Oleogels-Their Applicability and Methods of Characterization

Oleogel classification, physicochemical characterization methods, and typical cases of application in food: a review

The harmful effects of trans and saturated fatty acids have attracted worldwide attention. Edible oleogels, which can structure liquid oils, are promising healthy alternatives to traditional fats. Active research on oleogels is focused on the interaction between unsaturated oils with different fatty acid compositions and low molecular weight or polymer oleogels. The unique network structure inside oleogels has facilitated their application in candies, spreads, meat, and other products. However, the micro- and macro-properties, as well as the functional properties of oleogels vary by preparation method and the system composition. This review discusses the characteristics of oleogels, serving as a reference for the application of oleogels in food products. Specifically, it (i) classifies oleogels and explains the influence of gelling factors on their gelation, (ii) describes the methods for measuring the physicochemical properties of oleogels, and (iii) discusses the current applications of oleogels in food products.

Investigation of the influence of minor components and fatty acid profile of oil on properties of beeswax and stearic acid-based oleogels

Understanding the impact of minor components and the fatty acid profile of oil on oleogel properties is essential for optimizing their characteristics. Considering the scarcity of literature addressing this aspect, this study aimed to explore the correlation between these factors and the properties of beeswax and stearic acid-based oleogels derived from rice bran oil and sesame oil. Minor oil components were modified by stripping the oil, heating the oil with water, and adding β-sitosterol. Oleogels were then prepared using a mixture of beeswax and stearic acid (3:1, w/w) at a concentration of 11.74 % (w/w). The properties of oils and oleogels were evaluated. The findings indicated that minor components and fatty acid composition of the oils substantially influence the oleogel properties. Removing minor components by stripping resulted in smaller and less uniformly distributed crystals and less oil binding capacity compared to the oleogels prepared from untreated oils. A moderate amount of minor components exhibited a significant influence on oleogel properties. The addition of β-sitosterol did not show any influence on oleogel properties except for the oleogel made from untreated oil blend added with β-sitosterol which had more uniform crystals in the microstructure and demonstrated better rheological stability when stored at 5 °C for two months. The oil composition did not show any influence on the thermal and molecular properties of oleogels. Consequently, the oleogel formulation derived from the untreated oil blend enriched with β-sitosterol was identified as the optimal formula for subsequent development. The findings of this study suggest that the physical and mechanical properties as well as the oxidative stability of beeswax and stearic acid-based oleogels are significantly affected by the minor constituents and fatty acid composition of the oil. Moreover, it demonstrates that the properties of oleogels can be tailored by modifying oil composition by blending different oils.

Development and optimization of oleogel made with soy protein isolate and xanthan gum using emulsion template approach and its comparison with solid fats

This study aims to develop oleogel as a potential substitute for solid fats in the diet. A novel combination of unmodified Soy Protein Isolate (SPI) and Xanthan Gum (XG) have been utilized to gelate sunflower oil, using an emulsion template approach. The experimental trials employing Response Surface Methodology are conducted to optimize various parameters that affect the oil binding capacity, textural and rheological properties of the oleogel. The concentration of soy protein varies in the range of 5-15 %, the ratio of soy protein to xanthan gum ranges from 1:2 to 1:4, and the ionic strength varies from 0.2 to 1 M. The goal is to formulate oleogel that closely resembles solid fats. Responses namely the oil binding capacity and gel strength value of oleogel were observed best fitted to a linear model whereas, the hardness of oleogel found following a quadratic model. The SPI-XG combination was found effective in entraping more than 95 % of the oil. The best formulation of SPI: XG, 1:4; SPI concentration, 15 % and ionic strength of 1.0 M with 95.5 % of oil retention and hardness and gel strength value comparable to commercial solid fats.

Natural oleogelators for the formulation of oleogels by considering their rheological and textural perspective; a review

A well-known method for reducing or swapping out undesirable and controversial fats in food is oleogelation. To quantify the effects of droplets-particle inclusion on the textural aspects of gelled systems, a thorough understanding of rheological behavior of oleogels (OGs) is necessary. Otherwise stated, a rational grasp of rheological characterization is essential for food development, optimization, and processing (when touching or putting food into the mouth, rheological flow qualities influence our perception). This narrative review primarily intends to investigate rheological and textural characteristics of various oleogelator-based OGs, such as operative connection between hardness, distortion, stresses, and rheological parameters like viscosity, elasticity, and viscoelasticity, as well as flow behavior and recovery. Expanding oleogelators concentration and synergistic interactions between them increase robustness and moduli values, as compared to single oleogelators. However, given the lack of information on the connection between the OGs' macroscopic rheological characteristics and their microstructural characteristics, this review presents state-of-the-art overview of various oleogelator-based OGs, highlighting the importance of structure-rheology relationships of OGs to provide advanced knowledge on the development of innovative OGs.

