuring of water-in-oleogel emulsions, and the structuring mechanisms (Pickering, network, and combined Pickering and network stabilization). Finally, we highlight the applications of these systems as alternatives for reducing processed food lipid content and saturated fat levels.

Polymeric Gels and Their Application in the Treatment of Psoriasis Vulgaris: A Review

Psoriasis is a chronic skin disease, and it is especially characterized by the occurrence of red, itchy, and scaly eruptions on the skin. The quality of life of patients with psoriasis is decreased because this disease remains incurable, despite the rapid progress of therapeutic methods and the introduction of many innovative antipsoriatic drugs. Moreover, many patients with psoriasis are dissatisfied with their current treatment methods and the form with which the drug is applied. The patients complain about skin irritation, clothing stains, unpleasant smell, or excessive viscosity of the preparation. The causes of these issues should be linked with little effectiveness of the therapy caused by low permeation of the drug into the skin, as well as patients’ disobeying doctors’ recommendations, e.g., concerning regular application of the preparation. Both of these factors are closely related to the physicochemical form of the preparation and its rheological and mechanical properties. To improve the quality of patients’ lives, it is important to gain knowledge about the specific form of the drug and its effect on the safety and efficacy of a therapy as well as the patients’ comfort during application. Therefore, we present a literature review and a detailed analysis of the composition, rheological properties, and mechanical properties of polymeric gels as an alternative to viscous and greasy ointments. We discuss the following polymeric gels: hydrogels, oleogels, emulgels, and bigels. In our opinion, they have many characteristics (i.e., safety, effectiveness, desired durability, acceptance by patients), which can contribute to the development of an effective and, at the same time comfortable, method of local treatment of psoriasis for patients.

Recent advances on food-grade oleogels: Fabrication, application and research trends

In order to improve the nutritional and quality characteristics of food, solid fats are widely used in food formulations. With the continuous improvement of consumers' awareness of health in recent years, substantial attempts have been carried out to find substitutes for solid fats to reduce saturated fatty acid content in foods. Oleogels have drawn increasing attention due to their attractive advantages such as easy fabrication, superior fatty acid composition and safe use in food products to satisfy consumers' demands for healthy products. This review provides the latest information on the diversified oleogel systems. The feasibility of oleogel and oleogel-based system as nutraceutical vehicles is elucidated. The type as well as concentration of oleogelators and the synergistic effect between two or more oleogelators are important factors affecting the properties of obtained oleogel. Oleogels used in nutraceutical delivery have been shown to offer increased loading amount, enhanced bioaccessibility and targeted or controlled release. These nutrients wrapped in oleogels may in turn affect the formation and properties of oleogels. Furthermore, the future perspectives of oleogels are discussed. The feasible research trends of food-grade oleogel include oleogel-based solid lipid particle, essential oil-in-oleogel system, delivery of probiotics, nutraceuticals co-delivery and microencapsulated oleogel.

Study of monoglycerides enriched with unsaturated fatty acids at sn-2 position as oleogelators for oleogel preparation

The effect of using highly unsaturated 2-monoglycerides as oleogelators on the properties of soybean oil oleogels designed to eliminate saturated and trans fatty acids was investigated in this study. We adopted a novel two-step synthesis aiming to increase the yield of the 2-monoglycerides. The optimal synthesis conditions were a substrate weight ratio of 2:1 (w/w), 10% Lipozyme 435 (w/w total reactants), and 4 h of reaction time at room temperature. Under these conditions, the 2-monoglyceride yield (40.69%) increased by 10% compared to that of the conventional synthesis route. Additionally, soybean oil oleogels prepared using 10% 2-monoglycerides with or without rice bran wax were systematically characterized by polarized light microscopy, a texture analyzer, XRD spectroscopy, and rheometry. Comparative studies indicated that a combination of rice bran wax and 2-monoglycerides had synergistic effects on gel properties. A mixture of 4% rice bran wax and 6% 2-monoglycerides was found to provide better oleogels.

