Advanced oleogel and hydrogel systems: emerging platforms for food structuring and targeted nutrient delivery

1 Introduction

The increase in the consumer demand of foods that are functional or healthy is promoting studies in soft materials that have the potential to improve both the nutritional and sensory aspects of food products. Traditionally, the food industry was relied on the use of saturated and trans fats to provide food products with the desired structure, stability, spreadability, and mouthfeel (Patel and Dewettinck, 2015). The consequences of saturated fats and industrially produced trans fatty acids has been linked with heart diseases, obesity and metabolic disorders. Hydrogenation processes, along with the use of tropical oils, like palm oil, have been common practices to provide the desirable texture and stability in food products. Despite of their efficacy, these approaches raise significant ecological and public health challenges (Gravelle and Marangoni, 2018). The consumption of excessive amounts of saturated fats and trans fats has been extensively related to cardiovascular and metabolic disorders. The consumption of saturated fats, which can be naturally found in various animal-originated foods, may lead to an increase in LDL cholesterol, thus posing a risk for atherosclerosis, heart disease and stroke (Mozaffarian et al., 2010; Mensink et al., 2003). Industrially produced trans fatty acids resulting from partial hydrogenation of oils not only contributes in increasing levels of LDL cholesterol but also lowers HDL cholesterol, causing inflammation and endothelial dysfunction (de Souza et al., 2015; Mozaffarian et al., 2006). Prolonged intake of saturated and trans fats contributes in the development of obesity, insulin resistance, type 2 diabetes mellitus, hypertension and cancer (de Souza et al., 2015). These severe health risks have focused global attention on reducing fat consumption and substituting them with healthier options in food formulations (Restrepo and Rieger, 2016).

To account these challenges, healthier and sustainable food structuring techniques have been attracting considerable attention. Oleogels and hydrogels have shown great promise as a new generation of soft matter systems able to structure liquid oils and aqueous phases in a semi-solid state while retaining their chemical structure shown in Figure 1 (Singh et al., 2022). Other than being used for fat replacement, these systems can also be used to control nutrient digestion and improve the release of bioactive substances. Such properties have diversified their application areas beyond food into medicine, biology and cosmetics (Ferro et al., 2021).

Food soft matter systems have complex hierarchical structures varying from molecular to macro-level organization. Food structures at these levels play an important role in determining food materials’ mechanical properties, stability, and digestion behaviors (Almeida et al., 2024). Recent developments in food colloid science have shown that controlling food structures on the microscopic and nanoscopic scales is possible and can be used to modulate nutrient release, lower post-prandial glycemic response and increase the bioavailability of liposoluble substances (Manocha et al., 2022).

Oleogels are semi-solid systems in which edible oils are entrapped into three-dimensional structures that are made up of oleogelators in very small amounts (Marangoni and Garti, 2018). The process of oleogelation is different from hydrogenation which involves a chemical change in the oil molecules, but in oleogelation oils are physically entrapped using a variety of crystalline, fibrillar or polymeric structures. Oleogelation helps to retain the presence of unsaturated fatty acids while offering solid characteristics. Oleogels provides an interesting approach for developing healthier bakery items, spreads, meat substitutes and candy formulations (Abe et al., 2025).

Hydrogels, on the other hand represents three-dimensional structures made up of hydrophilic polymer chains that can hold plenty of water. In food systems, hydrogels are responsible for water stabilization, texture modification and bioactive compound encapsulation. Common used hydrogels in food industries are alginate, carrageenan, pectin, and gelatin owing to their biocompatibility and good gelation efficiency (Kanelaki et al., 2022; Priya et al., 2024).

Recent developments in innovative structuring technologies such as emulsion gel, double network gel and multifunctional delivery systems in food soft matter science have enabled new designs of gel systems featuring tunable mechanical properties, high stability and functional nutrition have demonstrated promising capabilities in controlling digestion kinetics and improving nutrient bioavailability (Obayomi et al., 2025; Gandhi et al., 2026).

The incorporation of oleogels and hydrogels within food systems showed increase in nutritional value, stability and functionality of food. Researchers have found that the inclusion of oleogels is effective in reducing the amount of saturated and trans fats in foods by providing an equivalent structure in food products (Patel et al., 2014). Oleogels are also beneficial in terms of improved lipid absorption and increased intake of lipophilic components such as carotenoids, phytosterols, curcumin, and omega-3 fatty acids (Singh et al., 2022). Hydrogels also exhibit promising outcomes concerning water binding capacity, stability and controlled release of nutrients. Proteins and polysaccharides-based hydrogels have also been used in probiotics, vitamins, antioxidants and active compound delivery systems (Ahmed, 2015; Ferro et al., 2021).

In this review paper, recent advancements in oleogels and hydrogels will be discussed with particular attention given to structuring principles, digestion properties and applications of these systems as nutrient delivery carriers in next-generation nutritional foods.

2 Structuring mechanisms of oleogels and hydrogels

The structure of the material influences the performance of the oleogel and the hydrogel in food applications. The formation of three-dimensional networks by means of chemical interactions determines how oil gets entrapped in the oleogels and water in hydrogels. It is necessary to know this mechanism so that you can control other properties (Okuro et al., 2021).