Oleogelation based on plant waxes: characterization and food applications

Fats contribute majorly to food flavour, mouthfeel, palatability, texture, and aroma. Though solid fats are used for food formulation due to the processing benefits over oils, their negative health effects should not be overlooked. Oleogelation is thus used to transform liquid oil into a gel which function like fats and provide the nutritional benefits of oils. Additionally, only food-grade gelators convert the oils into solid-like, self-standing, three-dimensional gel networks. Rice bran wax, candelilla wax, carnauba wax, and sunflower wax are mainly used plant waxes for formulating oleogels as a result of their low cost, availability, and excellent gelling ability. A comprehensive information about the wax based oleogels, their characteristics and applications is needed. The present review discusses the effect of different plant-based waxes on the properties of the oleogel formed. The article provides information on how the physical and chemical properties of waxes impact the oleogel properties such as oil binding capacity, critical concentration, rheological, thermal, textural, morphological, and oxidative stability. Moreover, the current and potential applications of oleogels in the food sector have also been covered this article.

Tiger Nut Oil-Based Oil Gel: Preparation, Characterization, and Storage Stability

In this study, Tiger nut (Cyperus esculentus L.) oil-based oleogels were prepared using the emulsion template method with whey protein (WPI; 0.5-2.5% (w/v) and Xanthan gum (XG; 0.1-0.5% (w/v). The microstructure of the oleogels obtained from the high internal phase emulsion (HIPE) and an emulsion after further shearing were observed using an optical microscope and laser confocal microscopy. A series of rheological tests were conducted to evaluate the effect of WPI and XG concentrations on the strength of the emulsion and oleogel. The texture, oil holding capacity, and oxidative stability of oleogels were characterized. The results showed that XG alone could not form oleogel, while the concentration of WPI had more effect than XG. When WPI was at a fixed concentration, the viscoelasticity of HIPE increased with the addition of XG. This was due to the complexation of WPI and XG, forming a stable gel network between the tight emulsion droplets and thus giving it a higher viscoelasticity. With an increase in WPI concentration, the stability and viscoelasticity of the emulsion were increased, and the oil-holding capacity and gel strength of the oleogels were enhanced. Moreover, the addition of XG could significantly enhance the stability and viscoelasticity of the emulsion (p < 0.05), and an increase in the concentration had a positive effect on it. The oleogels showed high gel strength (G' > 15,000 Pa) and good thixotropic recovery when the XG concentration was higher than 0.3% (w/v). WPI (2.0%) and XG (>0.3%) could be used to obtain HIPE with good physicochemical and viscoelastic properties, which in turn lead to oleogels with minimal oil loss, viscoelastic and thixotropic recovery, and temperature stability. Compared with tiger nut oil-based oleogel, tiger nut oil contained more polyunsaturated fatty acids, which were more easily decomposed through oxidation during storage and had lower oxidation stability. This study provides a reference for the preparation of oleogels from food-approved polymers and provides additional theoretical support for their potential application as solid fat substitutes.

Atomic Force Microscopy of Phytosterol Based Edible Oleogels

This work reviews the use of atomic force microscopy (AFM) as a tool to investigate oleogels of edible triglyceride oils. Specific attention is given to those oleogels based on phytosterols and their esters, a class of material the authors have studied extensively. This work consists of a summary of the role of AFM in imaging edible oleogels, including the processing and preparation steps required to obtain high-quality AFM images of them. Finally, there is a comparison between AFM and other techniques that may be used to obtain structural information from oleogel samples. The aim of this review is to provide a useful introduction and summary of the technique for researchers in the fields of gels and food sciences looking to perform AFM measurements on edible oleogels.

