Phytosterols-induced viscoelasticity of oleogels prepared by using monoglycerides

The synergistic effects of oleogelators based on different structuring mechanisms: A viable way to tailor oleogels with ideal thermo-responsiveness and rheological properties

To explore the potential for creating tunable oleogels, ethylcellulose (EC), monoglycerides (MG), and a combination of β-sitosterol + γ-oryzanol (SO) were utilized to prepare both mono- and multi-component oleogels. Oleogels with desired properties can be produced through the synergistic effects of oleogelators, even while maintaining a constant total mass of gelators at 9 % (w: w). Polarized light microscopy, X-ray diffraction (XRD), and attenuated total reflectance Fourier-transform infrared (ATR-FTIR) spectroscopy analyses revealed that the synergistic effects of the oleogelators arise from a balance between their tendencies for self-assembly and co-assembly, which are driven by non-covalent forces. The multi-component oleogels (OG04, OG06 and OG09) exhibited similar stress-strain responses to those of conventional solid fats (lard or butter). Additionally, their thermal responsiveness during heating and cooling was close to that of conventional solid fats. This work provides a strategy for tailoring novel oleogels, enhancing their applicability across a broader spectrum of food systems.

Development of an Operational Map for the 3D Printing of Phytosterol-Enriched Oleogels: Rheological Insights and Applications in Nutraceutical Design

Three-dimensional (3D) printing attracts significant interest in the food industry for its ability to create complex structures and customize nutritional content. Printing materials, or inks, are specially formulated for food or nutraceuticals. These inks must exhibit proper rheological properties to flow smoothly during printing and form stable final structures. This study evaluates the relationship between rheological properties and printability in phytosterol-enriched monoglyceride (MG) oleogel-based inks, intended for nutraceutical applications. Key rheological factors, including gelation temperature (Tg), elastic (G') and viscous (G″) modulus, and viscosity (µ) behavior with shear rate (γ˙), were analyzed for their impact on flow behavior and post-extrusion stability. Furthermore, this study allowed the development of an operation map to predict successful printing based on material µ and Tg. Oleogels (OGs) were prepared with high-oleic sunflower oil (HOSO) and 10 wt% MG, enriched with phytosterols (PSs) at concentrations between 0 and 40 wt%. While higher PS content generally led to an increase in both Tg and µ, the 10 wt% PS mixture exhibited a different behavior, showing lower Tg and µ compared to the 0 wt% and 5 wt% PS mixtures. The optimal PS concentration was identified as 20 wt%, which exhibited optimal properties for 3D printing, with a Tg of 78.37 °C and µ values ranging from 0.013 to 0.032 Pa.s that yielded excellent flowability and adequate G' (3.07 × 106 Pa) at room temperature for self-supporting capability. These characteristics, visualized on the operational map, suggest that 20% PS OGs meet ideal criteria for successful extrusion and layered deposition in 3D printing.

Hybrid Systems of Oleogels and Probiotic-Loaded Alginate Carriers for Potential Application in Cosmetics

Oleogels (organogels) are systems resembling a solid substance based on the gelation of organic solvents (oil or non-polar liquid) through components of low molecular weight or oil-soluble polymers. Such compounds are organogelators that produce a thermoreversible three-dimensional gel network that captures liquid organic solvents. Oleogels based on natural oils are attracting more attention due to their numerous advantages, such as their unsaturated fatty acid contents, ease of preparation, and safety of use. As a result of the research, two oleogels were developed, into which freeze-dried alginate carriers with a probiotic, L. casei, were incorporated. Two techniques were used to produce probiotic-loaded capsules-extrusion and emulsification. Alginate beads obtained by the extrusion process have a size of approximately 1.2 mm, while much smaller microspheres were obtained using the emulsification technique, ranging in size from 8 to 17 µm. The trehalose was added as a cryoprotectant to improve the survival rate of probiotics in freeze-dried alginate carriers. The encapsulation efficiency for both of the methods applied, the emulsification and the extrusion technique, was high, with levels of 90% and 87%, respectively. The obtained results showed that the production method of probiotic-loaded microspheres influence the bacterial viability. The better strain survival in the developed systems was achieved in the case of microspheres produced by the emulsification (reduction in bacterial cell viability in the range of 1.98-3.97 log in silica oleogel and 2.15-3.81 log in sucragel oleogel after 7 and 30 days of storage) than by the extrusion technique (after a week and a month of oleogel storage, the decrease in cell viability was 2.52-4.52 log in silica oleogel and 2.48-4.44 log in sucragel oleogel).