2.1 Structuring mechanisms in the formation of oleogels

Oleogels are created through the immobilization of a liquid oil in a self-assembled or polymer-induced structure. In contrast to regular solid fats, which depend on highly saturated fatty acids for crystal formation, oleogels create structures out of unsaturated oils without changing the fatty acid profile. The process of structuring is mostly dictated by the oleogelator that is being used for the formation of oleogels. Oleogels are organized structures of liquid oil immobilized within a three-dimensional network formed by gelators through direct and indirect method shown in Figure 2 (Zhao et al., 2026).

2.1.1 Low molecular weight gelators (LMWGs)

Low molecular weight gelators (LMWGs) are defined as small molecules with a molecular weight less than 2000 Da which have the property of self-assembling to form a highly ordered three-dimensional network in aqueous solution using weak non-covalent interactions. Such non-covalent interactions are usually hydrogen bonds, van der Waals force, π–π stacking, electrostatic interactions and hydrophobic interaction. Contradictory to the polymer gels, LMWGs do not need covalent crosslinking in order to generate gel networks they solely depends on molecular aggregation under favourable environmental conditions (temperature, pH, or concentration) to construct a gel matrix (Terech and Weiss, 1997; Li et al., 2025).

Dissolution of LMWGs in solvents subsequently followed by cooling or exposure to specific triggers, the molecules aggregate to produce supra-molecules such as fibrils, fibers, ribbons, helices or crystals. Then the supra-molecular aggregates continue to entangle each other to produce a three-dimensional network in the liquid matrix. As a result, the molecules in liquid matrix are entrapped in between the three-dimensional network, producing gelling effect to transform liquid to semi-solid or solid gel network. This process is known as supramolecular gelation (Liao et al., 2021).

Gelation efficiency of LMWGs is greatly affected by the molecular structure of these compounds, polarity, concentrations, and types of intermolecular interactions. Amphiphilicity is a widespread feature of most LMWGs since both hydrophilic and hydrophobic groups allow for molecular clustering and entrapment of solvents. LMWGs have significant value in structuring edible oils into oleogels through maintaining the chemical integrity of the oils used (Patel and Dewettinck, 2015; Ohsedo and Takagi, 2024).

Various LMWGs produce different supramolecular structures, for instance, crystals formed by waxes form crystalline platelets, while β-sitosterol and γ-oryzanol mixtures produce tubular fibrillar structures stabilized by hydrogen bonding interactions. The type of architecture significantly affects rheology, thermal stability, oil affinity, and texture of gels (Rogers et al., 2009; Blake et al., 2014). Therefore, the outstanding capability of LMWGs to self-assemble and trap the solvent molecules makes these materials suitable for designing unique soft-matter systems and structured fats in the food and biomedical industries.

2.1.2 Polymeric gelators

Polymeric gelators are macromolecules that have the capacity to immobilize liquids via the creation of a three-dimensional interconnected polymeric network. As opposed to LMWGs, which are mainly stabilized by spontaneous formation of supra-molecular assemblies using weak non-covalent forces, polymeric gelators immobilize liquids using processes like chain entanglements, hydrogen bonding, electrostatics, hydrophobic associations and chemical and physical crosslinking between polymer chains (Pal et al., 2025). Consequently, the network traps substantial quantities of solvents within the polymer structures thus immobilizing the liquid medium.

Polymeric gelators can originate from natural, semi-natural, or synthetic sources. They are commonly used in hydrogels and oleogels due to high stability, good biocompatibility, and desirable rheological behavior. Biopolymers derived from cellulose, alginate, pectin, chitosan, starch, gelatin, soy protein and whey proteins have been extensively researched polymeric gelators for applications in food and pharmaceutical industries (Abe et al., 2025; Sharma et al., 2025). Such polymers are characterized by several functional groups that allow for intermolecular interactions and networking in specific environmental parameters such as temperature variations, pH differences, salt concentrations and solvents used.

In general, LMWGs and polymeric gelators can be seen as two different ways of structuring soft materials. The use of LMWGs involves efficient structuring of oils using their properties of self-assembly and crystallization, while polymeric gelators benefit from their ability to provide better stability and resistance owing to the polymer network that is formed. Table 1 contains the distinguishing characteristics of LMWGs and polymeric gelators. Modern studies are more interested in the development of novel generation hybrid gels combining properties of both classes of compounds.

TABLE 1. Comparative analysis of low molecular weight gelators (LMWGs) and polymeric gelators.

2.1.3 Mechanisms in the formation of oleogels

This involves self-assembly of the gelator into fibrillar networks or crystalline domains that entrap oil by capillary forces and physical entanglements, transforming a fluid into a solid-like structured matrix (Han et al., 2026).

2.1.3.1 Crystallization driven gelation

One of the most prevalent methods requires the crystallization of low molecular weight oleogelators (LMWOGs), which include waxes, fatty acids, fatty alcohols and mono-glycerides. This method begins with the dissolution of the oleogelator in an oil phase at high temperatures afterwards, nucleation occurs due to some thermodynamic stimuli (such as cooling or concentration) that force the alignment of chain segments shown in Figure 3. This nucleus starts out small and then grows larger when other chain segments adopt its crystalline structure. Several different nuclei form. The crystalline domains become physically entangled through the intervening chain segments. This creates a 3-dimensional meshwork known as the gel structure. These crystals cluster together to create a network structure that encapsulates oil in the voids by capillary action (Han et al., 2026). The properties of the resultant oleogel rely heavily on the morphology of the crystals, polymorphism of the oleogelator, cooling speed, and oleogelator concentration. This type of mechanism has been reported by the researchers and they highlighted the role of crystal–crystal interactions in oil immobilization (Zhang et al., 2023).

