The effect of citral loading and fatty acid distribution on the oleogels: Physicochemical properties and in vitro digestion

Oleogels containing bioactive substances such as citral (CT) are used as functional food ingredients. However, little information is available on the influence of different oleogel network structure caused by CT addition and fatty acid distribution on its digestion behavior. Coconut oil, palm oil, high oleic peanut oil, safflower seed oil, and perilla seed oil were used in this study. The results showed that perilla seed oil-CT-based oleogels had the highest oil-holding capacity (99.03 ± 0.3), whereas CT addition higher than 10 wt% could lead to the morphology collapse of oleogels. Physical and thermodynamic analyses revealed that CT could reduce oleogel hardness and higher unsaturated fatty acid content is more likely to form oleogel with stable and tight crystalline network. Moreover, the dense structure of oleogels hinders the contact between oleogels and lipase, thus weakening triglyceride digestion. These findings provide valuable insights into the design of oleogels loading with CT.

Influence of oleogel composition on lipid digestibility and β-carotene bioaccessibility during in vitro digestion

This study explored how co-oleogelator type, concentration, and water addition affect lipid digestion and β-carotene (βC) bioaccessibility in corn oil oleogels. Oleogels containing 0.1% βC, 20% glyceryl stearate (GS), with lecithin (L) or hydrogenated lecithin (HL) (at 0, 0.5, or 2.5%) and their water-filled counterparts (1% water) were examined. In vitro intestinal digestion revealed HL-oleogels experienced higher lipolysis due to their smaller crystal size enhancing surface area for lipase action, whereas L-oleogels presented lower digestibility, attributed to larger oil droplets and a minimized surface area. Water addition didn't significantly change lipid digestibility. βC bioaccessibility was inversely related to co-oleogelator concentration, with L-oleogels demonstrating the largest decrease, likely due to less free fatty acids released for micelle formation. However, water-filled oleogels enhanced βC bioaccessibility. These findings highlight that tailored microstructure in oleogels can control lipid digestion and βC bioaccessibility, paving the way for designing efficient delivery systems for targeted nutrient delivery.

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.

Toward Diverse Plant Proteins for Food Innovation

This review highlights the development of plant proteins from a wide variety of sources, as most of the research and development efforts to date have been limited to a few sources including soy, chickpea, wheat, and pea. The native structure of plant proteins during production and their impact on food colloids including emulsions, foams, and gels are considered in relation to their fundamental properties, while highlighting the recent developments in the production and processing technologies with regard to their impacts on the molecular properties and aggregation of the proteins. The ability to quantify structural, morphological, and rheological properties can provide a better understanding of the roles of plant proteins in food systems. The applications of plant proteins as dairy and meat alternatives are discussed from the perspective of food structure formation. Future directions on the processing of plant proteins and potential applications are outlined to encourage the generation of more diverse plant-based products.

Effect of aluminium oxide nanoparticles on long-acting oleogels laden with Sc-PLA-chitosan nanoparticles for anti-HIV therapy

The development of a long-acting injectable drug delivery systems (DDS) of active pharmaceutical ingredients (API) holds great promise in addressing the challenges of treatment adherence, predominantly in HIV/AIDS. Polymers are inevitable carriers for the preparation of DDS, which are typically composed of polylactide (PLA), carbohydrates such as chitosan or cellulose derivatives. In this study, the tenofovir alafenamide (TAF) laden PLA-stereocomplex-chitosan nanoparticles (Sc-PLA-chitosan NPs) were developed through the spray-dried technique. These NPs had a mean particle size of 91 ± 8 nm and were incorporated into oleogels consisting of sesame oil and ethyl-cellulose. To enhance the syringeability of highly viscous oleogels, the commercially available aluminium oxide NPs were added with a size of 78 nm. The proposed DDS exhibits prolonged sustained release for up to 12 days in phosphate buffer pH 7.4. Noteworthy, the oleogels with Sc-PLA-chitosan NPs displayed extended tissue permeation properties indicating their potential long-acting in-vivo drug release. Collectively, this study recommends that the development of Sc-PLA-chitosan NPs-loaded oleogels represents a certainly adaptable long-acting injectables system for the delivery of APIs in the context of HIV/AIDS. This system is expected to contribute to improved and effective treatment adherence among patients infected with HIV and provide requisite therapeutic outcomes.