Structural Build-Up and Stability of Hybrid Monoglyceride-Triglyceride Oleogels

Oleogelation is an alternative oil structuring route to formulate (semi-)solid fats with a reduced amount of saturated fats. Monoglycerides have been identified as effective gelators; however, their application potential can be limited due to challenges regarding mechanical strength and long-term stability. Therefore, the formulation of hybrid fat blends is a promising way to improve the functionality of oleogels. This research focuses on the interaction between mono- and triglycerides (MAGs and TAGs) in hybrid oleogels. A total gelator concentration of 10% (w/w) with changing MAGs-TAGs ratios (increase by 25% on a molar basis; M0-T100, M25-T75, M50-T50, M75-T25, M100-T0) was used. First, the oleogels were produced without shear to unravel the crystallization behavior (DSC, SAXS, WAXS). Next, the oleogels were crystallized with shear to assess the interactions between MAGs and TAGs on macroscale properties (rigidity, oil binding capacity) during storage of 1 day, 1 week, and 4 weeks. A clear distinction could be made between the MAG crystals and TAG crystals in the blends M50-T50 and M75-T25 based on WAXS, SAXS, and phase contrast microscopy. This indicates that both gelators crystallize separately. During the follow-up study of the dynamically produced samples, a synergistic effect was found for Dy-M50-T50 and Dy-M75-T25; however, it was not maintained upon storage. The initial rigidity of 2.4 × 104 Pa and 2.0 × 104 Pa decreased to 1.5 × 104 Pa and 1.0 × 104 Pa for Dy-M50-T50 and Dy-M75-T25, respectively.

Formation, characterization, and application of natural bioactive phytosterol-based oleogels: A review

Oleogels are innovative structured fat systems that can replace detrimental lipids and saturated fats. Among the various gelators used to construct oleogels, phytosterols are regarded as potential oleogelators due to ability to lower blood cholesterol levels and protect patients from cardiovascular illnesses, although little research has been conducted on phytosterols. This article examines the formation, characterization, and application of phytosterol-based oleogels in detail. The oleogelation behaviors of phytosterol-based oleogels are affected by their formulation, which includes phytosterol type, combined oleogelator, proportion, concentration and oil type. These oleogels exhibit potential applications as solid fat substitutes without affecting the texture or sensory properties of food products or as effective delivery vehicles. To encourage the research and implementation of phytosterol-based oleogels, we will ultimately not only highlight problems related to their use in food processing, but also provide a few viewpoints, with the goal of providing fresh insights for advancing trends.

Controlling release of astaxanthin in β-sitosterol oleogel-based emulsions via different self-assembled mechanisms and composition of the oleogelators

In this study, three types of β-sitosterol-based oleogels (β-sitosterol + γ-oryzanol oleogels, β-sitosterol + lecithin, oleogels and β-sitosterol + monostearate oleogels), loaded with astaxanthin, were employed as the oil phase to create oleogel-based emulsions (SO, SL, and SM) using high-pressure homogenization. The microstructure revealed that fine-scale crystals were dispersed within the oil phase of the droplets in the β-sitosterol oleogel-based emulsion. The bioaccessibility of astaxanthin was found to be 58.13 %, 51.24 %, 36.57 %, and 45.72 % for SM, SL, SO, and the control group, respectively. Interestingly, the release of fatty acids was positively correlated with the availability of astaxanthin (P = 0.981). Further analysis of FFAs release and kinetics indicated that the structural strength of the oil-phase in the emulsions influenced the degree and rate of lipolysis. Additionally, the micellar fraction analysis suggested that the nature and composition of the oleogelators in SM and SL also impacted lipolysis and the bioaccessibility of astaxanthin. Furthermore, interfacial binding of lipase and isothermal titration calorimetry (ITC) measurements revealed that the oleogel network within the oil phase of the emulsion acted as a physical barrier, hindering the interaction between lipase and lipid. Overall, β-sitosterol oleogel-based emulsions offer a versatile platform for delivering hydrophobic molecules, enhancing the bioavailability of active compounds, and achieving sustained release.

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.