2.1.3.2 Self-assembly and fibrillar network formation

Some oleogelators generate gels by means of self-assembly and not by means of classical fat crystal formation. This is achieved by the interaction of small molecules with each other by means of non-covalent bonds such as hydrogen bonding, vander waals forces and π-π interaction (Rogers, 2014). This forms a directional bonding network leading to the formation of long fibers that entangle together, forming a 3D network that immobilizes oil. The ratio of the gelator - gelator and the gelator - oil interaction decides whether stable fibrils will be formed or not. In such cases, the formation of the gel is through non-covalent self-assembly of molecules, which can be hydrogen bonding, π-π interaction and van der Waals forces shown in Figure 4 (Contreras-Montoya et al., 2024; Wijarnprecha et al., 2018).

2.1.3.3 Polymeric network formation (indirect method)

Polymers having high molecular weights (e.g., proteins and polysaccharides) cannot dissolve in oil and hence, indirect structuring methods have to be used for them. Indirect methods create a covalently linked polymer matrix in two stages: first, the precursor polymer is prepared, followed by a second-stage cross-linking process that happens apart from the synthesis process, usually following the processing and/or molding of the polymer (Figure 5). This cross-linking may be achieved through chemical means (such as glutaraldehyde and carbodiimide coupling), enzymatically (using transglutaminase), radiatively (with ultraviolet or gamma rays), or through the use of existing functional groups in the polymer. This technique entails making a hydrogel or emulsion template, after which the aqueous phase is removed or replaced. The polymeric gel framework stays undisturbed, while the oil is physically entrapped in it (Pinto et al., 2021; Bascuas et al., 2020).

2.2 Structuring mechanisms in hydrogel formation

The hydrogels can be defined as a three-dimensional hydrophilic polymeric network that is able to retain significant amounts of water inside its structure without undergoing dissolution. Like oleogels, the process of hydrogel synthesis is also determined by the nature of the gelator employed and the type of intermolecular interactions that predominate during hydrogel assembly (Bustamante-Torres et al., 2021). Formation of hydrogels occurs via creation of the continuous polymeric network as a result of the process of cross-linking. The behavior of the resulting hydrogel will depend on many factors. The hydrogelators can be categorized as natural, semi-synthetic and synthetic polymers, based on the mechanism of structuring through physical/chemical crosslinking shown in Figure 6 (Mehta et al., 2023).

2.2.1 Polysaccharide based hydrogelators

Polysaccharide based hydrogels are high molecular weight carbohydrates with three-dimensional hydrated polymer networks with the ability to absorb substantial quantities of water. As they are derived from nature and are biodegradable, non-toxic and approved for food system use, polysaccharides are the most extensively utilized hydrogels in food science and nutrient delivery processes (Nath et al., 2022).

Polysaccharides contain numerous hydrophilic functional groups like hydroxyl (–OH), carboxyl (–COOH) and sulfate (–SO₄ ^2-). The functional groups allow interaction among chains by hydrogen bonding, electrostatic interactions, and chain entanglement. Polysaccharides used as hydrogelators may be linear or branched and can be neutral or charged. Their gelation behavior depends on monomer composition, molecular weight, degree of substitution or acetylation, charge density, polymer concentration. Common polysaccharide hydrogelators include alginate, pectin, carrageenan, agar and cellulose derivatives (e.g., CMC, HPMC) (Bustamante-Torres et al., 2021). Hydrogels from polysaccharides considered as GRAS (Generally Recognized as Safe) approved. Alginate hydrogels that are obtained through ionic cross-linking using calcium ions are often utilized to encapsulate probiotics, vitamins, flavors, and other bioactive agents. In the beverages industry, alginate is used to formulate encapsulated fruit juices, flavored pearls, and probiotic carriers. This helps maintain stability and controlled release of nutrients within the body (Li et al., 2025).

Pectin hydrogels are often used in jams, jellies, fruit fillings, and low-sugar foodstuffs due to their high gelling and water binding ability. Carrageenan hydrogels are used in dairy products like chocolate milk, yoghurt, and desserts to increase their viscosity, prevent separation, and improve their mouthfeel. On the other hand, agar and gellan gum are commonly used in candy preparations, vegetable products, and dessert gels due to their good ability to form gel and thermal stability (Patel et al., 2024).

2.2.2 Protein based hydrogelators

Hydrogelators that rely on protein molecules are biopolymer-based materials that can generate three-dimensional water-filled structures through denaturation, aggregation and intermolecular binding processes. As proteins are amphipathic, nutritionally rich and functionally flexible compounds and they also find application as hydrogelators in food engineering and formulation applications (Lee et al., 2023).

