Effect of different oleogelators on lipolysis and curcuminoid bioaccessibility upon in vitro digestion of sunflower oil oleogels

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

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

Fabrication of composite gels based on soy protein isolate and κ-carrageenan and delivery of riboflavin: insights into microstructure, gel properties and digestive characteristics

BACKGROUND

Riboflavin, a water-soluble vitamin, is not synthesized in the human body. Hence, developing riboflavin carriers that can be retained in the gastrointestinal system for longer periods can facilitate riboflavin supplementation.

RESULTS

The present study aimed to prepare a soy protein isolate (SPI)-κ-carrageenan composite gel-mediated riboflavin delivery model. Additionally, the effects of different concentrations of κ-carrageenan on the micromorphology, gel strength and rheological properties of SPI gels were investigated. The results showed that incorporating high- concentration of κ-carrageenan (0.4 g kg-1) effectively enhanced the interactions among SPI aggregates, increasing the gel frontal strength to 128.65 g and water-holding capacity up to 81.67%. Additionally, κ-carrageenan incorporation enhanced the gel network structure, reduced gel porosity and increased the density of the gel network structure. Compared with SPI gels, SPI-κ-carrageenan composite gel facilitated the targeted release and in vivo degradation of riboflavin, at the same time as delaying the biodegradation of riboflavin in stored gels.

CONCLUSION

Altogether, the findings of the present study provide insights into SPI-κ-carrageenan composite gels regarding gel properties and interaction mechanisms, as well as a strategy for the slow release of riboflavin in the gastrointestinal tract. © 2025 Society of Chemical Industry.

Engineering crystal network of supramolecular Oleogel via kinetical regulation for improved lutein bioaccessibility

This study presented an approach for controlling supramolecular oleogel crystal network by regulating kinetical factors - specifically, a combination of cooling temperature and aging period. Results indicated that only under long aging period, supramolecular oleogels prepared at different cooling temperature exhibited distinct crystal morphology compared to those under short aging period. The physicochemical properties of oleogels were affected by different crystal networks. Therefore, further research on oleogels under longed aging was explored. For lutein encapsulation, it was observed that supramolecular oleogels with denser crystal network exhibited higher lutein bioaccessibility. This was probably because the denser crystal network providing a solid physical barrier that effectively protected lutein unaffected by gastric acid degradation. Additionally, the micellar capacity was also enhanced to accommodate lutein due to release of long chain fatty acid from the gelator glycerol monostearate (GMS). Collectively, kinetical factors regulation facilitated rational design of oleogels for delivery of lipid-soluble bioactive compounds.

Replacement of backfat with vegetable oils or their oleogels in emulsion-type sausage significantly change the digestibility of meat protein

Replacing animal fat with vegetable oil occurred extensively in the meat products, but whether these replacements will affect the nutrition of meat protein was seldom revealed. Effect of substitution of back fat (BF) by vegetable oils or their oleogels in emulsion-type sausage on the digestion process of meat protein was investigated. Replacement of BF with vegetable oils and their oleogels decreased the G'/G" values of meat paste, and oleogels largely weakened the structure of sausages. The substitution significantly reduced the liberation of -NH2 during the initial gastric and intestinal digestion, and resulted in bigger digests in CLSM images. The reduced gastric digestibility induced by substitution was shown to be related to the reduced stability of gastric digests, which can be attributed to the larger particle size and reduced viscosity of digests. These results highlighted stability of digests as a key point changing the digestion process of meat protein.

Preparation of soybean protein isolate-ester emulsifier oleogels and comparative study of their structure and properties

In recent years, oleogel as a viscoelastic semi-solid to replace trans fatty acids and reduce saturated fatty acids in food has received more and more attention. Herein, an emulsion template method was used to produce soybean oil-based oleogels with seven different ester emulsifiers and soy protein isolate as oleogelators. The chemical and physical characteristics of oleogels produced via various crosslinking factors were comparatively examined. Results revealed that all oleogels generated β-type needle crystals and exhibited high oil-holding capacity (>80 %), among which glycerol monolaurate G2 and diacetyl tartaric acid ester of mono-diglycerides G6 exhibited the strongest oil-holding capacity (96.6 % and 96.2 %, respectively). Furthermore, all oleogels exhibited strong thixotropic recovery, high thermal stability, as well as high gel strength (G' > G''). Of these, G2 and G6 exhibited the highest thixotropic recovery rates at 74.54 % and 78.19 %, respectively. Additionally, in accelerated oxidation trials, the peroxide value and thiobarbituric acid reactive substances of all oleogels had low oxidation rates, indicating high oxidative stability. These results contribute to a better understanding of oleogels for formulating trans-free and low-saturated foodstuffs with desired physical and functional properties.