Formation, structural characteristics and physicochemical properties of beeswax oleogels prepared with tea polyphenol loaded gelators

In this study, a tea polyphenol (TP) loaded beeswax gelator (TP gelator) was constructed and incorporated into soybean oil to improve the oxidative stability of oleogels. The effects of TP on the structure and storage stability of oleogels were investigated. The TP gelator prepared by embedding TP into beeswax improved the dispersity of TP in lipids. The thermal characteristics and X-ray diffraction analysis showed that the components of the TP gelator coexisted homogeneously and TP was well dispersed in beeswax. The Fourier-transform infrared spectra indicated that the phenolic hydroxyl group of TP had intermolecular force with the quaternary ammonium nitrogen in the choline portion of soybean lecithin. The formation of needle-like crystals by beeswax restricted the flow of liquid oil, and TP did not participate in the construction of the internal network structure of the oleogel. In the accelerated storage experiment at 60 °C, the peroxide value of the TP loaded oleogel decreased by 60.6% at the end of the storage period compared with soybean oil. TP was successfully embedded in the oleogel without changing its structure, which not only solved the problem of poor dispersion of TP in oil, but also showed a significant inhibitory effect on lipid oxidation.

Beeswax: A potential self-emulsifying agent for the construction of thermal-sensitive food W/O emulsion

Fabrication of food-grade water-in-oil (W/O) emulsions without surfactant, as the primary substitutes of trans-fat and saturated fat, was still a significant challenge in food science. A facial method has been adopted to fabricate W/O emulsions at 20 °C. The obtained emulsion had long-time stability, and there was no apparent phase separation or oiling-out after 60 days of storage. In this system, beeswax served as a stabilizer for both oleogels and oleogel-based emulsions. The sol-gel melting temperature of the oleogel was 37 ± 0.5 °C by regulating beeswax content to 4% w/w, and then the oleogel was used to fabricate W/O emulsion with the droplet diameter of around 9 μm. Thermo-reversible and thixotropic properties of oleogels were both retained for emulsions. Furthermore, both oleogels and oleogel-based emulsions had compact gel-like structures. The self-emulsifying W/O emulsions without surfactant would have great potential applications in food industry, pharmaceutical industry and feed industry.

Effect of high-intensity ultrasound on the oleogelation and physical properties of high melting point monoglycerides and triglycerides oleogels

Oleogels and oleogelation routes have been extensively studied in the past decade; however, the industry has not yet implemented this technique due to price, availability, and clean label. The objective of this study was to evaluate the synergism of binary oleogels structured by monoglycerides (MG) and high melting point triacylglycerols (HF) with and without high-intensity ultrasound (HIU) according to their physical properties. MG:HF (0:6, 1:5, 2:4, 3:3, 4:2, 5:1, and 6:0) oleogels were produced by mixing at 70 °C with a stirring of 350 rpm for 5 min, followed by a cooling and storage at 20 °C for 24 hr. A 20-kHz HIU was applied for 10s, 30s, or 10s using three pulses (10sON/10sOFF) during the cooling step via a macro tip (12.7 mm) and 50% amplitude (56 W) in the presence of few -crystals. Samples were evaluated according to their hardness, oil-binding capacity (OBC), microstructure, melting behavior, viscoelasticity, and flow behavior. The best physical properties were found in the MG6:HF0 oleogel, with a hardness of 1.2 N, elasticity of 5.5 kPa, viscosity of 99 Pa⋅s and 99% OBC. These properties were reduced with the decrease of MG in the blend. The sonication did not improve the MG6:HF0, instead it affected its properties negatively. However, sonication showed a positive effect on the blends of MG and HF. The hardness was improved at least threefold and OBC around 20%, these effects were already observed using only 10s sonication. Sonocrystallization induced secondary nucleation and changed the crystalline material only in blends containing HF indicating the better effect of the sonocrystallization on oleogels in the presence of high-melting points triacylglycerols. PRACTICAL APPLICATION: Oleogels are a valuable alternative in food industry to replace trans and reduce saturated fatty acids content in many food products. The combination of a binary structuration and use of high-intensity ultrasound that is a physical green technology will give the food industry information on how to improve the physical properties of oleogels without increasing the amount of oleogelators, giving a future alternative to clean label and sensory claims of oleogels applications.

The Effect of Cooling Rate on the Microstructure and Macroscopic Properties of Rice Bran Wax Oleogels

The main purpose of this paper is to study the microstructure and macroscopic characteristics of rice bran wax (RBW) oleogels at a cooling rate of 1°C/min and 10°C/min by polarized light microscopy, X-ray diffraction, differential scanning calorimetry, texture analyzer, and micro rheometer. The oleogels of soybean oil were prepared by RBW in concentrations of 5%, 7.5%, 10%, 15% and 20% (wt/wt). The results of this study indicated that the concentration of RBW and cooling rates were affected by the crystal size and spatial distribution of these crystals. For the same RBW concentration, oleogels contained smaller crystals when cooled at 10°C/min compared to 1°C/min. And the oleogels obtained at a rate of 10°C/min exhibited a tighter crystal network, lower melting point, harder texture, and energy storage modulus. These results demonstrated the impact of cooling rate on the rheological behavior, nucleation, and crystallization process.