Towards the development of novel bicomponent phytosterol-based oleogels with natural phenolics

Structuring liquid oils into edible oleogels from natural and abundant plant ingredients has great significance in fields ranging from foods to pharmaceuticals but has proven challenging. Herein, novel bicomponent phytosterol-based oleogels were developed with natural phenolics. Investigating diverse natural phenolics, cinnamic acid (CA) and ethyl ferulate (EF) successfully formed oleogels in combination with phytosterols (PS), where a synergistic effect on the oleogelation and crystallization was observed compared to the corresponding single component formulations. FTIR and UV-vis spectra showed that the gel network was primarily driven by hydrogen bonding and π-π stacking. Furthermore, oscillatory shear demonstrated oleogels featured higher elastic and network structure deformation at molar ratio of 5:5 and 3:7. Moreover, the bicomponent phytosterol-based oleogels displayed partially reversible shear deformation and a reversible solid-liquid transition. Such information was useful for engineering the functional properties of oleogel-based lipidic materials, providing significance for the application in foods, cosmetics and pharmaceuticals industries.

A review of different frying oils and oleogels as alternative frying media for fat-uptake reduction in deep-fat fried foods

Purpose

This review aims to examine the potential of oleogels as a frying medium to decrease oil absorption during deep-frying and enhance the nutritional and energy content of foods. By investigating the factors influencing oil incorporation during deep-frying and examining the application of oleogels in this process, we seek to provide insights into using oleogels as an alternative to traditional cooking oils.

Scope

Deep-frying, a widely used cooking method, leads to the retention of large amounts of oil in fried food, which has been associated with health concerns. To address this issue, researchers have investigated various methods to minimize oil absorption during frying. One promising approach is the use of oleogels, which are thermo-reversible, three-dimensional gel networks formed by entrapment of bulk oil with a low concentration (<10% of weight) of solid lipid materials known as oleogelators. This review will focus on the following aspects: a) an overview of deep-fried foods, b) factors influencing oil uptake and underlying mechanisms for oil absorption during deep-frying, c) the characterization and application of different frying oils and their oleogels in deep-fried foods, d) components of the oleogel system for deep-frying, and e) the health impact, oxidative stability, and sensory acceptability of using oleogels in deep-frying.

Key findings

The review highlights the potential of oleogels as a promising alternative frying medium to reduce fat absorption in deep-fried foods. Considering the factors influencing oil uptake during deep-frying, as well as exploring the properties and applications of different frying oils and their oleogels, can result in improved product qualities and heightened consumer acceptance. Moreover, oleogels offer the advantage of lower fat content in fried products, addressing health concerns associated with traditional deep-frying methods. The capacity to enhance the nutritional and energy profile of foods while preserving sensory qualities and oxidative stability positions oleogels as a promising choice for upcoming food processing applications.

Controlled volatile release from β-sitosterol-based oleogels based on different self-assembly mechanisms

This study examined how the self-assembly mechanisms of β-sitosterol-based oleogels influenced the release of volatile compounds. Microscopy, X-ray diffraction (XRD) and small-angle X-ray scattering (SAXS) measurements showed that the three β-sitosterol-based oleogels (β-sitosterol + γ-oryzanol oleogels (SO), β-sitosterol + lecithin oleogels (SL) and β-sitosterol + monostearate oleogels (SM)) had significant differences in their microstructures, which were formed via different self-assembly mechanisms. SO exhibited the highest oil binding capacity (OBC), complex modulus (G*) and apparent viscosity. Dynamic and static headspace analyses suggested that network structure of β-sitosterol-based oleogels affected the release of volatile components. SO showed the strongest retention effect, followed by SL and SM. The release of volatile compounds mainly related to structural strength and compositions of oleogels. These results indicated that β-sitosterol-based oleogels formed with different self-assembly mechanisms have the potential to serve as effective delivery systems for controlling the release of volatile compounds.

Sucrose Esters as Oleogelators in Mono or Binary Structured Oleogels Using Different Oleogelation Routes

Sucrose esters (SE) have been investigated as structuring agents in oleogels. Due to the low structuration power of SE as single agent, this component has recently been explored in combination with other oleogelators to form multicomponent systems. This study aimed to evaluate binary blends of SEs with different hydrophilic-lipophilic balances (HLBs) with lecithin (LE), monoglycerides (MGs) and hard-fat (HF), according to their physical properties. The following SEs, SP10-HLB2, SP30-HLB6, SP50-HLB11, and SP70-HLB15, were structured using three different routes: "traditional", "ethanol" and "foam-template". All binary blends were made using a 10% oleogelator in 1:1 proportion for binary mixtures; they were then evaluated for their microstructure, melting behavior, mechanical properties, polymorphism and oil-binding capacity. SP10 and SP30 did not form well-structure and self-standing oleogels in any combination. Although SP50 showed some potential blends with HF and MG, their combination with SP70 led to even more well-structured oleogels, with a higher hardness (~0.8 N) and viscoelasticity (160 kPa), and 100% oil-binding capacity. This positive result might be attributed to the reinforcement of the H-bond between the foam and the oil by MG and HF.