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.

Effect of different oleogelators on physicochemical properties, oxidative stability and astaxanthin delivery of macadamia oil-based oleogels

Oleogels can be formed using different types of oleogelator, which lead to different end properties. In this study, four kinds of oleogelators, rice bran wax (RBW), monoglyceride stearate (MG), beeswax (BW), and a mixture of β-sitosterol and γ-oryzanol (SO) were used to prepare astaxanthin-loaded macadamia oil-based oleogels. Fourier transform infrared spectroscopy, polarized light microscopy, X-ray diffraction, differential scanning calorimetry, and dynamic shear rheometry were then used to evaluate the effects of the different oleogelators and astaxanthin on the physicochemical properties of the oleogels. The results showed that van der Waals forces played a key role in the formation of all the oleogels, while hydrogen bonding was also important for the SO- and MG-based oleogels. Moreover, astaxanthin addition did not change the crystal morphology and intramolecular interaction forces of the oleogels, but it did increase their oxidative stability and decrease their thermal stability, hardness, and oil-binding properties. In addition, the digestive behavior of the oleogels was evaluated using a three-stage in vitro gastrointestinal model. All the oleogelators significantly affected the lipolysis of the macadamia oil and the bioaccessibility of the astaxanthin, with the degree of lipolysis being positively correlated to the bioaccessibility. MG-based oleogels were the most effective at increasing the bioaccessibility of the astaxanthin.

Investigation of formation of AGEs precursors, hydroxymethylfurfural and malondialdehyde in oleogel added cakes using an in vitro simulated gastrointestinal digestive system

The baking process has the potential to generate health-risk compounds, including products from lipid oxidation and Maillard reaction. Pre- and post-digestion levels of hydroxymethylfurfural (HMF), malondialdehyde (MDA), glyoxal (GO), and methylglyoxal (MGO) were studied in cakes formulated with hazelnut and sunflower oil, along with their oleogels as margarine substitutes. The concentration of HMF in oil and oleogel-formulated cakes increased after digestion compared to cakes formulated with margarine. The MDA values were between 82 and 120 μg/100 g in oil and oleogel formulated cakes before digestion and a decrease was observed after digestion. The substitution of margarine with oil and oleogels resulted in the production of high amounts of GO and MGO in cakes. However, the highest bioaccessibility as 318.2% was found in cakes formulated by margarine for GO. Oleogels may not pose a potential health benefit compared to margarines due to the formation of HMF, MDA, GO, and MGO.

Fabrication, characterization, and in vitro digestion of gelatin/gluten oleogels from thermally crosslinked electrospun short fiber aerogel templates

In this work, the electrospun short fiber-based oleogels (ESFO) were formed by thermal crosslinking. Gelatin and gluten nanofibers were obtained via electrospinning, then homogenized and transformed into short fiber dispersions. Through freeze-drying, electrospun short fiber-based aerogel (ESF-A) templates were obtained for oil adsorption. All ESF-A exhibited the micromorphology of loose fibrous pore structure and prominent changes of characteristic peaks in the thermal and infrared analyses. Moreover, the highly crosslinked templates owned excellent hydrophobicity and mechanical performances (elastic modulus: 0.25 kPa, yield strength: 14.56 kPa, compressive strength: 52.54 kPa, and the final compression recovery: 91.27%). Meanwhile, the oil adsorption/oil holding capacity could reach 76.56 g/g and 80.04%, respectively. Through thermal crosslinking, ESF-O presented good and controllable rheological/in vitro digestion properties, which were further confirmed by PCA analysis. According to different application conditions, ESF-O properties could be adjusted by different degrees of fiber addition or thermal crosslinking.