Glyceryl monostearate-based oleogels as a new fat substitute in meat emulsion

Bologna sausages were produced with 25, 50, 75 and 100% of their pork fat content replaced by monoglyceride based-oleogels prepared from conventional or high oleic sunflower oils. Physicochemical, technological, and sensory properties of Bologna sausages were evaluated. Emulsion stability was little affected by fat replacement. All treatments batters exhibited characteristic rheological properties of gels (G' > G″). Overall, the addition of oleogel as a fat substitute made the sausages lighter and a small increase in hardness was observed in the sausages with total fat replacement by oleogels. The sliceability was affected by the reformulation and a higher number of slices were obtained in samples with oleogels in relation to the control. These results were associated to the product structure that became more compact as the amount of pork fat was reduced. However, all samples showed good acceptance by the consumers and no significant difference was observed between treatments. The results showed that monostearate-based oleogel can be a potential fat replacer with higher amount of unsaturated fatty acids to be used in meat products, but retaining the desired characteristics of the traditional products.

Crystallization, microstructure and polymorphic properties of soybean oil organogels in a hybrid structuring system

Organogels are semi-solid systems where the liquid phase is immobilized for three-dimensional network self-sustained formed by structuring agents capable to hold a larger quantity of liquid oil. The use of these structuring agents or crystallization modifiers, as specific triacylglycerols, emulsifiers and high molecular weight - high melting point lipids, have been recognized as the main alternative for obtaining low saturated fats for food formulation. The aim of this work was to evaluate the crystallization, microstructure and polymorphism properties of hybrid soybean oil (SO) organogels, formulated with 6% (w:w) of structuring agents through a centroid simplex system added singly, in binary or ternary association of candelilla wax (CW), sorbitan monostearate (SMS) and fully hydrogenated palm oil (FHPO). The thermal behavior, crystallization kinetics, physical stability by temperature cyclization, microstructure and polymorphism were evaluated. FHPO and CW increased the stability and ability to form crystalline networks in organogels, while SMS accelerated the crystallization process. The structuring agents increased the initial and final crystallization temperatures, even as the melting temperatures and the enthalpy values of organogels. Time-temperature cyclization (cyclization 1: 5 °C/48 h + 35 °C/24 h + 5 °C/24 h; cyclization 2: 35 °C/48 h + 5 °C/72 h) showed that all the systems resulted in firm and stable organogels, except when SMS or FHPO were used singly. CW promoted formation of denser crystalline networks with higher solids content, quick crystallization onset and higher melting points that indicates adequate thermal resistance; while FHPO increased the solid content although it was effective to obtain organogels only at the cooling temperature (5 °C). The binary interaction of FHPO + CW increased the thermal resistance of organogels; and the interactions among SMS + CW and SMS + CW + FHPO although it was effective to obtain organogels. Regardless of the presence and proportions of structuring agents, organogels were characterized by beta polymorphism.

Quantifications of Oleocolloid Matrices Made of Whey Protein and Oleogels

Consumer demand for high protein content and plant-based fat has necessitated novel approaches to healthy food products. In response to this need, oleogels (OG) (structured liquid oils) emerged as a possible means of not only replacing saturated and trans fats but also delivering food protein. Nevertheless, an in-depth view of the structure of networks made of OG and protein is deficient. Hence, the objective of this study is developing oleocolloid (OC) (whey protein and rice bran wax OG) and hydro-oleocolloid (HOC) (OC + water) matrices with varying protein content (2.5–7.5%) to characterize their structural properties. Thermal analysis of the matrices via differential scanning calorimetry (DSC) documented the effects of hydrophobic interactions on the protein structure and its stability. Whey protein denaturation temperature increased from 74.9 °C to 102.8 °C in the presence of high oleic soybean oil. The effects of vegetable oil on WPI structure was also verified by FTIR spectroscopy. Data analysis revealed slight structural changes of the WPI secondary structure in the hydrophobic oil medium and the α-helix and β-sheet proportion in the emulsion medium was significantly altered. Similar analysis was performed in OC and HOC networks to quantify possible interactions between protein and rice bran wax. Results indicated that the protein was denatured during the thermal and mechanical conditions required for the oleogelation process, while it did not affect the systems’ solid fat content (SFC) and polymorphic patterns of the oleogels. However, DSC analysis showed different onset of melting for OC and HOC samples due to colloidal interactions between the protein and the lipid phase. The role of these chemistry was confirmed by microscopy analyses where OC and HOC matrices displayed notably different microstructural properties. The observed differences in the structural properties between OC and HOC matrices indicate the different colloidal interactions mediated by oleogelation process and the liquid medium type (oil vs. emulsion).