Proteins possess a variety of functional groups including amino groups (–NH₂), carboxyl groups (–COOH), sulfhydryl groups (–SH) and nonpolar residues that facilitate hydrogen bonding, hydrophobic bonding, ionic interactions and covalent disulfide bonding respectively. Gelation behavior depends on amino acid composition, tertiary and quaternary structure, pH relative to isoelectric point (pI), ionic strength, temperature and protein concentration. Common protein hydrogelators include gelatin, whey protein isolate, soy protein isolate and casein (Bashir et al., 2020). Gelatin hydrogels find widespread application in gummies, marshmallows, confectionery items, and nutraceutical pharmaceuticals due to their thermo-reversible nature as well as their pleasant sensory characteristics. Whey protein hydrogels are becoming popular in the development of functional foods and beverages, where they are used as carriers for bioactives, antioxidants, and probiotics. Protein hydrogels made from soy protein and pea protein are finding significant applications in plant-based meat and dairy alternatives as they provide suitable sensory characteristics and structural integrity. Protein hydrogels also provide an option to improve the sensory characteristics and act as carriers for vitamins and other nutraceuticals (Colin et al., 2024).

2.2.3 Synthetic polymer hydrogelators

Artificially synthesized hydrogels of polymer hydrogelators consist of synthetic macromolecules that possess the ability to form three-dimensional structures in which large quantities of water can be entrapped. In contrast to naturally occurring biomacromolecules, the synthetic polymers have a high level of predictability in terms of their molecular structure, mechanical properties and sensitivity to various stimuli are concerned. The synthetic polymers usually have functional groups like hydroxyl (-OH), amide (-CONH-), carboxyl (-COOH) and vinyl groups that facilitate controlled cross-linking. The main cross-linking in the synthetic polymers takes place chemically but generally physically formed bonds are employed (Bustamante-Torres et al., 2021; Thang et al., 2023).

Despite the rare use of synthetic hydrogels in food products, due to regulatory concerns, food-grade synthetic hydrogels like PVA-based hydrogels and PEG-based hydrogels find uses in food packaging and controlled release systems. These substances can be useful for increasing moisture retention, improving shelf life, and facilitating the controlled delivery of preservatives and antimicrobials. Synthetic hydrogels are also being considered for the development of smart food packaging that is able to detect food quality (Machado et al., 2025). Different type of hydrogel and their functional properties with food application summarized in Table 2.

TABLE 2. Classification of hydrogels and their food industry applications.

2.2.4 Mechanisms in the formation of hydrogels

The mechanism of hydrogel formation mainly depends on polymer type, environmental conditions and the nature of crosslinking interactions. Hydrogel formation mechanisms can be classified on the basis of basis of bond formation into physical crosslinking and chemical crosslinking processes in Figure 7 (Li et al., 2021).

2.2.4.1 Physical crosslinking mechanisms

Physical hydrogels are synthesized using reversible non-covalent interactions and may be referred to as “reversible” or “temporary” gels since their gel-like state can be broken by variations in external factors such as pH, temperature, and ionic strength (Goswami et al., 2025).

Hydrogen bonds: They are formed between hydrogen deficient atoms and electronegative atoms like oxygen and nitrogen, for example, hydrogel formation occurs for carboxymethyl cellulose and polyvinyl alcohol via extensive hydrogen bonding.

Ionic bonds: Positively charged polymers such as chitosan can react electrostatically with negatively charged molecules like sulfates, phosphates, citrates, or even other anionic polymers like alginate crosslinking through Ca⁺² ions in the “egg-box” structure to form a physical network.

Hydrophobic interactions: Amphiphilic polymers (with both water-loving and water-hating parts) can aggregate in water. Hydrophobic domains will try to cluster together avoiding contacts with water, which makes them physical junctions for hydrophilic domains (Knipe and Peppas, 2014).

Physical hydrogels are made up of non-covalent forces such as hydrogen bonds, ionic forces, hydrophobic forces, and chain entanglements. Even though these hydrogels provide good biocompatibility due to the absence of covalent cross-linkers, which can be toxic chemicals, these physical hydrogels suffer from low mechanical properties owing to weak molecular interactions. Physical hydrogels have been found to be very sensitive to the environment, and any changes in temperature, pH, ionic strength, and water concentration can cause swelling, shrinkage, syneresis, or premature degradation of these hydrogels (Hu et al., 2022). Physical hydrogels may not have sufficient strength to endure mechanical stresses during manufacturing, transportation, and storage in food products. Moreover, since the physical hydrogels have reversible structures, they are less stable when compared to other hydrogels.

2.2.4.2 Chemical crosslinking mechanisms

Chemical hydrogels consist of permanent covalent bonds. They are known as “permanent” hydrogels due to the fact that the gel network cannot be reversed without breaking the chemical bonds of the polymer backbone. They are classified into different types on the basis of the crosslinking agents that is being used for the formation of hydrogels (Hense and Strube, 2024).

Chemical grafting: It uses a cross-linker such as glutaraldehyde that interacts with functional groups like amino or hydroxyl functional groups of two different polymer chains and “links” the two chains together by forming a bridge.

Polymerization and Cross-linking: Monomers polymerize under the action of a cross-linking agent that contains at least two double bonds such as N, N′-methylenebisacrylamide. The cross-linking agent becomes an integral part of the developing chains and helps in the cross-linking process (Ahmed, 2015).

Radiation induced cross-linking: Hydrogels can be prepared using high energy radiations like gamma rays or electron beams, which generate free radicals. The free radicals help in cross-linking by forming covalent C-C bonds between polymer chains. This is considered safer than the conventional chemical route as it does not generate any toxic chemicals (Fekete et al., 2017).