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

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

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

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

Bioaccessibility, Intestinal Absorption and Anti-Inflammatory Activity of Curcuminoids Incorporated in Avocado, Sunflower, and Linseed Beeswax Oleogels

Beeswax oleogels (OGs), with a mechanical strength similar to pork backfat, were formulated with avocado (A), sunflower (S), and linseed (L) oils, applying a central composite design plus star point, and were evaluated as oral delivery vehicles of curcuminoids (OGACur, OGSCur, OGLCur). The incorporation of curcumin into the OG matrix significantly delayed both the formation of peroxides and conjugated trienes (K268 values), and the degradation rate of curcumin decreased with the increase of the oil polyunsaturated fatty acids (PUFA) content. The oil structuring did not affect the bioaccessibility of curcuminoids (>55% in all the OGs, regardless of the oil type), but it did reduce the release of fatty acids (~10%) during in vitro gastrointestinal digestion. The intestinal absorption, evaluated in Caco-2 cell monolayers, was higher for the micelle-solubilized curcumin from the digested OG than from unstructured oils, and it showed high anti-inflammatory potential by inhibiting the tumor necrosis factor-α (TNF-α) production compared to the positive control, both before and after the stimulation of ThP-1 cells with LPS. Regardless of the oil type, these beeswax-based OGs with gel-like behavior designed as fat replacers may be promising vehicles for the oral delivery of curcuminoids.

Fabrication and Application of Turmeric Extract-Incorporated Oleogels Structured with Xanthan Gum and Soy Lecithin by Emulsion Template

Turmeric extract (TE)-loaded oleogels (TE-OG) was fabricated by an emulsion template technique using xanthan gum (XG) and soy lecithin (SL) as oleogelators. The formulation for TE-OG was optimized using 0.32% XG, 1.2% SL, and 1.0% TE. The optimized TE-OG had a minimal particle size of 810.23 ± 10.68 nm as measured by the dynamic light scattering (DLS) method, and a high encapsulation efficiency (EE) of 96.62 ± 0.56%. Additionally, the optimized TE-OG exhibited a favorable zeta potential of -27.73 ± 0.44 mV, indicating the good stability of the TE-OG due to the electrostatic repulsion between particles. TE-OG formulated with 0.32% XG and 1.2% SL was subjected to frequency sweep testing to evaluate its solid-like rheological behavior. The oil-binding capacity (OBC) of TE-OG was consistently maintained above 99.99%. In vitro digestion of TE-OG demonstrated the potential of the emulsion template for controlled release, with less than 20% of the encapsulated curcumin being released in simulated gastric fluid (SGF), whereas nearly 70% was released in the simulated intestinal fluid (SIF). Moreover, TE-OG affected the rapid release of free fatty acids (FFAs), which have a positive effect on the digestion of triacylglycerols found in soybean oil (SO). TE-OG was further used as an alternative to commercial butter to produce pound cakes, and their rheological properties were compared to those of the pound cake prepared using commercial butter. The pound cake prepared using TE-OG showed a noticeable decrease in hardness from 10.08 ± 1.39 N to 7.88 ± 0.68 N and increased porosity, demonstrating the inherent capability of TE-OG to enhance the overall quality standards of bakery products.

Fabrication of curcumin-loaded oleogels using camellia oil bodies and gum arabic/chitosan coatings for controlled release applications

This study has explored the potential of plant-derived oil bodies (OBs)-based oleogels as novel drug delivery systems for in vitro release under simulated physiological conditions. To obtain stable OBs-based oleogels, gum arabic (GA) and chitosan (CH) were coated onto the curcumin-loaded OBs using an electrostatic deposition technique, followed by 2,3,4-trihydroxybenzaldehyde (TB) induced Schiff-base cross-linking. Microstructural analyses indicated successful encapsulation of curcumin into the hydrophobic domain of the OBs through a pH-driven method combined with ultrasound treatment. The curcumin encapsulation efficiency of OBs increased up to 83.65 % and 92.18 % when GA and GA-CH coatings were applied, respectively, compared to uncoated OBs (63.47 %). In addition, GA-CH coatings retained the structural integrity of oleogel droplets with superior oil-holding capacity (99.07 %), while TB addition induced interconnected 3D-network structures with excellent gel strength (≥4.8 × 105 Pa) and thermal stability (≥80 °C). GA-CH coated oleogels appeared to provide the best protection for loaded bioactive against UV irradiation and high temperature-induced degradation during long-term storage. The combination of biopolymer coatings and TB-induced Schiff-base cross-linking synergistically hindered the simulated gastric degradability of oleogels, releasing only 23.35 %, 12.46 % and 7.19 % of curcumin by GA, GA-CH and GA-CH-TB stabilized oleogels, respectively, while also resulting in sustained release effects during intestinal conditions.