Thermal-reversible lacquer wax-based oleofoams in dual stabilization with high ambient stability

In this study, the effect of the content of the lacquer wax and whipping time on the overrun was explored. It was found that an appropriate amount of wax content and whipping time could promote crystal dual stabilization through the Pickering mechanism and the close packing in the bulk phase. Otherwise, it would result in low overrun caused by high viscous and crystal bridging. The addition of polyglycerol polyricinoleate (PGPR) could effectively enhance the overrun by apace absorbing. At the same time, adding PGPR also improved the contact angle, which was beneficial to the adsorption at the A-O interface. The 8 wt% oleogel was partially substituted by high-melting fat palm stearin (POs) and oleofoams were prepared based on blended fat. POs increased the melting point, structural strength, and β'-form crystal of oleofoams, thus improving the storage and temperature stability. The oleofoam has a maximum overrun of 189% and could maintain the shape of the decorating over 15 d at the ambient temperature, showing great potential in low-fat food applications and other delivery systems.

Protective effect of surfactant modified phytosterol oleogels on loaded curcumin

BACKGROUND

Oleogels represent one of the most important carriers for the delivery of lipophilic nutraceuticals. Phytosterols (PS), plant-derived natural sterol compounds, are preferred for oleogel preparation due to their self-assembly properties and health function. However, the relationship between the physical properties of PS-based oleogels and the chemical stability of loaded bioactive compounds is still unclear.

RESULTS

The influence of lecithin (LC) and glycerol monostearate (GMS) on the physical properties of PS-based oleogels made of liquid coconut oil and the stability of curcumin as a model bioactive loaded in the oleogels was investigated. Results showed that the flow consistency index was much higher for GMS-containing oleogels than that for LC-containing oleogels. The optical microscopy and X-ray scattering analysis showed that the addition of GMS in the PS oleogels promoted the formation of a crystal mixture with different crystal polymorph structures, whereas LC addition promoted the formation of needle-like crystals of PS. Using curcumin as a model lipophilic nutraceutical, the GMS-enriched PS oleogels with high crystallinity and flow consistency index exhibited a good retention ratio and scavenging activity of the loaded curcumin when stored at room temperature.

CONCLUSION

This study shows that enhancing the firmness of oleogels made from PS and liquid coconut oil is beneficial to the retention and chemical stability of a loaded bioactive (curcumin). The findings of the study will boost the development of PS-based oleogel formulations for lipophilic nutraceutical delivery. © 2022 Society of Chemical Industry.

Assessment of Natural Waxes as Stabilizers in Peanut Butter

Manufacturers add sugar and fully hydrogenated vegetable oils to peanut butter to avoid its oil separation during storage. Unfortunately, hydrogenated oils are significant sources of saturated fats, and reducing their consumption is challenging for food scientists without affecting the desired characteristics of food products. Therefore, in a preliminary study, 1%, 1.5%, and 2% of three natural waxes (rice bran, carnauba, and beeswax) were added to the natural peanut butter to test their efficacy as a stabilizer. Rice bran and carnauba wax added to peanut butter presented a higher elastic modulus (G’) and lower oil separation percentages than beeswax. However, no significant differences were found between the different percentages of waxes. Thus, in the final experiments, 1% of these selected waxes (rice bran and carnauba waxes) were added directly to the roasted ground peanut. Due to the difficulty of adding high melting point waxes to the peanut butter, a second experiment added wax oleogel (rice-bran and carnauba wax) to defatted peanut flour. After four weeks of storage, all of the samples were examined for their texture (TPA) and oil separation. The sample with directly added bran wax had the highest values for spreadability and firmness, and the lowest oil separation, which was 11.94 ± 0.90 N·s⁻¹, 19.60 ± 0.71 N·s⁻¹, and 0.87 ± 0.05%, respectively. In the peanut flour sample, the spreadability, firmness, and separated oil of the rice bran wax oleogel added sample were 46.95 ± 0.99 N·s⁻¹, 66.61 ± 0.93 N, and 1.57 ± 0.07%, respectively. However, the textural properties of the rice bran wax oleogel added sample were close to the commercial peanut butter (natural and creamy). Therefore, the results indicate that the rice bran wax oleogel could be the potential replacement of the fully hydrogenated oil as a stabilizer.

