Preparation of Protein Oleogels: Effect on Structure and Functionality

Oleogels based on protein fibrils-hordein-xanthan gum complexes: Formation, structure, and physicochemical properties

Recently, oleogelators derived from natural biopolymers have received greater interest. In this study, whey protein isolate fibril (WPIF), ovalbumin fibril (OVAF), soybean protein isolate fibril (SPIF) and pea protein isolate fibril (PPIF) were used as structural agents and separately combined with hordein and xanthan gum (XG), to fabricate oleogels via emulsion template method. The TEM results of the complexes illustrated the crosslinked fibril networks were formed with hordein as the corresponding junctions, where XG coated on the fibril-hordein complex surface in nanoparticles. Hydrogen bonds and hydrophobic interactions were the main driving forces in the formation of fibrils-hordein binary complexes, and XG adhered to the binary complexes via electrostatic attraction. Fibrils affect the formation of oleogels by different interfacial behaviors of emulsions. The CLSM results revealed that oleogel based on OVAF had the densest network, followed by WPIF-, PPIF- and SPIF-based oleogels. Furthermore, the sequence of oil binding capacity, storage/loss modulus, viscosity, and hardness of the oleogels exhibited similar trends with that of the network density. In comparison with soybean oil, the release rates of the free fatty acids in the oleogel systems were notably reduced. This study provided new insights for developing protein fibrils-based oleogels.

Microstructure and rheology of cellulose bead-filled whey protein isolate oleogels

This study investigated the oleogelation of cellulose bead dispersions in a sunflower oil oleogel made with solvent-transferred whey protein isolate. The microstructure and rheology of the mixed gels depended on the ratio of hydrated cellulose beads to proteins (9:1, 8:2, 7:3, and 1:1). Two gel stabilization mechanisms were identified. In gels dominated by cellulose beads, capillary bridging and the avoidance of the continuous oil phase dominated network formation. With increasing protein content, the cellulose beads became covered by a layer of aggregated protein, leading to a protein-dominated network. All mixed gels displayed similar elastic behaviour. Oil release was greater in the gels at the highest cellulose bead to protein ratio, which aligned with the presence of void spaces in the network visible under the microscope. These findings serve as the foundation to explore other particle-filled oleogels for use in food-related applications.

From liquid to solid: Exploring techniques, applications, and challenges of structured oils as fat replacements in food formulations

Oil structuring is a strategy used to change the physical state of liquid oils to mimic the behavior of solid fats. In the past years, following the legislative bans on using partially hydrogenated fats and recommendations on limiting saturated fatty acid intake, oil structuring has become a fast-developing research area. This review explores the current state of applications developed for oil structuring, considering the challenges and prospects. Processes such as direct and indirect oleogelation, as well as interesterification (acidolysis, alcoholysis, glycerolysis, and transesterification), are described, outlining the main factors governing them. The review also presents the potential applications and enhancement of the functional properties of structured oils in various food formulations. From the latest literature, the industrial applicability of structured oils is discussed. This work provides a well-structured overview of the broad and diverse topic of fat mimetics and oil structuring, creating a solid base for a better understanding of the topic and spotting the challenges associated with their application.

Characteristics and Functional Properties of Bioactive Oleogels: A Current Review

Oleogels have been a revolutionary innovation in food science in terms of their health benefits and unique structural properties. They provide a healthier alternative to traditional solid or animal fats. They have improved oxidative stability and nutritional value to maintain the desirable sensory qualities of lipid-based foods. Moreover, oleogels offer an ideal carrier for poorly water-soluble bioactive compounds. The three-dimensional structure of oleogels can protect and deliver bioactive compounds in functional food products. Bioactive compounds also affect the crystalline behavior of oleogelators, the physical properties of oleogels, and storage stability. Generally, different incorporation techniques are applied to entrap bioactive compounds in the oleogel matrix depending on their characteristics. These approaches enhance the bioavailability, controlled release, stability of bioactive compounds, and the shelf life of oleogels. The multifunctionality of oleogels extends their applications beyond fat replacements, e.g., food preservation, nutraceutical delivery, and even novel innovations like 3D food printing. Despite their potential, challenges such as large-scale production, cost efficiency, and consumer acceptance remain areas for further exploration. This review emphasizes the understanding of the relationship between the structure of oleogels and their functional properties to optimize their design in different food applications. It also highlights the latest advancements in bioactive oleogels, focusing on how they incorporate bioactive compounds such as polyphenols, essential oils, and flavonoids into oleogels. The impact of these compounds on the gelation process, storage stability, and overall functionality of oleogels is also critically examined.