Preparation and characterization of oleogel emulsions: A comparative study between the use of recovered and commercial sunflower waxes as structuring agent

The objective of this study was to evaluate the capacity of recovered sunflower waxes (RW) to be used as a structuring agent of oleogel emulsions in comparison with commercial sunflower waxes (CW). RW were recovered from filter cake with a simple hexane extraction procedure. For this purpose, oleogel-based emulsions were prepared using 2%, 3.5%, and 5% w/w wax in oleogel and characterized using several physicochemical techniques in order to evaluate the potential of these materials to develop products with functionality similar to commercial margarines. The total wax esters content of RW was similar to that of the CW and was mainly composed of wax esters with more than 44 carbon atoms (crystallizable waxes). Polarized light and scanning electron microscopy showed that RW produced emulsions with more intricate crystalline networks composed of smaller platelets than CW. The melting enthalpy was greater in CW emulsions than RW emulsions, which was in agreement with the thermal behavior found for CW and RW. The oil binding capacity of CW oleogel emulsions was higher than the RW ones, and this property improved with the increase in wax concentration. Likewise, the elastic behavior, as well as hardness and adhesiveness, increased with the wax content as a result of a greater amount of microstructural elements composing the network of these semisolid materials. The oleogel emulsions stability was monitored for 2 months at room temperature. The increase of CW concentration slowed down the coalescence process, but this behavior was not observed for RW emulsions. Obtained results demonstrated that RW oleogel emulsions have the potential to replace the functionality of soft spreadable products. PRACTICAL APPLICATION: Wax esters are organogelators that have been shown to successfully gel liquid oil at low concentrations. In this work, we are interested in evaluating the potential of sunflower waxes recovered from filter cake, a waste generated during refined oil production, to structure oil and produce oil-in-water emulsions with functionality similar to commercial margarines. With this, it is sought not only the development of healthier fats but also the use of wastes to generate more sustainable products.

The role of hydrogen bonds in TAG derivative-based oleogel structure and properties

Glycerol monosterate (GMS) and stearic acid (SA) share a similar carbon chain structure while SA has a carboxyl head group and GMS has two free hydroxyl groups. The current research focuses on the relationship between GMS and SA chemical structure, nano and mesoscale crystal structure, and the oleogel macroscopic characteristics. Molecular analysis revealed the formation of different types of hydrogen bonds, which disappear upon temperature increase at different temperatures. Nano-structural analysis exhibited tight and ordered lamellar structures for SA compared with loosely packed short lamellar structures in GMS oleogel, presumably due to its larger hydrophilic head group. Microstructure imaging revealed ordered anisotropically orientated needle-like crystals in SA and isotopically ordered braid-like crystals in GMS oleogels. Mechanical analysis revealed that gel strength is enhanced when crystal structure is isotropically oriented, similar behavior seen is composite materials, where the structuring agent crystals behave like a reinforcing agent within the oil matrix.

Stabilization of peanut butter by rice bran wax

To improve stability of peanut butter, rice bran wax (RBX) was added into peanut butter as a stabilizer by formation of organogel. Effects of addition of RBX, heating temperature, and cooling temperature on stabilization effect of peanut butter by RBX were investigated. The optimum conditions were as follow: addition of RBX at 4.0 wt%; heating temperature at 85 °C, and cooling temperature at 20 °C. Under the optimum conditions, the oil loss of peanut butter decreased from 12.19% to 4.04%, and the adhesiveness of peanut butter increased from 23.5 to 165.9 g·s. After storage for 25 weeks, the acid value (AV) of peanut butter prepared under the optimum conditions increased from 0.65  to 0.80 mg/g, and the peroxide value (PV) increased from 0.116 to 0.127 meq/kg. However, the AV of natural peanut butter increased to 1.73 mg/g, and PV increased to 0.178 meq/kg. The confocal laser scanning microscope images showed that the cooling temperature significantly affected crystallization of RBX and distribution of solid particles. When RBX formed needle-like crystals and peanut solid particles were evenly distributed in the oil phase, stable peanut butter was obtained. These results suggested that the RBX was an effective stabilizer for peanut butter. PRACTICAL APPLICATION: Oil separation often occurred to peanut butter during storage, which reduced the sensory quality of peanut butter and shortened its shelf life. This study stabilized peanut butter by addition of RBX based on the formation of organogel, which was of great practical significance to improve the shelf life of peanut butter.