Enzymatic cross-linking: It employs enzymes such as transglutaminase to help in cross-linking reactions where covalent bonds are formed between particular groups (amine and carboxyl groups) present in the chain (Teixeira et al., 2012; Da et al., 2011).

Table 3 is showing distinguishable properties of physical and chemical hydrogels on the basis of different characteristics. The covalently bonded networks of chemical hydrogels confer greater stability and strength on such gels. Nonetheless, the process of creating such networks requires the use of chemicals such as cross-linkers and other reagents that may remain within the end product, thereby increasing safety issues with regards to toxicity and biocompatibility (Du et al., 2015).

TABLE 3. Comparative analysis of physical and chemical hydrogel networks.

3 Physicochemical properties and characterization

This section explains how oleogels and hydrogels are analyzed and how their physicochemical features influence functionality, stability and performance in food matrices. Figure 8 is providing a outine of the physicochemical properties that are significant for modified gels and their characterization (Werner-Cárcamo et al., 2024; Xiong et al., 2025).

3.1 Rheology and texture

Rheology and texture provide insights into the mechanical characters of the gels and how it responds to stress and what it feels like when consumed. While rheology deals more with the flow and deformation of the matrix, the storage modulus (G′) can be used to characterize the structural integrity of the gels and thixotropy to indicate how rapidly it comes back together after spreading or 3D printing. However, the textural qualities of hardness, chewiness or springiness of the gels can be described using texture profile analysis (TPA). Rheology and texture thus enable gels to exhibit desirable properties of “snap” in chocolate or “juiciness” in meat analogs while maintaining long-term physical stability against oil or water leakage (Werner-Cárcamo et al., 2024).

3.2 Microstructure and stability

Oleogels and hydrogels have a microstructure that includes three-dimensional networks that trap oil or water in crystals, fibers, or cross-linked polymers. The oil binding ability in oleogels is defined by the size and geometry of the crystals used, as well as their interaction with each other. For hydrogels, pore sizes and the amount of cross-linking affect their ability to retain water. These materials can be analyzed using parameters like oil leakage, syneresis, oxidative stability, and structural stability under storage conditions. By utilizing advanced imaging like Cryogenic Scanning Electron Microscopy (Cryo-SEM) or Polarized Light Microscopy, researchers can optimize these micro-architectures to ensure the food matrix remains robust during long-term storage and temperature fluctuations (Ropciuc et al., 2024).

From Table 4 it is important to note that the rheological and textural properties of oleogels and hydrogels depend significantly on the structuring technique used. As can be seen, crystalline oleogels tend to be harder than other types because of the dense structure of crystals, while polymers and emulsion-based oleogels are more flexible and have improved spreadability. Likewise, chemical and composite hydrogels are better in terms of gel strength and elasticity compared to physical hydrogels.

TABLE 4. Influence of structuring techniques on rheological and textural properties of oleogels and hydrogels.

3.3 Quantitative evaluation of physicochemical properties of hydrogels

Properties of hydrogels can be studied via rheology testing, texture profiling, water binding, swelling, and stability. As a rule, the storage modulus (G′) and loss modulus (G″) are used to determine the strength of gels and their viscoelasticity. Well-structured hydrogels have a higher storage modulus than loss modulus (G′ > G″) indicating that the system has more elasticity to retain its structure under stress (Li and Mooney, 2016).

There is a strong dependence between the structure of hydrogels and its functionality (Table 5). For example, alginate-based hydrogels are highly effective in water retention and probiotic encapsulation due to which these materials are applied to develop new carriers for probiotics, flavorsand active substances (Colin et al., 2024). Protein-based hydrogels, such as gelatin and whey proteins, can offer appropriate textures and viscoelasticity while the combination of proteins and polysaccharides may result in better stability and mechanical properties (Ćorković et al., 2021). Also, biopolymer hydrogels can demonstrate high water binding capacity and adjustable physical-chemical properties which make them promising food structuring agents (Patel et al., 2024).

TABLE 5. Representative physicochemical characteristics and applications of commonly used food-grade hydrogels.

4 Advances in digestion modulation of structured gels in gastrointestinal conditions

Structured gels that are oleogels and hydrogels not only have modified textural properties but they significantly impact the kinetics of lipids and nutrient digestion and metabolism. Current studies are moving from simple structure analyses to investigating the relationship between network structures and digestion processes (Han et al., 2026). Mechanisms of advanced digestion modulation in modified structured gels are represented in Figure 9.

4.1 The cage effect

In standard emulsions, the lipid droplets are quickly exposed to pancreatic lipase causing rapid digestion and sudden peaks in the triglyceride level in the bloodstream. The formation of a physical barrier like a cage around the droplets by the use of structured gels causes what is called the “cage effect” (Co and Marangoni, 2012).

Steric Barrier: The densely packed lattice structure of either wax particles or LMWOG forms a complex network that restricts the approach of the lipase enzymes to the oil-water interface.

Viscosity Regulation: The highly viscous nature of the internal environment of the oleogel slows down the rate of diffusion of the products more likely free fatty acids out of the matrix, delaying the initiation of appetite signals and increasing the feeling of satiety (Siraj et al., 2015).