Comparative study on the in vitro digestion of different lipids in starch-based Pickering emulsions

Starch-based Pickering stabilizer has attracted more attentions due to its health-friendly attribute. Lipid digestion in Pickering emulsion is the key to its delivery ability for active substances. Herein, in vitro oral-gastric-intestinal digestions of Pickering emulsions stabilized by starch particles with different oil phases (e.g., coconut, corn, olive, and sunflower oils) were investigated. The highest rate of lipid digestion was coconut oil (25.71 %), followed by olive (12.64 %), corn (11.16 %), and sunflower (8.99 %) oils. The lipid digestibility was influenced by saturation of fatty acids: coconut (91.41 %)>olive (16.58 %)>corn (14.63 %)>sunflower (10.85 %) oils. The increase of starch concentration (0.5 % - 4.0 %, w/w) had positive effects, while the increase of oil fraction (25 % - 70 %, v/v) had negative impacts on free fatty acid release due to the formation of different initial droplet sizes. The microstructures observed using confocal laser scanning microscope indicated that starch-based Pickering emulsion possessed super stability against oral and gastric digestions, which made it a superior delivery system for lipophilic active substances under severe gastric environment. These results may promote the design of functional food emulsions stabilized by starch particles which can regulate digestion of triglycerides.

Influence of the Oil Structuring System on Lipid Hydrolysis and Bioaccessibility of Healthy Fatty Acids and Curcumin

Oleogels (OG) and gelled emulsions (GE) were elaborated with a mixture of olive and chia oils (80:20 ratio) without and with the incorporation of the health-related compound curcumin. These were studied to evaluate the influence of the oil structuring system on the lipid hydrolysis and bioaccessibility of three healthy fatty acids (FA) (palmitic, oleic, and α-linolenic acids) and of curcumin, compared to the oil mixture (bulk oil, BO). The oil structuring system influenced the firmness and texture, and the presence of curcumin significantly altered the color parameters. GE showed higher lipid digestibility, with a greater proportion of absorbable fraction (higher content of free FA and monoacylglycerides) than OG, which behaved similarly to BO. The presence of curcumin affected the degree of lipolysis, reducing lipid digestibility in OG and increasing it in GE. As for FA bioaccessibility, although GE presented higher percentages overall, curcumin significantly increased and decreased FA bioaccessibility in OG and GE, respectively. The oil structuring system also influenced the bioaccessibility of curcumin, which was higher in GE. Therefore, when selecting an oil structuring system, their physicochemical properties, the degree of lipid hydrolysis, and the bioaccessibility of both curcumin and the FA studied should all be considered.

Oleogelation based on plant waxes: characterization and food applications

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

Oleogelation of extra virgin olive oil by different gelators affects lipid digestion and polyphenol bioaccessibility

The possibility to steer extra virgin olive oil (EVOO) digestion and polyphenol bioaccessibility through oleogelation was investigated. EVOO was converted into oleogels using lipophilic (monoglycerides, rice wax, sunflower wax, phytosterols) or hydrophilic (whey protein aerogel particles, WP) gelators. In-vitro digestion demonstrated that the oleogelator nature influenced both lipid digestion and polyphenol bioaccessibility. WP-based oleogels presented ∼100% free fatty acid release compared to ∼64% for unstructured EVOO and ∼40 to ∼55% for lipophilic-based oleogels. This behavior was attributed to the ability of WP to promote micelle formation through oleogel destructuring. Contrarily, the lower lipolysis of EVOO gelled with lipophilic gelators compared to unstructured EVOO suggested that the gelator obstructed lipase accessibility. Tyrosol and hydroxytyrosol bioaccessibility increased for WP oleogels (∼27%), while liposoluble-based oleogels reduced it by 7 to 13%. These findings highlight the deep effect of the gelator choice on the digestion fate of EVOO components in the human body.