Metamaterial-based injection molding for the cost-effective production of whole cuts

The escalating global demand for meat products has intensified ecological concerns, underscoring the need for sustainable meat alternatives. Although current methods effectively imitate ground meat, mimicking whole cuts, which constitute 54% of the global market, remains challenging due to the lack of scalable technology. Injection molding is a massively scalable manufacturing technology developed for the polymer industry. Here, we introduce two injectable metamaterials: a thermally irreversible fat composite we named proteoleogel, and a multi-scaled meat analog produced by low-temperature extrusion. Viscoelastic screening of plant proteins identifies mung bean for its ability to stabilize complex oleogel structures, mimicking the mechanics of adipose tissue. Mechanical analysis reveals that low-temperature extrusion produces microscale isotropic fibers and mesoscale anisotropic structures mimicking muscle and fascia. These metamaterials can be injection-molded into various whole cuts, from chops to T-bones. Blinded taste tests indicate a 43% preference for our plant-based steak analog. Moreover, technical economic analysis shows injection molding is more cost-effective than 3D printing, costing $9/kg compared to $38/kg. This research represents a step in sustainable food production, offering cost-effective and scalable solutions for the entire meat market.

Preparation of protein-based aerogels and regulation and application of their absorption properties: a review

Challenges still persist in the preparation of healthy foods through the structuring of liquid oils, and the encapsulation and delivery of functional components. However, protein-based aerogels (PAs) with unique nutritional and health properties as well as various kinds of tunable absorption properties hold promise for solving these problems. In this review, the methods and characteristics of aerogels prepared from various animal and plant proteins were reviewed. In addition, considering the satisfactory structure of amyloid and its outstanding gelation and absorption properties, we proposed accelerating the development of amyloid aerogels in the future. Then, the relationship between their microstructure (specific surface area, pore characteristics, and stability) and absorption properties was discussed. The methods of regulating the absorption properties of PA by hydrogel preparation process, drying technology and surface coating were also emphasized. Finally, we summarized the research advances in PAs for liquid oil structuring and functional ingredient delivery, and provided an outlook for PAs development. The selection of suitable proteins and effective regulation of absorption properties are crucial considerations for improving the applicability of PAs. This review serves as a theoretical reference for the development of healthy, multifunctional and practicable PAs and their products.

Changing the horizon of food frying from the use of liquid oil to semi-solid gel

Deep fat frying is the most adopted process of producing fried food products; it involves mass and heat transfer to form fried products with good colour, crispiness, flavour, taste, and texture. However, frequent consumption of these products is a concern due to higher oil content that poses threats to human health. Hence, there is a need to find an alternative frying medium for deep fat frying of food products to obtain fried products having lower fat content. The structuring of liquid oil to convert it into semi-solid gel by the process of oleogelation forms oleogel. The use of oleogel as a frying medium gives fried products with good oxidative, textural, and sensory attributes. The Oleogelator used in the formulation of oleogel plays a significant role in maintaining the stability of oleogel. An increase in the oleo gelator concentration decreases the oil uptake in the fried product. The superior product quality and high consumer acceptance of oleogel fried products indicate that oleogel is a potential frying medium. The scope of the present review is to cover the heat and mass transfer perspective of the deep fat frying process, factors responsible for oil uptake in fried products, formulation and components of semi-solid system, discussion on various characteristics of semi-solid system as frying medium, comparative assessment of oil uptake in food fried in oleogel and conventional oil and finally covering specific examples showing the efficacy of liquid oil oleogel as a frying medium.

Development and characterization of wax-bovine bone protein-grapeseed oil composite oleogels: Experimental and molecular simulation studies

Three new types of composite oleogel formulations were designed. Specifically, oleogels were prepared using 90% grapeseed oil as the oil phase and carnauba wax (CW)/beeswax/rice bran wax-bovine bone protein (BBP) as gelators. All samples were solid and had an oil-binding capacity of >90%. BBP addition considerably improved the waxy texture of the oleogel and had an important effect on the crystalline network. X-ray diffractometry indicated that BBP increased the β'-crystal content. All samples showed sol-gel thermodynamic behavior under temperature scanning. Fourier-transform infrared spectroscopy and molecular docking confirmed the formation of noncovalent interactions dominated by van der Waals forces during the development of the oleogel. The optimal components of the three oleogels exhibited an excellent effect of slowing down the release of free fatty acids. This study could serve as a reference for the development and application of wax-protein as a new binary gelator in the food industry.