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.

Development and In vitro Evaluation of Nifedipine Gel Formulations for Anorectal Applications

Objective:

Current study focuses on the formulation and characterization of lipophilic and hydrophilic gel formulations of nifedipine to treat anal fissure via anodermal application.

Methods:

Lipophilic gels were prepared with Aerosil grades as gelling agents in bulk oils. Polyethylene glycols, hydroxypropyl methylcellulose, and Carbopol® 974P were used as gelling agents in water and propylene glycol for forming hydrophilic gels. The effect of repeated Freeze-Thaw Cycles (FT-C) on microstructures of the gels was investigated by examining viscosity, rheology and textural properties. Aerosil 200 containing lipophilic gels exhibited thixotropic behavior with plastic flow properties and higher viscosities.

Result:

Accordingly, their compressibility and adhesiveness increased. FT-C caused notable changes in microstructures and textural properties of the lipophilic gels excluding the formulation containing Aerosil 200-in-isopropyl myristate. Among the hydrophilic gels, the viscosity of Carbopol® 974P gels increased depending on the amount of polymer, triethanolamine and water; these gels featured plastic flow without thixotropic behavior. Their compressibility and adhesiveness were higher than other gel formulations with stable post-FT-C characteristics. The higher flux values of nifedipine were observed from water containing Carbopol® 974P gel.

Conclusion:

The results of the stability tests showed that the Carbopol® 974P gel had a longer shelf life than the Aerosil 200-in-isopropyl myristate gel.

Physical properties and cookie-making performance of oleogels prepared with crude and refined soybean oil: a comparative study

The objective of this research was to fabricate crude soybean oil oleogels (CSO) using β-sitosterol (BS) and/or monoacylglycerol (MAG) and compare their role with that of refined soybean oil oleogels (RSO) in cookie making. Both crude and refined soybean oil oleogels were formed with BS or MAG, or the combination of both (1 : 1) at a fixed concentration of 10 wt%. The thermal behavior of the oleogels was measured using differential scanning calorimetry (DSC). The crystal structure and morphology of the oleogels were characterized using X-ray diffraction (XRD) and polarized light microscopy (PLM). The hardness of the oleogel and commercial vegetable shortening was compared using a texture analyzer. The characteristics of cookies made with the oleogels were compared with those of cookies made with commercial vegetable shortening. Overall, the incorporation of BS and/or MAG into crude and refined soybean oil can produce oleogels with solid-like properties. Refined soybean oil formed stronger and firmer oleogels as compared to crude soybean oil. RSO structured by BS presented branched fiber-like, elongated plate-like, and needle-like crystals while the same oil gelled by MAG contained spherulite crystals. RSO made with the combination of BS and MAG displayed crystal morphologies from both BS and MAG. The same crystal morphologies were observed in CSO with lower quantities. Comparing the quality of cookies made with the oleogels and commercial vegetable shortening, equal or better performance of both RSO and CSO in terms of weight, thickness, width, spread ratio, and hardness of cookies than that of commercial vegetable shortening was observed. By combining the results of the physical characterization and cookie making performance, it can be concluded that both crude and refined soybean oleogels could resemble commercial shortening, which offers the possibility of using oleogels to replace shortening in the baking industry.

Effect of Toluene and Hexane Sorption on the Rheology and Interfacial Properties of Lecithin-Based Emulsion Gels