Effect of Soy Wax/Rice Bran Oil Oleogel Replacement on the Properties of Whole Wheat Cookie Dough and Cookies

This study investigated the replacement of butter with soy wax (SW)/rice bran oil (RBO) oleogel in varied proportions in cookie dough and the resulting cookies. The study mainly evaluates the physical, textural, and chemical properties of the butter cookie dough and cookies by replacing butter with SW/RBO oleogel. The dough was assessed using moisture analysis, microscopy, FTIR Spectroscopy (Fourier Transform Infrared) and impedance spectroscopies, and texture analysis. Micrographs of the dough showed that D-50 (50% butter + 50% oleogel) had an optimal distribution of water and protein. D-0 (control sample containing 100% butter) showed the lowest impedance values. Moisture content ranged between 23% and 25%. FTIR spectroscopy suggested that D-50 exhibited a consistent distribution of water and protein, which CLSM and brightfield microscopy supported. Texture analysis revealed that the dough samples exhibited predominantly fluidic behavior. As the amount of oleogel was raised, the dough became firmer. The prepared cookies showed a brown periphery and light-colored center. Further, a corresponding increase in surface cracks was observed as the oleogel content was increased. Cookies moisture analysis revealed a range between 11 and 15%. Minute changes were observed in the texture and dimensions of the cookies. In summary, it can be concluded that replacing butter with oleogel by up to 50% seems to be feasible without significantly compromising the physicochemical properties of cookie dough and cookies.

Macadamia oil-based oleogels as cocoa butter alternatives: Physical properties, oxidative stability, lipolysis, and application

In this study, macadamia oil-based oleogels were prepared using monoglyceride stearate (MG) as a gelator with a low critical gelation concentration (3.0 wt%). The physical properties of the oleogels were evaluated by polarized light microscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry, X-ray diffraction, texture and rheological analysis. And the lipid digestion and oxidative stability of the macadamia oil were determined by pH titration and accelerated oxidation test, respectively. The results showed that the hardness, oil binding capacity, and thermal stability of the oleogels increased with increasing MG concentration, which was attributed to the formation of a network of MG crystals held together by van der Waals interactions and hydrogen bonds. Rheological analysis indicated that all the oleogels exhibited a thermally reversible solid-to-liquid transition and viscoelastic behavior at ambient temperatures. Moreover, the formation of oleogels increased fatty acid release during in vitro lipid digestion and improved the oxidative stability of the macadamia oil. In addition, the potential application of these oleogels as replacements for saturated fats in foods was demonstrated by creating a chocolate product where the cocoa butter was replaced with macadamia oil-based oleogels with a high degree of unsaturation. These results can provide guidance for the preparation of macadamia oil-based oleogels, which may increase their application in foods.

Food gel-based systems for efficient delivery of bioactive ingredients: design to application

Food gels derived from natural biopolymers are valuable materials with significant scientific merit in the food industry because of their biocompatibility, safety, and environmental friendliness compared to synthetic gels. These gels serve as crucial delivery systems for bioactive ingredients. This review focuses on the selection, formulation, characterization, and behavior in gastrointestinal of hydrogels, oleogels, and bigels as delivery systems for bioactive ingredients. These three gel delivery systems exhibit certain differences in composition and can achieve the delivery of different bioactive ingredients. Hydrogels are suitable for delivering hydrophilic ingredients. Oleogels are an excellent choice for delivering lipophilic ingredients. Bigels contain both aqueous and oil phases, whose gelation makes their structure more stable, demonstrating the advantages of the above two types of gels. Besides, the formation and properties of the gel system are confirmed using different characterization methods. Furthermore, the changing behavior (e.g., swelling, disintegration, collapse, erosion) of the gel structure in the gastrointestinal is also analyzed, providing an opportunity to formulate soft substances that offer better protection or controlled release of bioactive components. This can further improve the transmissibility and utilization of bioactive substances, which is of great significance.

Comparison of diosgenin-vegetable oils oleogels with various unsaturated fatty acids: Physicochemical properties, in-vitro digestion, and potential mechanism

This study aimed to evaluate the influence of gelation and unsaturated fatty acids on the reduced extent of lipolysis between diosgenin (DSG)-based oleogels and oils with various unsaturated fatty acids. Overall, the lipolysis of oleogels was significantly lower than oils. The highest reduced extent of lipolysis (46.23 %) was obtained in linseed oleogels (LOG) while sesame oleogels possessed the lowest (21.17 %). It was suggested LOG discovered the strong van der Waals force to induce the robust gel strength and tight cross-linked network and then increase the contact difficulty between lipase and oils. Correlation analysis revealed that C18:3n-3 was positively correlated with hardness and G' while C18:2n-6 was negative. Thus, the effect on the reduced extent of lipolysis with abundant C18:3n-3 was most significant while that rich in C18:2n-6 was least. These discoveries provided a deepening insight into DSG-based oleogels with various unsaturated fatty acids to design desirable properties.