Development and characterization of tilapia skin collagen-inulin oleogel as the potential fat substitute in beef patty formulations

The effects of inulin addition, olive oil content, and ultrasonic treatment on the rheological, texture, and structural properties of collagen-based oleogels were investigated in this study. Furthermore, the fat substitution ability of the oleogel in low-fat beef patties was evaluated. Initially, a uniform and dense network cross-linked structure was found when the ratio of collagen to inulin complex was 1:5. The oleogel sample exhibited good stability and oil binding ability with an additional amount of 50 % olive oil. Ultrasonic treatment improved the stability of the oleogel structure in all samples. Additionally, the addition of inulin reduced cooking loss in beef patties. Beef patties prepared at a 50 % fat substitution level showed physical properties that were the least different from those of pure adipose tissue (control group), which could significantly reduce the content of saturated fatty acids and improve the storage stability of beef patties. This study provided guidance for the application of collagen-inulin oleogel in food processing.

Preparation of Ovalbumin/Xanthan Gum/Chitosan Pickering Emulsion Oleogel Added with Amomum villosum Lour. Extract and Its Application in Cookies

In this study, a new oleogel system was constructed and used as a fat substitute in the processing of cookies. The preparation process of Amomum villosum Lour. extract (AVE) was optimized based on antioxidant activity and yield firstly. Then, the AVE, ovalbumin, chitosan, and xanthan gum were used as raw materials to prepare a composite Pickering emulsion oleogel. The results showed that when the concentration of AVE, chitosan, and XG were 0.1%, 2.5%, and 0.3%, respectively, a stable and uniformly distributed Pickering emulsion oleogel was formed. In this case, the particle size of the composite oleogel was relatively small; the absolute value of zeta potential was higher; the microstructure was more stable, with less aggregation and flocculation; and the thermal stability and freeze-thaw stability were excellent. In addition, the addition of AVE enhanced the gel properties of the oleogel and had good solid-like properties, and strengthened the binding force, as well as the oxidation stability, making the whole system more stable. In addition, the results of the application of the composite oleogel in the cookies showed that the AVE-ovalbumin/xanthan gum/chitosan Pickering emulsion oleogel had similar sensory and texture properties to the butter group. The addition of AVE can delay the crispness, cohesiveness, hardness, and the rate of malondialdehyde formation in cookies during storage. In conclusion, the AVE-ovalbumin/xanthan gum/chitosan Pickering emulsion oleogel had good physicochemical stability and showed great potential in replacing saturated fat (butter) in baking products (cookies).

A review of oleogels applications in dairy foods

The characteristics of dairy products, such as texture, color, flavor, and nutritional profile, are significantly influenced by the presence of milk fat. However, saturated fatty acids account for 65% of total milk fat. With increased health awareness and regulatory recommendations, consumer preferences have evolved toward low/no saturated fat food products. Reducing the saturated fat content of dairy products to meet market demands is an urgent yet challenging task, as it may compromise product quality and increase production costs. In this regard, oleogels have emerged as a viable milk fat replacement in dairy foods. This review focuses on recent advances in oleogel systems and explores their potential for incorporation into dairy products as a milk fat substitute. Overall, it can be concluded that oleogel can be a potential alternative to replace milk fat fully or partially in the product matrix to improve nutritional profile by mimicking similar rheological and textural product characteristics as milk fat. Furthermore, the impact of consuming oleogel-based dairy foods on digestibility and gut health is also discussed. A thorough comprehension of the application of oleogels in dairy products will provide an opportunity for the dairy sector to develop applications that will appeal to the changing consumer needs.