A novel sorbent material consisting of a gel made from canola oil and water, emulsified with lecithin, was used to remove two model solvents from water. Sorption capacity was quantified through small-scale batch experiments. The structure and the mechanical properties of the gel were compared with and without added solvent to assess their cohesiveness upon removing contaminants from water. Confocal microscopy showed that the initial gel consisted of water droplets clustered in a canola oil continuous phase. The G' of the gels increased with solvent absorption to a maximum at 33% (v/v) hexane or 24% (v/v) toluene. Larger absorbed volumes led to decreases in G' of the gel. G' for solvent mixtures of 50% toluene and 50% hexane was intermediate between G' measured for the same volumes of pure solvents. Confocal microscopy suggests that the decrease of G' upon addition of large solvent volumes was due to a simple dilution effect. It is hypothesized that the initial increase in storage modulus was caused by changes in the structure of the lecithin films formed at the oil-water interfaces. This hypothesis was evaluated through measurements of interfacial tension, visualization of the interface with optical microscopy, force measurements of a single droplet under compression using a cantilevered-capillary force apparatus, compressional isotherm measurements conducted using a Langmuir trough. The cantilevered-capillary force apparatus and Langmuir trough experiments demonstrated that lecithin films at the canola oil-water interface were rigidified by toluene and hexane addition.

Synthesis, physicochemical properties, and health aspects of structured lipids: A review

Structured lipids (SLs) refer to a new type of functional lipids obtained by chemically, enzymatically, or genetically modifying the composition and/or distribution of fatty acids in the glycerol backbone. Due to the unique physicochemical characteristics and health benefits of SLs (for example, calorie reduction, immune function improvement, and reduction in serum triacylglycerols), there is increasing interest in the research and application of novel SLs in the food industry. The chemical structures and molecular architectures of SLs define mainly their physicochemical properties and nutritional values, which are also affected by the processing conditions. In this regard, this holistic review provides coverage of the latest developments and applications of SLs in terms of synthesis strategies, physicochemical properties, health aspects, and potential food applications. Enzymatic synthesis of SLs particularly with immobilized lipases is presented with a short introduction to the genetic engineering approach. Some physical features such as solid fat content, crystallization and melting behavior, rheology and interfacial properties, as well as oxidative stability are discussed as influenced by chemical structures and processing conditions. Health-related considerations of SLs including their metabolic characteristics, biopolymer-based lipid digestion modulation, and oleogelation of liquid oils are also explored. Finally, potential food applications of SLs are shortly introduced. Major challenges and future trends in the industrial production of SLs, physicochemical properties, and digestion behavior of SLs in complex food systems, as well as further exploration of SL-based oleogels and their food application are also discussed.

Evaluation of linseed oil oleogels to partially replace pork backfat in fermented sausages

BACKGROUND

Nowadays, fat replacement in meat products is a matter of concern in the meat industry. The objective of this study was to evaluate the replacement of pork backfat with two oleogels of linseed in dry-cured sausages.

RESULTS

Five batches of dry-cured sausages were prepared with two oleogels, a mixture of γ-oryzanol and β-sitosterol (SO) and beeswax (B), at two levels of replacement (20% and 40%) (SO-20, SO-40, B-20, and B-40, respectively) and a control batch. The fatty acid profile improved in terms of nutrition: the polyunsaturated fatty acid / saturated fatty acid (PUFA/SFA) and n-6/n-3 ratio was about 1.41 and 0.93 for the higher levels of replacement, SO-40 and B-40, respectively. Quality parameters such as pH and color also changed with the inclusion of oleogels, resulting in changes in the sensory quality.

CONCLUSION

Oleogels based on linseed enabled the replacement of pork backfat in fermented sausages. Depending on the level of fat substitution, such oleogels could replace fat in dry-cured sausages at the industrial level. © 2019 Society of Chemical Industry.

Utilization of unsaponifiable matter from rice bran oil fatty acid distillate for preparing an antioxidant-rich oleogel and evaluation of its properties

Rice bran oil fatty acid distillate (RBOFAD) is an important by-product obtained from the physical refining process. This fatty acid distillate contains high a amount of Unsaponifiable Matter (γ-oryzanol 3.27 gm/100gm UM; total tocopherol 10.93 mg/100 g UM; total phytosterol 21.81 g/100g UM; squalene 1.15 g/100 g UM and total fatty alcohol 73.34 g/100 g UM) and free fatty acids. Antioxidant-rich Oleogels were obtained from rice bran wax (RBW), rice bran oil fatty acid distillate (RBOFAD) and refined rice bran oil. The main objective of this study was to utilize the antioxidant-rich unsaponifiable matter of RBOFAD (UMRBOFAD) as an organogelator along with rice bran wax, which also acts as a good organogelator. Antioxidant-rich oleogel was prepared using UMRBFAD, ethylcellulose (EC) and RBW at 2%, 2%, 3% on weight basis, respectively, in refined rice bran oil and this antioxidant-rich oleogel was compared with rice bran oil oleogel using RBW at 7% on weight basis of rice bran oil. These oleogels were evaluated using a combination of techniques such as differential scanning calorimetry (DSC), polarized light microscopy (PLM), Viscosity, synchrotron radiation X-ray diffraction (SR-XRD) and FTIR Spectroscopy. The differential scanning calorimetry (DSC) measured the thermal properties of rice bran oil oleogel and high antioxidant-rich oleogel. Polarized light microscopy images revealed needle-like crystals for RBW. SR-XRD measurements were used for clarification of the crystal structures of the building blocks of these oleogels. The antioxidant activities of oleogels were evaluated involving DPPH and ABTS assays.