Role of the polyphenol content on the structuring behavior of liposoluble gelators in extra virgin olive oil

The role of polyphenols in affecting the structural and rheological properties of oleogels was investigated. Polyphenols were selectively removed from extra virgin olive oil (EVOO), and the resulting oils at three different polyphenol levels were gelled by using 10% (w/w) of monoglycerides (MG), rice wax (RW), sunflower wax (SW), and a mixture of β-sitosterol/γ-oryzanol (PS). The structural characteristics of oleogels were assessed by visual appearance, rheology, polarized light microscopy, calorimetry, XRD, and FTIR. Polyphenol content differently affected oleogel characteristics depending on network features. While EVOO-polyphenols did not influence PS- and SW-based oleogels, they reinforced MG- and RW-based oleogel network. As polyphenol content increased, the critical stress and melting temperature also increased, concomitantly with changes in crystal morphology. This was attributed to the capacity of polyphenols to form additional junction points in the crystalline network.

Surfactant-free oleogel-based emulsion stabilized by co-assembled ceramide/lecithin crystals with controlled digestibility

BACKGROUND

There is increasing interest in the development of oleogel-based emulsions. However, they usually contained surfactants for stabilization, especially small-molecular weight surfactants, which may have adverse health impacts.

RESULTS

Herein, a surfactant-free oleogel-based emulsion stabilized by co-assembled ceramide/lecithin (CER/LEC) crystals was developed. The formation and stabilization mechanisms were explored. The different molar ratios of gelator (LEC and CER) in emulsions resulted in different crystal morphology, crystallinity as well as different emulsion properties. This suggested that appropriate crystallinity, crystal size, and interfacial distribution of these crystals provided higher surface coverage against droplets coalescence, thus better emulsion stabilization. Both X-ray diffractograms and contact angle results confirmed that the crystals which were primarily responsible for emulsion stabilization, are co-assembled crystals consisted of both gelators (CER and LEC). Furthermore, the percentage of free fatty acids (FFAs%) results revealed a negative relationship between lipid digestibility and crystal concentration.

CONCLUSIONS

This strategy greatly enriched surfactant-free oleogel-based emulsion formulations, as well as their potential applications in healthy lipid-based products and novel food delivery systems with controlled lipid digestibility. © 2022 Society of Chemical Industry.

The oxidative quality of bi-, oleo- and emulgels and their bioactives molecules delivery

During recent years, the applicability of bi-, oleo- and emulgels has been widely studied, proving several advantages as compared to conventional fats, such as increasing the unsaturated fat content of products and being more sustainable for temperate regions as compared to tropical fats. Moreover, these alternative fat systems improve the nutritional profile, increase the bioavailability of bioactive compounds, and can be used as preservation films and markers for the inactivation of pathogens, while in 3D printing facilitate the obtaining of superior food products. Furthermore, bi-, oleo- and emulgels offer food industries efficient, innovative, and sustainable alternatives to animal fats, shortenings, margarine, palm and coconut oil due to the nutritional improvements. According to recent studies, gels can be used as ingredients for the total or partial replacement of saturated and trans fats in the meat, bakery and pastry industry. The evaluation of the oxidative quality of this gelled systems is significant because the production process involves the use of heat treatments and continuous stirring where large amounts of air can be incorporated. The aim of this literature review is to provide a synthesis of studies to better understand the interaction of components and to identify future improvements that can be applied in oil gelling technology. Generally, higher temperatures used in obtaining polymeric gels, lead to more oxidation compounds, while a higher concentration of structuring agents leads to a better protection against oxidation. Due to the gel network ability to function as a barrier against oxidation factors, gelled matrices are able to provide superior protection for the bioactive compounds. The release percentage of bioactive molecules can be regulated by formulating the gel matrix (type and concentration of structuring agents and type of oil). In terms of food products, future research may include the use of antioxidants to improve the oxidative stability of the reformulated products.