A Review of Whey Protein-Based Bioactive Delivery Systems: Design, Fabrication, and Application

The efficacy of many edible bioactive agents is limited by their low water dispersibility and chemical instability in foods, as well as by their poor bioaccessibility, low absorption, and metabolism within the human gastrointestinal tract. Whey proteins are amphiphilic molecules that can be used to construct a variety of edible carrier systems that can improve the performance of bioactive ingredients. These carrier systems are being used by the food and biomedical industries to encapsulate, protect, and deliver a variety of bioactive agents. In this article, we begin by providing an overview of the molecular and functional characteristics of whey proteins, and then discuss their interactions with various kinds of bioactive agents. The ability of whey proteins to be used as building blocks to assemble different kinds of carrier systems is then discussed, including nanoparticles, hydrogels, oleogels, bigels, nanofibers, nanotubes, and nanoemulsions. Moreover, applications of these carrier systems are highlighted. Different kinds of whey protein-based carriers can be used to encapsulate, protect, and deliver bioactive agents. Each kind of carrier has its own characteristics, which make them suitable for different application needs in foods and other products. Previous studies suggest that whey protein-based carriers are particularly suitable for protecting chemically labile bioactive agents and for prolonging their release profiles. In the future, it is likely that the applications of whey protein-based carriers in the food and pharmaceutical fields will expand.

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

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

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.

Edible oleogels for oral delivery of berberine in dairy food: In-vitro digestion study

Oleogel is a viscoelastic, spreadable and semi-solid structure, which is used as a fat substitute and a controller the release of bioactive compounds. The aim of this study was to develop low fat dairy dessert enriched with berberine with applying oleogel system as delivery system and fat replacer. The oleogel prepared with an emulsion-templated methods based on soluble interaction of whey protein concentrate (WPC), WPC-basil seed gum (BSG), and WPC-xanthan gum (XG). In the first step, berberine release kinetic in in-vitro gastrointestinal environment was studied. The results showed that the mouth environment had the highest release rate of berberine. Cooperation of hydrocolloids in oleogel increase stability of structure in stomach condition in compared with WPC oleogel. The suitable model to fit the oleogels contain beberine was the Korsmeyer-Papas that was the highest R 2 (.98). According to release results of berberine from oleogel network, the oleogel 0.6BSG:WPC was chosen and applied in formulation of dairy dessert at different levels (0%, 25%, 50%, 75% and 100% of oleogel) instead of cream. The dessert contained uncoated berberine had the unacceptable bitterness in comparison with samples containing coated berberine with oleogel. The overall acceptance decreased with increment of oleogel due to increasing of bitter taste. Appling berberine (therapeutic compound) and oleogel (fat-substitute) to achieve marketable consumer products showed positive effects on trend of the study, especially at low level of substitution.

Alginate Cryogels as a Template for the Preparation of Edible Oleogels

A high consumption of solid fats is linked to increased inflammation and a risk of cardiovascular diseases. Hence, in recent years, there has been increasing interest in the development of oleogels as a fat substitute in food products. Oleogels are edible gels that contain a large amount of liquid oils entrapped in a 3D network and that can potentially be applied to spreads, bakery goods, meat, and dairy products in order to lower their saturated fat content while maintaining a desirable food texture and mouthfeel. In this work, alginate cryogels were studied as templates for three different edible oils in the process of oleogel formation. Two different freezing regimes to obtain cryogels were employed in order to evaluate better the textural and morphological capabilities of cryogels to adsorb and retain edible oils. It was shown that rapid freezing in liquid nitrogen produces alginate cryogels with a lower density, higher porosity, and a greater ability to adsorb the tested oils. The highest uptake and holding oil capacity was achieved for olive oil, which reached a value of 792% and 82%, respectively. The best chewiness was found for an oleogel containing olive oil, whereas oleogels with the other two tested oils showed better springiness. Hence, the results presented in this work demonstrated that alginate-based cryogels can be effectively used as templates for oleogels and potentially find applications in the food industry.

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.

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.

Improvement of 3D white chocolate printing molding effect with oleogels

This study used oleogels to resolve unsolidified white chocolate in 3D printing. Because white chocolate cannot be shaped during 3D printing, the oleogel system is used to solve this problem. The printing parameters and accuracy in a 3D printing system were investigated by using different oleogels added to white chocolate as a material to enhance chocolate extrusion solidification, monoglycerides (MAG), sucrose fatty acid ester (SE) and hydroxypropyl methylcellulose (HPMC), and their effects on rheological characterization, bridging experiments, and optimal print parameters (material formulation, nozzle height, layer height and print speed) were compared. In the rheological analysis, the viscosity recovery was more than 80% for the HPMC group and less than 80% for the MAG and SE groups. In the bridging experiment, when MAG and SE were added at more than 2%, the white chocolate could be effectively extruded and solidified, and the bridging distance could be stretched to 10 mm. The suitable printing parameters are a nozzle height of 3 mm, a layer height of 3 mm, and a printing speed of 10 mm/s. This study provides a future solution to solve the problem of extruded unsolidified chocolate.