Edible oleogels stabilized solely by stigmasterol: effect of oil type and gelator concentration

BACKGROUND

Phytosterols are considered to be one of the most promising gelators for obtaining oleogel because of their additional health benefits and natural coexist with vegetable oils. Previous studies have confirmed that individual phytosterols are not capable of structuring vegetable oils unless they act synergistically with other components. However, based on the self-assembly properties of stigmasterol (ST) in organic solvents, we speculate that it can also structure vegetable oils as a gelator alone.

RESULTS

For the first time, the present study confirmed the feasibility of using ST alone as a gelator for structuring of vegetable oils, including rapeseed oil (RSO), olive oil (OLO) and flaxseed oil (FSO). RSO had the lowest ST gelation concentration (4%, w/w), and the oil-binding capacity and firmness value of the oleogels were the highest. The rheological results showed that all the samples were gelatinous (G' > G″). The results of differential scanning calorimeter and X-ray diffraction further confirmed that the properties of RSO-based oleogels are superior to those prepared by OLO and FSO. The microscopic results also confirmed that the crystal structure of RSO oleogels was more uniform, smaller and more densely distributed.

CONCLUSION

The structural properties of the oleogels were positively correlated with the ST concentration, and various analysis indicators showed that the performance of the oleogel based on RSO was better than that of OLO and FSO. In summary, the present study used ST as a gelator to successfully prepare oleogels with excellent properties, which provides a feasible reference for researchers in related fields. © 2022 Society of Chemical Industry.

Synergistic effects of oleogelators in tailoring the properties of oleogels: A review

Conventional solid fats play a crucial role as an ingredient in many processed foods. However, these fats contain a high amount of saturated fats and trans fats. Legislations and dietary recommendations related to these two types of fats set forth as a consequence of evidence showing their deleterious health impact have triggered the attempts to find alternate tailor-made lipids for these solid fats. Oleogels is considered as a novel alternative, which has reduced saturated fat and no trans fat content. In addition to mimicking the distinctive characteristics of solid fats, oleogels can be developed to contain a high amount of polyunsaturated fatty acids and used to deliver bioactives. Although there has been a dramatic rise in the interest in developing oleogels for food applications over the past decade, none of them has been commercially used in foods so far due to the deficiency in their crystal network structure, particularly in monocomponent gels. Very recently, there is a surge in the interest in using of combination of gelators due to the synergistic effects that aid in overcoming the drawbacks in monocomponent gels. However, currently, there is no comprehensive insight into synergism among oleogelators reported in recent studies. Therefore, a comprehensive intuition into the findings reported on synergism is crucial to fill this gap. The objective of this review is to give a comprehensive insight into synergism among gelators based on recent literature. This paper also identifies the future research propositions towards developing oleogels capable of exactly mimicking the properties of conventional solid fats to bridge the gap between laboratory research and the food industry.

Effect of water content on the physical properties and structure of walnut oleogels

This study aimed to investigate the effect of water content on the properties and structure of oleogels by developing walnut oleogel based on potato starch and candelilla wax (CW). Physical, thermal, rheological and microstructure characteristics of the walnut oleogel were determined by texture analyzer, differential scanning calorimeter, rotary rheometer, X-ray diffractometer and optical microscope. Results showed that with increased water content, the hardness of the oleogel increased from 123.35 g to 158 g, whereas the oil loss rate decreased from 24.64% to 10.91%. However, these two values decreased slightly when the ratio of oil to water was 1 : 1. The prepared oleogels have a high elastic modulus, and the flow behavior of all walnut oleogels conformed to that of a non-flowing fluid. Microstructure observation indicated that the crystal size and quantity increased with an increase in water content, and the liquid oil was wrapped in the crystal network by CW and potato starch, forming solidified droplets to further promote gelation. In conclusion, when the ratio of oil to water is 39%, the oleogel has good physical properties and stable crystal structure. These findings can provide an indication of water content in the composition of oleogels.