Targeted delivery of food functional ingredients in precise nutrition: design strategy and application of nutritional intervention

With the high incidence of chronic diseases, precise nutrition is a safe and efficient nutritional intervention method to improve human health. Food functional ingredients are an important material base for precision nutrition, which have been researched for their application in preventing diseases and improving health. However, their poor solubility, stability, and bad absorption largely limit their effect on nutritional intervention. The establishment of a stable targeted delivery system is helpful to enhance their bioavailability, realize the controlled release of functional ingredients at the targeted action sites in vivo, and provide nutritional intervention approaches and methods for precise nutrition. In this review, we summarized recent studies about the types of targeted delivery systems for the delivery of functional ingredients and their digestion fate in the gastrointestinal tract, including emulsion-based delivery systems and polymer-based delivery systems. The building materials, structure, size and charge of the particles in these delivery systems were manipulated to fabricate targeted carriers. Finally, the targeted delivery systems for food functional ingredients have gained some achievements in nutritional intervention for inflammatory bowel disease (IBD), liver disease, obesity, and cancer. These findings will help in designing fine targeted delivery systems, and achieving precise nutritional intervention for food functional ingredients on human health.

Protective effect of surfactant modified phytosterol oleogels on loaded curcumin

BACKGROUND

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

RESULTS

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

CONCLUSION

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

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.

Updated design strategies for oral delivery systems: maximized bioefficacy of dietary bioactive compounds achieved by inducing proper digestive fate and sensory attributes

Interest in the application of dietary bioactive compounds (DBC) in healthcare and pharmaceutical industries has motivated researchers to develop functional delivery systems (FDS) aiming to maximize their bioefficacy. As the direct and indirect health benefiting effects of DBC are acknowledged, traditional design principle of FDS aiming at improving the bioavailability of intact DBC is challenged by the updated one, where the maximized bioefficacy of DBC delivered by FDS will be achieved via rationally absorbed at target sites with proper metabolism pathways. This article briefly summarized the absorption and metabolic fates of orally digested DBC along with their direct and indirect mechanisms to perform health benefiting effects. Current strategies in designing the next generation FDS with an emphasis on their modulation effects on the distribution portion between the upper and lower digestive tract, portal vein and lymphatic absorption, human digestive and gut microbiota enzymatic mediated metabolism were highlighted. Updated research progresses of FDS in adjusting sensory attributes of food end products and inducing synergistic effects rooting from matrix materials and co-delivered cargos were also discussed. Challenges as well as future perspectives concerning the precise nutrition and the critical role of delivery systems in dietary intervention were proposed.

3D printed MCT oleogel as a co-delivery carrier for curcumin and resveratrol

Designing a suitable matrix to protect sensitive bioactive compounds is an important stage in nutraceutical development. In this study, emulsion templated medium-chain triglycerides (MCT) oleogel was developed as co-delivery carriers for synergistic nutraceuticals, curcumin, and resveratrol and to 3D print in customized shapes for personalized nutrition. To obtain the stable emulsion, gelatin and gellan gum were added such that their protein-polysaccharide interaction helps in the structuring of the oil phase. Increasing the amount of gellan gum had a positive effect on stabilizing the emulsion but became the critical parameter during 3D printing. Hence, gellan gum of 1.5% (w/v) and gelatin at 10% (w/v) of water were considered optimum to produce a stable 30% O/W emulsion for 3D printing. Upon analyzing the in-vitro digestion behavior of the oleogel, it was observed that the bioactives were protected under oral and gastric conditions and allowed intestinal targeted delivery. The total bioaccessible fraction increased up to 1.13-fold and 1.2-fold for curcumin and resveratrol respectively compared to control (MCT oil). The FFAs release profile also indicated that gelators play an important role in lipase activity. Also, the ex-vivo everted gut sac analysis showed enhanced permeation of about 1.83 times and 1.13 times for curcumin and resveratrol respectively. Thus, this study provides useful insights into the 3D printing of emulsion templated oleogel as personalized nutraceutical carriers.

Soy oil and SPI based-oleogels structuring with glycerol monolaurate by emulsion-templated approach: Preparation, characterization and potential application

In this study, soybean oil-based oleogels were prepared using soy-protein isolate (SPI) and glycerol monolaurate (GML) in an emulsion-template approach. The rheological, texture, microstructure, and oil-retention properties of the obtained oleogels were analyzed. Results showed that the soy oil-based oleogel prepared with 6 wt% GML exhibited high oil loss, low-hardness, and needle-like morphology compared to the soy-oil/SPI-based oleogel. On the other hand, soy oil-based /SPI-based oleogels structured by 3 or 6 wt% GML presented moderate thermal-stability and lowest oil loss than those prepared without GML. Furthermore, SPI-based oleogel containing 6 wt% GML showed highest free fatty acids release (62.07%) with significantly improved elastic modulus and apparent viscosity. Additionally, the obtained oleogels displayed the occurrence of van der Waals interactions and intermolecular hydrogen bonds, presenting enhanced thermal stability. These results contribute to a better understanding of oleogelation-based emulsions for formulating trans-free and low-saturated foodstuffs with desired physical and functional properties.