Several studies have shown that alginate-chitosan hydrogels have been very effective in protecting probiotics from acidic environments inside the stomach; their viability was greater than 70%, whereas free probiotics had a viability of below 20% (Cook et al., 2012).

4.2 Controlled stimuli sensitive hydrogel delivery

New generations of hydrogels are designed to act as smart transport systems that react to the physiological conditions found in the gastrointestinal tract (GIT) (Knipe and Peppas, 2014).

pH sensitive release: Hydrogels based on polymers such as alginate or pectin maintain their cross-linked structure even in the highly acidic conditions of the stomach (pH ≈ 2), thereby protecting delicate substances, such as probiotics or antioxidants from denaturation. When these gels come into contact with the more neutral pH of the small intestine, they expand or dissolve, releasing the nutrients at the point where they can be effectively absorbed.

Enzymatic degradation: There are some hydrogels made out of polysaccharides which do not degrade under the influence of any human digestive enzymes but rather break down in the colon due to fermentation by the gut microflora (Bustamante-Torres et al., 2021).

Both the cage effect and stimuli-responsive delivery systems have already been tested via in vitro and in vivo experiments, as described in Table 6. Hydrogel-based systems could be utilized for physical encapsulation of nutrients and probiotics, preventing their destruction in the stomach and allowing for controlled delivery within the intestine. Likewise, stimuli-responsive hydrogel matrices will show environment-induced release characteristics, whereas oleogel matrices will regulate lipid digestion through limiting enzymatic action (Koetting et al., 2015).

TABLE 6. Experimental evidence supporting digestion modulation and stimuli-responsive delivery in oleogel and hydrogel systems.

4.3 Enhancing bioaccessibility and micellar solubilization

Not only does structuring help to slow down nutrient release but it is also an effective way to ensure that hydrophobic nutrients such as curcumin, vitamin D, and lycopene will get absorbed. Micellar assembly: While the oleogel is slowly digested, lipids are being steadily released, creating a steady flow of mixed micelles, which is crucial for fat-soluble nutrient absorption. Protection from degradation: Through the “locking” of bioactive molecules inside crystalline or polymeric structures, they are protected against oxidation or degradation in the hostile environment of the upper gastrointestinal tract (Mehaney et al., 2025).

4.4 Bigels used for multi stage kinetic control

Digestive modulation is maximized by bigels, hybrid structures. They possess both an aqueous gel layer and an oil gel layer, thus their kinetics can be manipulated to allow for differential release of nutrients. The kinetic nature of bigels allows it to provide an initial burst of flavor or energy from its hydrogel component in the oral cavity/first part of the gut, followed by a prolonged release of functional lipids several hours later via its oleogel component in the ileum (Francavilla et al., 2023). While the structural influence of bigels on lipolysis kinetics is discussed here, their specific capacity for dual-nutrient delivery is explained in next section. Different strategies and their mechanisms are summarized in Table 7 along with physiological impact on the gut system (Srivastava and Singh, 2025).

TABLE 7. Strategic mechanisms and physiological impacts of structured gel systems.

5 Nutrient encapsulation and targeted delivery

The first principle involved in next-generation structuring is the development of an advanced system that will deliver nutrients not only as food sources but also as delivery systems with high efficiency. The use of oleogels and hydrogels ensures protection of sensitive bioactive molecules from any environmental damage as well as their release at the most efficient place within the GIT. The Figure 10 shows the role played by the encapsulation techniques, the combination of both hydrogel and oleogel components allows for the protection of the bioactive molecules during passage through the stomach, their gradual release and effective transport in the intestine (Islam et al., 2026; Ramos-De-La-Peña et al., 2021).

5.1 Encapsulation strategy

There are several bioactive ingredients present in functional foods, which are highly prone to degradation due to various environmental factors such as oxygen, light, moisture, pH changes, and high temperature. Oleogels and hydrogels are among the latest technologies used for the encapsulation of these bioactive ingredients. Oleogels for lipophilic bioactives: Vitamin (A, D, E, and K) fat-soluble vitamins, carotenoids, curcumin, phytosterols, and essential oils are few examples of such components that may be added to the oil phase prior to gel formation. The various methods employed for their encapsulation include direct addition, emulsification-oleogelation method, nanoemulsion-based encapsulation, and oleogel-in-water emulsions (Co and Marangoni, 2012; Patel and Dewettinck, 2015). Encapsulation of hydrophilic bioactive compounds: The commonly used carriers for vitamins, phenolics, peptides, enzymes, and probiotics include three-dimensional polymeric networks. Various encapsulation techniques include ionic gelation, extrusion, emulsification-internal gelation, spray-drying followed by hydrogel encapsulation, microencapsulation using hydrogel beads, and stimuli-responsive hydrogel encapsulation. These techniques help protect sensitive molecules from environmental degradation, ensure the viability of probiotics in the gastrointestinal tract, mask off-odors, and promote controlled release in the body (Ramos-De-La-Peña et al., 2021; Puşcaş et al., 2020; McClements, 2015; McClements et al., 2008). Recently, the dual use of oleogels and hydrogels, such as bigels, double-emulsion-based gels, etc., have gained popularity because they make it possible to incorporate both hydrophilic and lipophilic bioactive agents into one formulation, which expands the application possibilities (Suman et al., 2024; Ghinea and Leahu, 2025; Kanelaki et al., 2022).