Production, Characterization, Delivery, and Cholesterol-Lowering Mechanism of Phytosterols: A Review

Phytosterols are natural plant-based bioactive compounds that can lower blood cholesterol levels and help prevent cardiovascular diseases. Consequently, they are being utilized in functional foods, supplements, and pharmaceutical products designed to improve human health. This paper summarizes different approaches to isolate, purify, and characterize phytosterols. It also discusses the hypolipidemic mechanisms of phytosterols and their impact on cholesterol transportation. Phytosterols have a low water-solubility, poor chemical stability, and limited bioavailability, which limits their utilization and efficacy in functional foods. Strategies are therefore being developed to overcome these shortcomings. Colloidal delivery systems, such as emulsions, oleogels, liposomes, and nanoparticles, have been shown to be effective at improving the water-dispersibility, stability, and bioavailability of phytosterols. These delivery systems can be used to incorporate phytosterols into a broader range of cholesterol-lowering functional foods and beverages. We also discuses several issues that need to be addressed before these phytosterol delivery systems can find widespread commercial utilization.

Oleogels prepared with low molecular weight gelators: Texture, rheology and sensory properties, a review

There is a growing need for healthier foods with no trans and reduced saturated fat. However, solid fats play critical roles in texture and sensory attributes of food products, making it challenging to eliminate them in foods. Recently, the concept of oleogelation as a novel oil structuring technique has received numerous attentions owing to their great potential to mimic the properties of solid fats. Understanding textural, rheological and sensory properties of oleogels helps predict the techno-functionalities of oleogels to replace solid fats in food products. This research critically reviews the textural and rheological properties of oleogels prepared by low molecular weight oleogelators (LMWGs) and functional characteristics of foods formulated by these oleogels. The mechanical properties of LMWG-containing oleogels are comprehensively discussed against conventional solid fats. The interactions between the oleogel and its surrounding food matrix are explained, and the sensory attributes of oleogel containing reformulated products are highlighted. Scientific insights into the texture and rheological properties of oleogels manufactured with a wide range of low molecular gelators and their related products are provided in order to boost their implication for creating healthier foods with high consumer acceptability. Future research opportunities on low molecular weight gelators are also discussed.

Ultrasound-assisted gelation of β-carotene enriched oleogels based on candelilla wax-nut oils: Physical properties and in-vitro digestion analysis

•

Candelilla wax mix with peanut, pine nut and walnut oils can form oleogels.

•

Ultrasound increased G’, G’’, firmness and oil-binding capacity of oleogels.

•

Ultrasound treatment improved the protection of β-carotene in oleogels.

•

Ultrasound reduced the amount of β-carotene released during intestinal digestion.

This study investigated the effects of high-intensity ultrasound (HIU, 95 W, 10 s) on the physical properties, stability and in vitro digestion of β-carotene enriched oleogels. Candelilla wax (3 wt%) and nut oils (peanut, pine nut and walnut oil) with or without β-carotene were used to form oleogels. HIU improved the storage modules (G’) of peanut, pine nut and walnut oleogels without β-carotene from 11048.43 ± 728.85 Pa, 38111.67 ± 11663.98 Pa and 21921.13 ± 1011.55 Pa to 13502.40 ± 646.54 Pa, 75322.47 ± 9715.25 Pa and 48480.97 ± 4109.64 Pa, respectively. Moreover, HIU reduced oil loss of peanut, pine nut and walnut oleogels without β-carotene from 23.98 ± 2.58%, 17.14 ± 0.69% and 24.66 ± 1.57% to 17.60 ± 1.10%, 13.84 ± 0.74% and 18.72 ± 3.47%, respectively. X-ray diffraction patterns showed that HIU did not change the form of the crystal (β-polymorphic and β’-polymorphic) but increased the crystal intensity. Polarized light microscope images indicated that all oleogels showed more visible crystals after HIU. After 120 d of storage, HIU decreased the degradation of β-carotene for peanut oil and walnut oil samples (the contents of β-carotene in peanut and walnut oleogels without HIU after 120 d of storage were 897 ± 2 μg/g and 780 ± 1 μg/g, respectively, and those of sonicated samples were 1070 ± 4 μg/g and 932 ± 1 μg/g, respectively). Furthermore, HIU reduced the release of β-carotene in intestinal digestion. In conclusion, HIU could improve the functional properties of wax-nut oils oleogels and their β-carotene enriched oleogels.