Plant-based foods as meat and fat substitutes

Animal proteins have in the past been used in food production due to their functional properties that range from gelation and emulsification to foaming ability and stability. However, animal husbandry has been shown to be a major contributor to global warming and climate change. Consequently, there has been a drive toward the use of alternative proteins, for example, proteins from plant sources which are perceived to be cheaper, healthier, and sustainable. The use of trans and saturated fatty acids in the food industry has been associated with various health issues that include an increased risk of metabolic disorders. This has resulted in an increased search for fat substitutes that are healthier and sustainable. To contribute toward a reduction in the consumption of meats from animal sources and the consumption of trans and saturated fatty acids, the formulation of plant-based meat and fat analogs/substitutes has been carried out. However, there has been a lower acceptance of these meat or fat substitutes which was attributed to their sensorial and textural properties that fail to mimic or resemble real fat or meat. Therefore, this review aims to discuss the advances that have been made when it comes to plant-based meat and fat substitutes. Additionally, consumer perception and acceptance of these products will be reviewed as well as future markets will be discussed and the opportunities and challenges that exist in the formulation of these products will be explored.

Emulsion-Templated Liquid Oil Structuring with Egg White Protein Microgel- Xanthan Gum

In this study, oleogels were prepared by the emulsion-template method using egg-white protein microgel as a gelator and xanthan gum (XG) as thickener. The physicochemical properties of the emulsion and oleogels were investigated. The adsorption of protein on the surface of the oil droplet reached saturation when the protein microgel concentration reached 2%. The excess protein combined with XG and accumulated on the outer layer of the oleogel, which prevented the emulsion from flocculation, enhanced the oil-holding capacity of the oleogel, and had a positive effect on preventing the oxidation of oil. When the concentration of XG was less than 0.4%, the EWP microgel, combined with the XG, stabilized the emulsion. As the concentration of XG was greater than 0.4%, excessive XG in the emulsion improved the viscosity and mechanical properties of the emulsion to prevent the aggregation of oil droplets. However, the change in XG concentration had no significant effect on the oxidation of the oil.

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.

Ultrasonic Treatment of Food Colloidal Systems Containing Oleogels: A Review

The use of oleogels as an alternative to solid fats to reduce the content of saturated and trans-isomeric fatty acids is a developing area of research. Studies devoted to the search for methods of obtaining oleogels with given properties are of current interest. Ultrasonic treatment as a method for modifying oleogel properties has been used to solve this problem. The number of publications on the study of the effect of ultrasonic treatment on oleogel properties is increasing. This review aimed to systematize and summarize existing data. It allowed us to identify the incompleteness of this data, assess the effect of ultrasonic treatment on oleogel properties, which depends on various factors, and identify the vector of this direction in the food industry. A more detailed description of the parameters of ultrasonic treatment is needed to compare the results between various publications. Ultrasonic treatment generally leads to a decrease in crystal size and an increase in oil-binding capacity, rheological properties, and hardness. The chemical composition of oleogels and the concentration of gelators, the amplitude and duration of sonication, the cooling rate, and the crystallization process stage at which the treatment occurs are shown to be the factors influencing the efficiency of the ultrasonic treatment.