5.2 Overcoming the gastric barrier

The aggressive environment of the stomach (pH approx 1.5–3) and the presence of proteolytic enzymes may inactivate many bioactive compounds prior to their absorption. Modified hydrogels like those based on calcium alginate or pectin stay contracted in an acidic medium. It makes the gel resistant to the “escape” of its contents while still in the stomach. The change in pH in the small intestine increases to around 6.5–7.0. In response, the gel swells or dissolves due to electrostatic repulsion between negatively charged polymer chains, resulting in targeted release of the encapsulated nutrient directly to the point of absorption (Zhi et al., 2023).

5.3 Improving bioaccessibility and absorption

The “bioaccessibility” describes the fraction of the nutrient that is extracted from the food matrix. A lipophilic compound needs to form mixed micelles along with bile salts and fatty acids in order to pass the aqueous mucus barrier in the intestine. The oleogel helps control the rate of fat digestion, which ensures a timely and coordinated release of both components. Such a “micro-environment” results in enhanced micelle formation and increased absorption by a factor of two. The mesh size or cross-link density of the gel structure can help control the diffusion kinetics, changing the system from a “burst release” type to a “sustained release” type over several hours (Ozorio et al., 2025).

5.4 Bigels: “All-in-one” delivery system

Bigels serve as the epitome of precision delivery systems as they have the capacity to incorporate incompatible nutrients such as Vitamin C (hydrophilic) and Vitamin D3 (lipophilic) into a single encapsulating matrix (Francavilla et al., 2023). A bigel can be designed to release a prebiotic in the upper region of the gastrointestinal tract, while the oleogel phase delivers an antioxidant in the lower regions. Differential release forms an important part of precision nutrition. The Table 8 outlines the functional objectives of structured gel systems by mapping specific matrices to their underlying scientific mechanisms for encapsulation and targeted delivery (Rezaei et al., 2025).

TABLE 8. Functional objectives and technical mechanisms of structured gel delivery systems.

6 Applications of structured gel systems in food matrices

The versatile nature of these modified structured gels makes them suitable for use in various foods where they act as healthier alternatives to traditional fats while offering functional advantages. The uses of these gels are typically classified depending on the particular textural or nutritional problem they overcome in traditional foods (Codină and Dabija, 2025). The wide use of these modified gels within various food matrices ranging from baking to candy making to alternative meat products shown in Figure 11 points to the promise they have in fundamentally altering the nutrition profile and texture of processed foods in today’s world without sacrificing taste explained below (Guo et al., 2024).

6.1 Bakery and confectionery products

In baking, the texture and mouth feel associated with crispness of biscuits or flakiness in pastries is usually a result of using saturated shortenings. Oleogels consisting of ethylcellulose or waxes are used to substitute butter or lard in cookies or cakes. This reduces the amount of saturated fats in the food by 80%. Oleogels can also be used to prevent fat bloom formation, whereby liquid cocoa butter is stabilized to make the chocolate remain glossier and heat-resistant (Chen and Cheng, 2025).

6.2 Meat analogs and meat processed foods

One of the major challenges in plant based meats is how well to reproduce the look and “succulency” associated with animal fat. For fat analogs, structured gels have their advantages. By controlling the proportion between oleogels (to give more fat content) and hydrogels (moisture richness), it is possible to produce “white fat” particles, which will not instantly melt and give the “succulence” typical of beef and pork. Another application where oleogels would help is replacing pork back fat in sausages. In this case, it would be possible to substitute animal based saturated fats with vegetable based unsaturated fats such as olive oil or flaxseed oil, thus ensuring a firm texture without loss of emulsification properties (Park et al., 2026).

6.3 Dairy alternatives and spreads

Dairy free food products depend largely on coconut and palm oil, which mainly consist primarily of saturated fats. With the use of bigels (oleogels and hydrogels) from sunflower and canola oil, one can develop margarine and other spreads that are spreadable directly out of the fridge and have low content of trans fats. Hydrogel-oleogels are used as substitutes for casein (protein from milk) in vegan cheeses in order to provide a more even melting effect and healthier composition (Ye et al., 2024).

6.4 3D food printing

These advanced structured gels are ideal “inks” for 3D printing of various foods because of their particular rheological properties. These gels are characterized by shear thinning effect that is flow under pressure but do not flow in a stationary condition, which allows us to obtain various customized shapes (Drozdov and Christiansen, 2024). The printer can precisely insert a certain nutrient content into these “ink droplets” and produce snacks that will correspond to specific personal needs. Edible films made of hydrogels can be placed on the surface of fruits. The coating based on the hydrogel film sprayed over strawberries or avocados increases their shelf life compared to those without the film layer. Table 9 highlights the different functional roles of structured gel systems in different food industry, explaining how specific matrices enhance both nutritional and sensory profiles (Zhou et al., 2025).

TABLE 9. Applications of structured gel systems in food product modification.