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

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

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.

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.

Edible polysaccharide-based oleogels and novel emulsion gels as fat analogues: A review

Polysaccharide-based oleogels and emulsion gels have become novel strategies to replace solid fats due to safe and plentiful raw material, healthier fatty acid composition, controllable viscoelasticity, and more varied nutrition/flavor embedding. Recently, various oleogelation techniques and novel emulsion gels have been reported further to enrich the potential of polysaccharides in oil structuring, in which a crucial step is to promote the formation of polysaccharide networks determining gel properties through different media. Meanwhile, polysaccharide-based oleogels and emulsion gels have good oil holding, nutrient/flavor embedding, and 3D food printability, and their applications as fat substitutes have been explored in foods. This paper comprehensively reviews the types, preparation methods, and mechanisms of various polysaccharide-based oleogels and emulsion gels; meanwhile, the food applications and new trends of polysaccharide-based gels are discussed. Moreover, some viewpoints about potential developments and application challenges of polysaccharide-based gels are mentioned. In the future, polysaccharide-based gels may be flexible materials for customized nutritional foods and molecular gastronomy. However, it is still a challenge to select the appropriate oleogels or emulsion gels to meet the requirements of the products. Once this issue is addressed, oleogels and emulsion gels are anticipated to be used widely.

Changing Despicable Me: Potential replacement of azo dye yellow tartrazine for pequi carotenoids employing ionic liquids as high-performance extractors

Color is a crucial sensory attribute that guides consumer expectations. A high-performance pequi carotenoid extraction process was developed using ionic liquid-based ethanolic solutions and a factorial design strategy to search for a potential substitute for the artificial azo dye yellow tartrazine. All-trans-antheraxanthin was identified with HPLC-PAD-MSn for the first time in pequi samples. [BMIM][BF4] was the most efficient ionic liquid, and the maximization process condition was the solid-liquid ratio R(S/L) of 1:3, the co-solvent ratio R(IL/E) of 1:1 ([BMIM][BF4]: ethanol), and three cycles of extraction with 300 s each and yielded 107.90 μg carotenoids/g of dry matter. The ionic liquid-ethanolic solution recyclability was accomplished by freezing and precipitating with an average recovery of 79 %. In CIELAB parameters, pequi carotenoid extracted with [BMIM][BF4] was brighter and yellower than the artificial azo dye yellow tartrazine. A color change of 11.08 and a hue* difference of 1.26° were obtained. Furthermore, carotenoids extracted with [BMIM][BF4] showed antioxidant activity of 35.84 μmol of α-tocopherol. These findings suggest the potential of employing the pequi carotenoids to replace the artificial azo dye yellow tartrazine in foods for improved functional properties.

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.

Atomic Force Microscopy of Phytosterol Based Edible Oleogels

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

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.

A bigel based formulation protects lutein better in the gastric environment with controlled release and antioxidant profile than other gel based systems

Gel based formulations offer an opportunity to fortify bioactives in food. However, a comparative evaluation of gel systems is scantly available. Thus, this study intended to evaluate the impact of various gel formulations (hydrogel, oleogel, emulsion gel, bigels of different compositions) on the delivery and antioxidant activity of lutein. Ethyl cellulose (EC,15 %w/w) and guar-xanthan gum mixture (1:1,1.5 %w/w) was used as oleogelator and hydrogelator, respectively. The microscopic evaluation indicated an oil-based continuous-phase for bigel with 75% oleogel. An increase in oleogel content enhanced textural and rheological properties. An increase in hydrogel composition (25%-75%) of bigel improved the lutein release (70.4%-83.2%). The highest release of lutein was recorded for emulsion gel (84.9%) and bigel with 25% oleogel (83.2%). The antioxidant activity was comparatively lower in gastric medium than simulated intestinal fluid. It could be inferred that the gel matrix significantly affected the lutein release, antioxidant profile, physiochemical and mechanical characteristics.