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.

Application of Analytical Methods for the Comprehensive Analysis of Oleogels-A Review

Numerous empirical studies have already been conducted on the innovative fat-replacing system defined as oleogel, creating a real urge for setting up a framework for future research, rather than conducting studies with arbitrary methods. This study re-evaluates the utility of some analyses and states some conclusions in order to eliminate the reluctance of food processors and consumers towards the utilization of oleogels as ingredients. The review presents extensively the methods applied for the characterization of various oleogels, while highlighting their addressability or inconveniences. The discussed methods were documented from the research published in the last five years. A classification of the methods is proposed based on their aims or the utility of the results, which either describe the nano-structure and the network formation, the quality of the resulting oleogel or its suitability as food ingredient or other edible purposes. The general conclusions drawn for some classes of oleogels were also revisited, in order to ease the understanding of the oleogel behaviour, to encourage innovative research approaches and to stimulate the progress in the state of art of knowledge.

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.

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.

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.

Fabrication and characterization of stable oleofoam based on medium-long chain diacylglycerol and β-sitosterol

Oleofoams have emerged as attractive low-calorie aeration systems, but saturated lipids or large amount of surfactants are commonly required. Herein, an innovative strategy was proposed to create oleofoams using medium-long chain diacylglycerol (MLCD) and β-sitosterol (St). The oleofoams prepared using MLCD and St in ratios of 15:5 and 12:8 exhibited smaller bubble size and much higher stability. MLCD crystals formed rigid Pickering shell, whereby air bubbles acted as "active fillers" leading to enhanced rigidity. Both Pickering and network stabilization for the MLCD-St oleofoam provided a steric hindrance against coalescence. The gelators interacted via hydrogen bonding, causing a condensing effect in improving the gel elasticity. The oleofoams and foam-based emulsions exhibited a favorable capacity in controlling volatile release where the maximum headspace concentrations and partition coefficients showed a significantly decrease. Overall, the oleofoams have shown great potential for development of low-calorie foods and delivery systems with enhanced textural and nutritional features.

Development and evaluation of a novel oleogel system based on starch-water-wax-oil

A novel oleogel system was developed, and its characteristics and properties were investigated. The results indicate that a low-cost, low-fat and low hardness oleogel product was formed by potato starch, candelilla wax, oil, and distilled water. Specifically, the content of potato starch and candelilla wax in the oleogel system was 5 wt%. A potato starch/candelilla wax ratio from 1.22 to 5.67 led to the formation of a type II starch-lipid oleogel system, and the content of distilled water was 45 times the starch content. All the above-mentioned information demonstrated that starch/wax-based oleogels are a typical lipid system. They can reduce the content of wax and oil in oleogel systems, form oleogel products with low hardness values and exhibit great potential in the field of low-fat food and low-cost food industrial applications.

Effect of Adding Curcumin on the Properties of Linseed Oil Organogels Used as Fat Replacers in Pâtés

Beeswax-based organogels were formulated with linseed oil and curcumin according to a statistical design to increase the oxidative stability of spreadable meat products (pâté) where these organogels (OGCur) were incorporated as fat substitutes. The organogels obtained under optimal conditions (9.12% beeswax, 0.54% curcumin) showed a mechanical strength similar to pork backfat determined by back extrusion and high oil binding capacity (OBC; over 90%). The incorporation of curcumin at this concentration did not lead to any change in the arrangement of the crystal network, OBC, and mechanical, thermal, or rheological properties of the organogels. Beeswax organogels with and without curcumin, with a β’ orthorhombic subcell structure, showed a predominant elastic behavior and a melting event wider and shifted to lower temperatures than pure beeswax, suggesting a plasticizer effect of the oil in the wax crystals. The oxidative stability of the organogels under accelerated oxidation conditions increased due to the incorporation of curcumin. A decrease in the curcumin content was found from day 4 at 60 °C, together with a significantly lower formation of both peroxides and malonaldehyde. When pork backfat was partially or totally replaced by OGCur in pâtés, a noticeable protective effect of curcumin against lipid oxidation was found during chilled storage

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.

Controlling lipid intestinal digestibility using various oil structuring mechanisms

This research demonstrates the ability to direct the rate and extent of lipid hydrolysis of oleogels using a combination of different structuring agents.