7 Challenges and future prospects

7.1 Commercialization challenges, regulatory considerations and future perspectives

Even though the technology of developing oleogels and hydrogels has demonstrated promising results at lab scale level, it still faces some issues when it comes to their large-scale production. These issues may be attributed to the complexity of scale up, where precise thermal control and specific conditions involving the suitable type of gelators and complex stages involved in development. Batch variability of natural gel forming agents in terms of rheology, strength and encapsulation efficiency is another concern that makes oleogels inconsistent in their properties. Another challenge lies in consumer acceptability, where oleogels may potentially replace saturated and trans fats. However, factors like change in mouth feel, sensory properties, taste and release of flavors can affect the consumer’s choice. Regulatory issues are another barrier to commercialization, where novel gel formulations need safety evaluation concerning toxicity, digestibility, potential allergens, migration capacity and consumer exposure. Oleogel systems are evaluated by GRAS (United States) and EFSA (E.U.) before obtaining regulatory approvals (Silva et al., 2023; Scharfe and Flöter, 2020; McClements, 2020).

Despite numerous reports on enhanced bioactivity and delivery performance, few have explored the techno-economical aspect. Thus, future research should combine performance with techno-economical assessment. Many hydrocolloids, including alginate, pectin, carrageenan, gelatin and xanthan gum, are already approved as GRAS compounds. Nonetheless, new delivery methods will need a thorough assessment process prior to their commercial implementation (Gao et al., 2024).

The future trends may include personalized nutrition, 3D printing of foods, hybrid bigel systems, targeted delivery of bioactives, sustainable gels made from agricultural waste, artificial intelligence-based formulation, and clinical applications. Implementation of these technologies would require a sequential approach from lab-scale production through in vitro digestibility studies to pilot scale and clinical trials (Alkalbani et al., 2026; Qin et al., 2025).

8 Discussion

New generation oleogels and hydrogels are emerging as a new frontier for food structuring, extending texturization to multifunctional food ingredients that also have the potential for digestive manipulation and nutrition targeting. By fusing concepts from materials science and food chemistry, it is now possible to create rationally designed structured gels that function like fat but have improved nutritional value (Co and Marangoni, 2012; Scharfe and Flöter, 2020).

Oleogels and hydrogels are three-dimensional networks of self-assembly structures that physically trap liquid oil within crystalline structures, or organised networks of microfibrils or cross-linked polymer chains. There have been significant advances in the use of low molecular weight oleogelators, high molecular weight gelators and in the synthesis of hybrids that combine the benefits of both classes of gelator. Significant variations in oleogel mechanical properties, oil content and release, are generated through small changes in the concentration of the gelator, cooling rate and cross-linking degree (Smith, 2024; Peixoto et al., 2026).

The potential of structured gels to beneficially affect digestion in the gastro-intestinal tract has been explored. By manipulating lipid solubility and controlling the swelling and erosion of the gels, it is possible to modulate access of lipids to pancreatic lipase, with resulting controlled digestion. This study highlights the potential of such systems for management of diseases related to metabolism, such as managing glycemic levels, inducing feelings of satiety and lowering postprandial lipemia. A major scientific challenge lies in the conversion of in vitro digestion data to in vivo human intake and metabolism effects. In addition, for nutrient delivery encapsulation, structured gels have gained attention. In this context, oleogels are suitable for delivering lipophilic bioactives (carotenoids, fat-soluble vitamins, omega-3 fatty acids), whereas hydrogels are effective encapsulants for hydrophilic compounds (proteins, probiotics, phenolics). Furthermore, so-called bigels, hybrid systems, have recently been developed, which are capable of delivering simultaneously both lipophilic and hydrophilic nutrients from a single delivery system. Even though first products are available, challenges need to be overcome. These include upscaling, storage stability, oxidative stability and especially consumer acceptance. Moreover, food industry and consumers are driven by regulatory affairs and the clean label trend, which may restrict the use of gel systems that are based on synthetically produced or largely altered food ingredients (Peixoto et al., 2026; Okonkwo et al., 2022).

9 Conclusion

This review gives an in-depth discussion of oleogel and hydrogel systems as new materials in soft matter with considerable promise in revolutionizing food technology and bioactive food systems. Through a critical analysis of gelation methods, structures, physiochemical properties, effects on digestion, and applications, this review discusses how these systems can contribute towards tackling some problems associated with fat replacement, nutrient delivery, and food sustainability. While other reviews concentrate on structural functionality of gel-based systems, this review explores recent progress in supramolecular assembly, polymer network formation, stimulation-responsive systems, and digestion-modulating systems. Specific attention has been devoted to the importance of hydrogels and oleogels in modulating the rate and extent of nutrient delivery and bioavailability. Among other topics, this review identifies some limitations of gel-based systems, such as mechanical instability, difficulty in processing, regulatory constraints, lack of scalability, and lack of clinical research. These problems should be addressed by collaboration within different groups of researchers working in the field of food sciences.

In summary, oleogels and hydrogels appear to be a new and rapidly developing field of food soft matter research. Their capacity to integrate structural function with nutritional benefits makes them potential materials for advanced food products, personalized nutrition approaches, and and sustainable food manufacturing systems. Continued innovation in formulation, characterization, regulatory approval, and clinical validation will be essential for translating laboratory advances into commercially viable food products.

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Footnotes

Edited by: Lilia Zago, Rio de Janeiro State University, Brazil

Reviewed by: Andi Febrisiantosa, Indonesian Institute of Sciences, Indonesia

Hridyesh Pandey, Anand Agricultural University, India