Designing food for the elderly: the critical impact of food structure

Ageing is an unavoidable progressive process causing many changes of the individual life. However, if faced in an efficient way, living longer in a healthy status could be an opportunity for all. In this context, food consumption and dietary patterns are pivotal factors in promoting active and healthy ageing. The development of food products tailored for the specific needs of the elderly might favour the fulfilment of nutritionally balanced diets, while reducing the consequences of malnutrition. To this aim, the application of a food structure design approach could be particularly profitable, being food structure responsible to the final functionalities of food products. In this narrative review, the physiological changes associated to food consumption occurring during ageing were firstly discussed. Then, the focus shifted to the possible role of food structure in delivering target functionalities, considering food acceptability, digestion of the nutrients, bioactive molecules and probiotic bacteria.

Observation of curcumin-loaded hydroxypropyl methylcellulose (HPMC) oleogels under in vitro lipid digestion and in situ intestinal absorption in rats

Curcumin-loaded nanostructured lipid carriers (Cur-NLCs)-based hydroxypropyl methylcellulose (HPMC) oleogels (Cur-NLCs-HPMC-OGs) were fabricated using a cryogel template. The effect of the HPMC viscosity grade on the oleogel characteristics and in situ intestinal absorption were examined. Highly stable Cur-NLCs were prepared with a mean particle size of 314 nm and polydispersity index of 0.275. Cur-NLCs affected the creamy texture of self-standing Cur-NLCs-HPMC-OGs. The Cur-NLCs were tightly packed as oil droplets in the network of HPMC. However, a high viscosity of HPMC-4000 led to a greater ability to entrap and prevent droplet coalescence compared to a low viscosity of HPMC-400. NLCs promoted the release of free fatty acids during in vitro lipid digestion, whereas HPMC-4000 maintained the strength and durability of oleogels against mechanical and enzymatic breakdown. The in situ loop results revealed higher curcumin absorption by Cur-NLCs-HPMC-OGs than by Cur-HPMC-OGs. HMPC-4000 showed slightly higher curcumin absorption compared to HPMC-400.

The role of nanostructured lipid carriers and type of biopolymers on the lipid digestion and release rate of curcumin from curcumin-loaded oleogels

Curcumin-nanostructured lipid carrier-loaded oleogels (Cur-NLC-OGs) have been developed with biopolymer cryogels as an efficient delivery system to overcome the extremely low water solubility and instability of curcumin. The effect of NLC and biopolymer types on the encapsulation and release of curcumin from Cur-OGs was investigated. Alginate, carboxymethyl cellulose (CMC), and pectin solutions were firstly freeze dried to make biopolymer cryogels and they were mixed with Cur and Cur-NLC to obtain stable and self-standing Cur-OGs and Cur-NLC-OGs, respectively. As compared to Cur-OGs, Cur-NLC-OGs had higher encapsulation efficiency and showed slower release of curcumin under acidic condition. Although Cur-NLC affected the rapid release of free fatty acids, the Cur-NLC-OGs prepared with CMC cryogel was most efficient in delaying lipid digestion. Overall, NLC and CMC-based OGs could be effectively used to improve encapsulation efficiency and control lipolysis of lipid droplets. These results will be advantageous for the development of oleogels with desirable functionality.

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.

Oleogelation of extra virgin olive oil by different oleogelators affects the physical properties and the stability of bioactive compounds

Extra virgin olive oil (EVOO) was gelled with 10% monoglycerides, (MG), rice wax (RW), γ-oryzanol, and β-sitosterol (PS), or ethylcellulose (EC). The oleogel structure and the stability of bioactive compounds were investigated during storage up to 120 days at 20, 30, and 40 °C. All samples were self-standing but presented different structures. PS produced the firmest gel, whereas EC caused the lowest firmness and rheological values. Structural properties did not change during storage, except for EC oleogel. Structuring triggered a depletion in phenolic content and α-tocopherol, which was more pronounced when a higher temperature was required for oleogel preparation (MG ~ RW < PS < EC). However, during storage phenolics and α-tocopherol decreased following zero-order kinetics with a higher susceptibility in unstructured oil, suggesting in all cases a protective effect of the gel network.

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.