Characterization of chitosan-gelatin cryogel templates developed by chemical crosslinking and oxidation resistance of camellia oil cryogel-templated oleogels

In this study, chitosan-gelatin conjugates were prepared by chemical crosslinking of tannic acid. The cryogel templates were developed through freeze-drying and immersed in camellia oil to construct cryogel-templated oleogels. Chemical crosslinking resulted in apparent colour changes and improved emulsion-related/rheological properties on conjugates. The cryogel templates with different formulas exhibited different microstructures with high porosities (over 96 %), and crosslinked samples might have higher hydrogen bonding strength. Tannic acid crosslinking also led to enhanced thermal stabilities and mechanical properties. Cryogel templates could reach a considerable oil absorption capacity of up to 29.26 g/g and prevent oil from leaking effectively. The obtained oleogels with high tannic acid content possessed outstanding antioxidant abilities. After 8 days of rapid oxidation at 40 °C, Oleogels with a high degree of crosslinking owned the lowest POV and TBARS values (39.74 nmol/kg, and 24.40 μg/g, respectively). This study indicates that the involvement of chemical crosslinking would favor the preparation and the application potential of cryogel-templated oleogels, and the tannic acid in the composite biopolymer systems could act as both the crosslinking agent and the antioxidant.

Fabrication and characterization of novel thermoresponsive emulsion gels and oleogels stabilizied by assembling nanofibrous from dual natural triterpenoid saponins

Novel thermoresponsive emulsion gels and oleogels were fabricated by assembling nanofibrous from natural triterpenoid Quillaja saponin (QS) and glycyrrhizic acid (GA). The viscoelasticity of QS-coated emulsion was observed to be remarkably improved by GA and thus obtain the advantages of excellent gelatinous, thermoresponsive and reversible manner due to the viscoelastic texture from GA nanofibrous as scaffolds in continuous phase. In the gelled emulsions, the phase transition of the GA fibrosis network structure upon heating and cooling was attributed to a thermal sensitivity, whereas interface-induced fibrosis assembly of amphiphilic QS endowed the formation of stable emulsion droplets. Then these emulsion gels were further used as an effective template to fabricate soft-solid oleogels with high oil content of 96%. These findings open up new opportunities for the use of all-natural and sustainable ingredients to develop smart soft materials for replace trans and saturated fats in food industry and other fields.

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.

Food-Grade Oleogels: Trends in Analysis, Characterization, and Applicability

Currently, a large number of scientific articles can be found in the research literature in the field focusing on the use of oleogels for food formulation to improve their nutritional properties. The present review focuses on the most representative food-grade oleogels, highlighting current trends in terms of the most suitable methods of analysis and characterization, as well as trends in their application as substitutes for saturated and trans fats in foods. For this purpose, the physicochemical properties, structure, and composition of some oleogelators are primarily discussed, along with the adequacy of oleogel incorporation for use in edible products. Analysis and characterization of oleogels by different methods are important in the formulation of innovative foods, and therefore, this review discusses the most recent published results regarding their microstructure, rheological and textural properties, and oxidative stability. Last but not least, issues related to the sensory properties of oleogel-based foods are discussed, highlighting also the consumer acceptability of some of them.

Oleogels as a Fat Substitute in Food: A Current Review

Fats and oils in food give them flavor and texture while promoting satiety. Despite the recommendation to consume predominantly unsaturated lipid sources, its liquid behavior at room temperature makes many industrial applications impossible. Oleogel is a relatively new technology applied as a total or partial replacement for conventional fats directly related to cardiovascular diseases (CVD) and inflammatory processes. Some of the complications in developing oleogels for the food industry are finding structuring agents Generally Recognized as Safe (GRAS), viable economically, and that do not compromise the oleogel palatability; thus, many studies have shown the different possibilities of applications of oleogel in food products. This review presents applied oleogels in foods and recent proposals to circumvent some disadvantages, as reaching consumer demand for healthier products using an easy-to-use and low-cost material can be intriguing for the food industry.

Oleogels-Innovative Technological Solution for the Nutritional Improvement of Meat Products

Food products contain important quantities of fats, which include saturated and/or unsaturated fatty acids. Because of a proven relationship between saturated fat consumption and the appearance of several diseases, an actual trend is to eliminate them from foodstuffs by finding solutions for integrating other healthier fats with high stability and solid-like structure. Polyunsaturated vegetable oils are healthier for the human diet, but their liquid consistency can lead to a weak texture or oil drain if directly introduced into foods during technological processes. Lately, the use of oleogels that are obtained through the solidification of liquid oils by using edible oleogelators, showed encouraging results as fat replacers in several types of foods. In particular, for meat products, studies regarding successful oleogel integration in burgers, meat batters, pâtés, frankfurters, fermented and bologna sausages have been noted, in order to improve their nutritional profile and make them healthier by substituting for animal fats. The present review aims to summarize the newest trends regarding the use of oleogels in meat products. However, further research on the compatibility between different oil-oleogelator formulations and meat product components is needed, as it is extremely important to obtain appropriate compositions with adequate behavior under the processing conditions.