Structural Characterization and Peroxidation Stability of Palm Oil-Based Oleogel Made with Different Concentrations of Carnauba Wax and Processed with Ultrasonication

The effect of ultrasonication (25 kHz for 10 min) on physical, thermal, and structural properties and storage stability of palm oil-based oleogels prepared using different concentrations of carnauba wax (CW) (5% or 10%) were investigated and compared with oleogels prepared with a homogenizer (2000 rpm for 10 min). Overall, this study found that applying an ultrasonication process with higher CW concentration (10%) effectively improved the properties and stability of palm oil-based oleogel (p < 0.05). Oleogels processed with ultrasonication had higher lightness (L*), higher yellowness (b*), and lower redness (a*) than those processed with homogenizer (p < 0.05), irrespective of CW concentrations. However, a higher CW concentration (10%) increased the textural properties of oleogels such as hardness, stickiness, and tackiness as compared to oleogels with a lower CW concentration (5%) (p < 0.05). Thermal properties including melting onset temperature, melting peak temperature, and melting enthalpy were found to be significantly higher in ultrasonication-processed oleogels with high CW concentration (p < 0.05). Furthermore, the microscopic examination of the oleogels exhibited a strong gel network when prepared using a high concentration of CW and processed with ultrasonication. Fourier Transform Infrared (FTIR) spectra of oleogels revealed that strong intra- and intermolecular interactions were formed by hydrogen bonding between CW and palm oil. X-ray diffraction (XRD) showed a smooth and fine structural network of oleogels and proved that ultrasonication increased the structural properties of oleogel. Moreover, oil loss and peroxide value of oleogels were increased during 90 days of storage (p < 0.05). However, oleogels processed with the ultrasonication had reduced oil loss and increased peroxidation stability during storage (p < 0.05). Overall, this study showed that application of ultrasonication with a higher CW concentration could improve properties and storage stability of palm oil-based oleogel.

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.

Steering protein and lipid digestibility by oleogelation with protein aerogels

The aim of the present work was to assess the effect of an innovative oleogelation strategy, the aerogel-template approach, on protein and lipid digestibility. Whey protein isolate (WP) was converted into aerogel particles via supercritical CO₂ drying. Oleogels were then prepared by absorption of sunflower (SO) or flaxseed (FLX) oil (80%, w/w) into the aerogel particle template and subjected to in vitro digestion. WP aerogel-templated oleogels showed a specific destructuring behaviour during digestion. Confocal micrographs clearly demonstrated that the original oleogel structure was lost at the gastric level, with the release of oil droplets smaller (D₃₂ < 10 μm) than those observed in the case of the unstructured oils (D₃₂ > 30 μm), stabilised by undigested aerogel proteins. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and bicinchoninic acid (BCA) assay confirmed that aerogelation reduced the gastric proteolysis of WP from nearly 100% to 70%. The digestion of the SO oleogel led to similar gastric protein digestibility. In contrast, in the case of the FLX oleogel, gastric proteolysis decreased to 40%, suggesting a role of the oil nature in steering WP aerogel digestion. In all cases, upon intestinal digestion aerogel proteins resulted completely hydrolysed. The lipolysis degree of SO (75%) and FLX (34%) oil in the oleogels was higher than that of the unstructured SO (66%) and FLX (24%) oils, due to the larger surface offered by smaller oil droplets to the action of intestinal lipases. This was confirmed by dynamic light scattering, showing a shift towards smaller size in the digestive micelle distribution of oleogels at the end of the intestinal phase. Oleogelation through the WP aerogel-template approach could be regarded as a strategy to steer lipid digestibility while also modulating the release of bioaccessible peptides.

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.

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.

Plant Proteins for Future Foods: A Roadmap

Protein calories consumed by people all over the world approximate 15-20% of their energy intake. This makes protein a major nutritional imperative. Today, we are facing an unprecedented challenge to produce and distribute adequate protein to feed over nine billion people by 2050, in an environmentally sustainable and affordable way. Plant-based proteins present a promising solution to our nutritional needs due to their long history of crop use and cultivation, lower cost of production, and easy access in many parts of the world. However, plant proteins have comparatively poor functionality, defined as poor solubility, foaming, emulsifying, and gelling properties, limiting their use in food products. Relative to animal proteins, including dairy products, plant protein technology is still in its infancy. To bridge this gap, advances in plant protein ingredient development and the knowledge to construct plant-based foods are sorely needed. This review focuses on some salient features in the science and technology of plant proteins, providing the current state of the art and highlighting new research directions. It focuses on how manipulating plant protein structures during protein extraction, fractionation, and modification can considerably enhance protein functionality. To create novel plant-based foods, important considerations such as protein-polysaccharide interactions, the inclusion of plant protein-generated flavors, and some novel techniques to structure plant proteins are discussed. Finally, the attention to nutrition as a compass to navigate the plant protein roadmap is also considered.

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.