Oleogels in Food: A Review of Current and Potential Applications

Legislative limitations of the use of trans and saturated fatty acids, the rising concerns among consumers about the negative effects of some fats on human health, and environmental and health considerations regarding the increased use of palm fat in food and biodiesel production drove to innovations in reformulating fat-containing food products. Oleogelation is one of the most in-trend methods for reducing or replacing the unhealthy and controversial fats in food products. Different edible oleogels are being formulated by various techniques and used in spreads, bakeries, confectioneries, and dairy and meat products. This review exclusively focuses on up-to-date applications of oleogels in food and mechanisms of gelation, and discusses the properties of new products. Research has produced acceptable reformulated food products with similar technological and rheological properties as the reference products or even products with improved techno-functionality; however, there is still a high need to improve oleogelation methods, as well as the technological process of oleogel-based foods products. Despite other strategies that aim to reduce or replace the occurrence of trans and saturated fats in food, oleogelation presents a great potential for industrial application in the future due to nutritional and environmental considerations.

Effect of high-oleic rapeseed oil oleogels on the quality of short-dough biscuits and fat migration

Short-dough biscuits are popular snacks. Unfortunately, fat used in most of these products has low nutritional value due to the high content of saturated fatty acids. The most popular fat used in bakery products is palm oil. In this work high-oleic rapeseed oil was used in the form of oleogels structured by waxes (canelilla, rice bran, yellow and white beeswax), monoacyloglicerols and ethylcelullose. In this form oil keeps nutritional value and has solid consistency. Obtained oleogels were significantly different than palm oil in terms of texture and viscosity. However, using oleogel with 5% of monoacylglicerols, as a shortening let to obtain biscuits with similar properties to control sample (with palm oil). Addition of 2 and 3% of candelilla wax, 8% of ethylcelullose, 2% of rice bran wax and 5% of monoacylglicerols allowed to get products from which lipid fraction migration was similar or smaller then from control sample.

Effect of the ratio between behenyl alcohol and behenic acid on the oleogel properties

HYPOTHESIS

In oleogel food systems (based on the mixture between stearic acid and stearyl alcohol) the strong effect of the weight ratio (R) between these two components on the textural and structural properties is well described. The effect of R for other fatty acids and fatty alcohols is less explored. Moreover, they do not show an enhancement of the oleogel properties for specific R. The effect of R on the oleogel properties, for a mixture of fatty acid and fatty alcohol with longer alkyl chains (behenyl alcohol and behenic acid) in sunflower and soybean oils, which are raw materials widely used in cosmetic and pharmaceutical industries, was investigated.

EXPERIMENTS

We characterized the oleogel properties as a function of R in terms of structuring potential: hardness, oil loss and gel stability. This information was correlated with microstructural data obtained at different length scales by coupling optical microscopy, DSC, SFC, SAXS and WAXS experiments.

FINDINGS

Our results highlight that R tunes the oleogel properties in a comparable manner to previous results obtained for stearic acid and stearyl alcohol-based oleogels. Two specific R (8:2 and 7:3) close to the 3:1 molecular ratio gave oleogels with both the highest hardness and stability. The morphology and size of the mixed crystals obtained for these R cannot solely explain why they are stronger gels with low oil loss in comparison to the other R. The almost complete crystallization for these two R is one of the key parameters controlling the oleogel properties. As described in the literature, we also suggest that the differences in oleogel properties come from the spatial distribution of the crystalline mass. In this study, we confirm that the effect of the 3:1 molecular ratio in mixed surfactant systems described more than 50 years ago for foams, emulsions and Langmuir monolayers occurs also on the crystallization of mixed fatty alcohol and fatty acid in oils leading to better oleogels properties.