Edible oleogels based on high molecular weight oleogelators and its prospects in food applications

Food industry is actively looking for alternative ingredients to replace saturated and trans fats in foods while preserving their original organoleptic attributes to ensure consumers' acceptance. A plausible approach is the replacement of solid fats with oleogels. Oleogels can be engineered to mimic properties that are commonly played by regular solid fats but using hydrophobic liquid vegetable oil with an optimum fatty acid profile and, they can also act as carriers for lipophilic bioactive substance. Low molecular weight oleogelators (LMOGs) are well studied and reviewed. In contrast, high molecular weight oleogelators (HMOGs) e.g., polysaccharides and proteins, are not fully researched yet. This review focusses on development of HMOG oleogels produced by means of emulsion templated, direct dispersion, foam templated and solvent exchange methods that can influence the stability, physicochemical properties and their potential application in food industry. Multi-component oleogels can solve the inefficiencies in a single component oleogel and, thus, combinations of HMOGs and HMOGs & LMOGs can produce oleogels with desired properties. These new oleogels can find application as fat substitutes in food products, providing better nutritional and sensory acceptance. A comprehensive overview of recent developments in the field of HMOG and multicomponent oleogels with HMOG is deeply reviewed.

An Attempt to Relate Oleogel Properties to Wax Ester Chemical Structures

Wax esters are considered to have a dominant contribution in the gelling properties of wax-based oleogels. To understand their gelling behavior, oleogels of seven different wax esters (total carbon number from 30 to 46; c = 10% [m/m]) in medium-chain triglycerides oil were characterized. Scanning electron microscopy revealed that wax esters crystallize in rhombic platelets with a thickness of 80 to 115 monomolecular layers. Bright field microscopy showed that the regularity and face length of the crystals increased with the total carbon number and molecular symmetry of the respective wax ester. Oscillatory rheology was used to characterize the gel rigidity (Gmax*). Here, wax ester oleogels with smaller total carbon numbers yielded higher Gmax* values than those of wax esters with higher total carbon numbers. The gel rigidity (Gmax*) inversely correlated with the crystal face length. Smaller and optically less well-defined platelets promoted higher gel rigidities. In the case of the microstructure of a specific oleogel composition being manipulated by a variation in the cooling rates (0.8; 5; 10 K/min), this relationship persisted. The information compiled in this manuscript further elucidates the crystallization behavior of wax esters in oleogels. This contributes to the understanding of the composition–structure–functionality relationship of wax-based oleogels supporting future food applications.

Preparation and Characterization of Novel Oleogels Using Jasmine Floral Wax and Wheat Germ Oil for Oral Delivery of Curcumin

Oleogels (OGs) have gained a lot of interest as a delivery system for a variety of pharmaceuticals. The current study explains the development of jasmine floral wax (JFW) and wheat germ oil (WGO)-based OGs for oral drug (curcumin) delivery application. The OGs were made by dissolving JFW in WGO at 70 °C and cooling it to room temperature (25 °C). The critical gelation concentration of JFW that induces the gelation of WGO was found to be 10% (w/w). The OGs were characterized using various techniques such as Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), microscopic analysis, and mechanical test. XRD data indicated that JFW influences the crystallinity of the OGs. Among the prepared OGs, OG 17.5 showed higher crystallization in the series. Optical microscopic studies demonstrated the formation of fiber structures due to the entanglement of crystals whereas, polarized light micrographs suggested the formation of spherulites or clustered crystallite structures. The mechanical properties of the OGs increased linearly with the increase in the JFW concentration. Curcumin-loaded OGs were examined for their controlled release applications. In summary, the developed OGs were found to have the necessary features for modulating the oral delivery of curcumin.

Wax based oleogels and their application in sponge cakes

The use of high amounts of saturated fatty acids mainly obtained from tropical fats and oils gains increasing rejection from consumers. Use of liquid plant based oils, however, does not deliver necessary functionalities. In this contribution, sunflower-(SFW), bees-wax (BW), ricebran wax (RBW) and a BW-wax mixture (BW : SFWh) were investigated as a potential alternative fat phase in low-density bakery products. Since the food product matrix is composed of complex ingredients, key-functionalities (foam-stabilization, viscoelastic properties, and oil-binding) were first investigated for pure oleogels as oleofoams. It could be demonstrated that all waxes investigated were able to form oleofoams. The location of wax crystal aggregates, at the oil-air interface or in the bulk, was shown to be a significant factor regarding oil-binding and viscoelastic properties. However, it was not possible to transfer all findings made for the oleofoams to the ones made for the oleogel based sponge cakes. There, all oleogels showed improvement compared to the canola oil variant regarding oil-leaping and visual appearance (volume). Sensory evaluation attested satisfactory results for all wax-based oleogel applications. This contribution aims to deliver novel findings for wax-based oleogels as oleofoams as well as an alternative fat phase in low-density bakery products. The gathered results aim to enable a target-oriented characterization of oleogel applications and hence facilitate future use to deliver beneficial products to the market.

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.

Practical scale modification of oleogels by ultrasonic standing waves

Lipid-based materials, such as substitutes for saturated fats (oleogels) structurally modified with ultrasonic standing waves (USW), have been developed by our group. To enable their potential application in food products, pharmaceuticals, and cosmetics, practical and economical production methods are needed. Here, we report scale-up of our procedure of structurally modifying oleogels via the use of USW by a factor of 200 compared to our previous microfluidic chamber. To this end, we compared three different USW chamber prototypes through finite element simulations (FEM) and experimental work. Imaging of the internal structure of USW-treated oleogels was used as feedback for successful development of chambers, i.e., the formation of band-like structures was the guiding factor in chamber development. We then studied the bulk mechanical properties by a uniaxial compression test of the sonicated oleogels obtained with the most promising USW chamber, and sampled local mechanical properties using scanning acoustic microscopy. The results were interpreted using a hyperelastic foam model. The stability of the sonicated oleogels was compared to control samples using automated image analysis oil-release tests. This work enabled the effective mechanical-structural manipulation of oleogels in volumes of 10-100 mL, thus paving the way for USW treatments of large-scale lipid-based materials.

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.

Automated image analysis method for oil-release test of lipid-based materials

We present an automated method to determine oil release from lipid-based materials. Oil-release tests can provide information regarding the ability to retain oil within the structuring network of lipid-based materials. This test provides a first insight into the stability of these materials and their possible applications in food, cosmetic, and pharmaceutical products. The method presented features a simple setup comprising a camera that automatically captures images of the evolution of the oil stain released from lipid-based materials placed on a filter paper. Image postprocessing is performed with two custom-made scripts developed for the freeware application ImageJ. The scripts allow direct calculation of the oil-stain area from all images stored in a folder returning as output numerical values in a table. This method was shown to be:•

inexpensive, as the employed tools and equipment are available in most laboratories both in academia and industry,

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self-running, as the method automatically captures images at predefined time intervals for a certain time span,

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practical, as manual-image analysis is unnecessary (200 images can be automatically analyzed in 3 min).

Improving the nutritional profile of culinary products: oleogel-based bouillon cubes

Structured fat phases are the basis of many consumer relevant properties of fat-containing foods. To realise a nutritional improvement - less saturated, more unsaturated fatty acids - edible oleogels could be remedy. The feasibility of traditional fat phases structured by oleogel in culinary products has been evaluated in this study. In this contribution the oleogel application in bouillon cubes as model system for culinary products is discussed. Three different gelators (sunflower wax (SFW), a mixture of β-Sitosterol and γ-Oryzanol (SO) and ethylcellulose (EC)), at two concentration levels (5% and 10% (w/w)) each, were evaluated with respect to their physical properties, in the food matrix and application. The application of pure and structured canola oil (CO) was benchmarked against the reference, palm fat (PO). The assessment of the prototypes covered attempts to correlate the physicochemical analyses and sensory data. Organoleptic and analytical studies covered storage stability (up to 6 months) monitoring texture, color and fat oxidation. The results indicate that the substitution of palm fat by oleogel is essentially possible. The characteristics of the bouillon cubes are tuneable by gelator choice and inclusion level. Most importantly, the data show that the anticipated risk of intolerable effects of oxidation during shelf life is limited if antioxidants are used.

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.