Physicochemical and rheological properties of soybean organogels: Interactions between different structuring agents

High consumption of trans and saturated fats has been related to the development of cardiovascular diseases, justifying the application of organogels as possible substitutes for industrial fats. The aim of this study was to evaluate the physicochemical and rheological characteristics of soybean organogels that were prepared with 6% (w:w) of structuring components by a simplex centroid design, individually added, in binary and ternary associations with candelilla wax (CW), sorbitan monostearate (SMS) and fully hydrogenated palm oil (HPO). The formulated organogels were evaluated for hardness, solid content, and rheological behavior. The organogels containing a high proportion of HPO had higher solid content: 8.1% with the addition of isolated HPO and a solid content of 6.9% with the addition of HPO + CW. However, isolated use of HPO resulted in lower compression/extrusion strength (0.85 N) than that obtained with isolated CW (10.45 N). All organogels exhibited Hershel-Bulkley rheological behavior, except organogel 2 (containing only SMS), which showed pseudoplastic behavior. Thus, the structuring agents used to form the organogels are capable of changing the physical behavior of unsaturated lipids depending on whether a combination of CW + HPO was added, a ternary interaction with a higher proportion of CW, and the use of isolated CW as a structuring agent, resulting in organogels of greater stability and hardness.

Effects of wax concentration and carbon chain length on the structural modification of fat crystals

Natural waxes are cost-effective and potential fat crystallization modifiers; however, there is limited information about their implementation in solid triacylglycerol (TAG) oil. Herein, we investigated the effects of two natural waxes, namely, candelilla wax (CLW) and rice bran wax (RW), with different concentrations (2, 4, 6, and 8 wt%) and carbon chains on the crystal growth and structure of palm kernel stearin (PKS85). CLW significantly accelerated the PKS85 crystallization process. Both waxes could induce a new hydrocarbon chain with the lengths of 3.70 and 4.15 Å during the TAG crystallization, respectively. Particularly, X-ray diffraction (XRD) indicated that PKS85 combined with CLW showed a similar lamellar thickness (d₀₀₁) and crystal domain size (ξ) with pure PKS85, whereas that of PKS85 containing RW was 1.7-1.8 and 1.5-1.8 fold higher, respectively. This result corresponded to the carbon chain length of CLW and RW, which was double and quadruple that of PKS85, respectively. Further, these variations were reflected in the crystal microstructures of PKS85 with CLW and RW, where the former showed small homogeneous crystals, while the latter displayed large rod-like layered crystals. In addition, the firmness significantly increased when CLW and RW were added, which is possibly attributed to the fact that the waxes became the backbone of the crystal "fence". Our findings give clear insight into the interaction between TAGs and wax molecules in the crystallization process, which can help guide the utilization of natural waxes in the modification of fats.

Effects of cooling temperature profiles on the monoglycerides oleogel properties: A rheo-microscopy study

The oleogelation process has become in a great interest area for the food sector. The aim of this study was to understand the effect of cooling temperature profiles (CTP) applied during oleogelation on microstructure and some macroscopic properties of monoglycerides (MG) oleogels. To this purpose, oleogels from MG and high oleic sunflower oil were produced using programed CTP corresponding to the actual temperature evolution of the samples when they are left at rest to progress in a specific ambient temperature (AT). In order to evaluate the crystal formation during the gelation process, a torsional rheometer equipped with a rheo-microscope (RM) module was used. This allowed us to carry out simultaneously rheological measurements and record images of the gels during their formation process. Overall, microstructural characteristics were determined: fractions of crystalline material and oil, crystal length and shape, the Avrami index, and the fractal dimension. Although crystal formation took place during a similar range of temperatures (~55-46 °C), significant morphological differences in the distribution and size of crystal and aggregates were observed depending on the applied CTP, and the area occupied by the crystals and oil phase did not depend on CTP used. RM images were useful to follow the kinetics of crystallization as well as to identify a more restricted time domain in the rheological behavior allowing to find more accurate Avrami index values. Furthermore, the analysis of RM images turned out to be an efficient approach to obtain accurate measurements of the fractal dimension. High fractal dimension values were associated with gels exhibiting high number of homogeneous small crystals. Oleogels composed by this network generated a material with high capacity to retain oil. A weak-link regime approach applied to the dynamic systems was appropriate to describe the relationship between the elastic modulus and the crystal formation during the oleogels structuration. In conclusion, these findings may serve to the food industry to achieve a better understanding of the oleogelation process that allows it to control the quality of obtained oleogels, which could be utilized to replace and/or reduce the trans and saturated fats in food formulations.