Structural modification of zein-based oil-in-glycerol emulsion gels for improved textural and digestion behaviors

Zein can dissolve in glycerol, and can be developed into oil-in-glycerol emulsion gels to widen its applications. The current study focused on modulating the structures of zein-based emulsion gels by the addition of a surface active ingredient (Span 20, SP) to improve textural and digestion behaviors. Microstructural observation indicated that the addition of SP replaced zein from the oil-glycerol interface, and allowed a higher level of oil droplet aggregation. After adding SP, the gel hardness decreased from 3.43 ± 0.14 N to 1.62 ± 0.01 N, and the storage modulus also decreased with the increase of SP content. Viscoelasticity of the gels was thermo-responsive, and the presence of SP contributed to a higher recovery of the storage modulus after the heating-cooling process. The addition of SP reduced the oil-binding capacity of zein gel from 97.61 ± 0.19% to 82.00 ± 0.92% and the solvent-binding capacity from 75.97 ± 3.05% to 62.25 ± 0.22%, indicating that the zein network was weakened. Then, gels were mixed with simulated digestive juices to track the changes of gel structures and the release of free fatty acids. The addition of SP accelerated the digestion process, especially intestinal digestion. SP contributed to a higher fluorescence intensity in the digesta, which was a sign of a higher level of digestion of zein. Subsequently, the addition of SP increased the release content of free fatty acids from 4.27 ± 0.71% to 5.07 ± 1.27%. The above findings would be useful in designing zein-based functional food products with favored textural and digestion properties.

Engineering effect of oleogels with different structuring mechanisms on the crystallization behavior of cocoa butter

As promising cocoa butter (CB) alternatives, oleogels have the potential to prevent fat blooms of chocolate. We aimed to explore possible reasons for the bloom resistance of oleogels by investigating the crystallization behavior of CB-oleogel blends, including crystallization kinetics, thermodynamic properties, crystal polymorphism, and oil distribution. Oleogels structured by monoglyceric stearate (MO), β-sitosterol/lecithin (SLO), and ethylcellulose (EO) were selected as representative oleogels with various structuring-mechanisms. Crystallization kinetic results showed that the crystallization dimension of CB-oleogel increased with the oleogel proportion (from one-dimensional to multi-dimensional), confirming that CB crystallization was inhibited. The presence of liquid oil and oleogelators in oleogels may increase the free energy barrier for CB crystallization. The proton mobility of liquid oil in CB-MO was lower because MO was more tightly bound to CB. The crystallization mechanism of the CB-oleogel suggested that the inhibitory effect of oleogels on CB crystallization delayed the polymorphic transition, thereby improving the bloom stability of chocolate.

Effects of polysaccharide thickening agent on the preparation of walnut oil oleogels based on methylcellulose: Characterization and delivery of curcumin

Walnut oil-based oleogels were prepared by the emulsion-templated method using methylcellulose at different concentrations and viscosities as the oleogelators and polysaccharides (sodium alginate, xanthan gum and κ-carrageenan) as the thickening agents. The microscopic properties, rheological properties and oil binding capacity (OBC) of the oleogels were evaluated. The intermolecular and intramolecular hydrogen bonding of polysaccharide stabilized the network structure of the oleogel. The increasing methylcellulose concentration contributed to forming a more stable interfacial layer and providing oleogel with a compact structure. κ-Carrageenan resulted in a better OBC (97.37 %) and rheological properties of the methylcellulose-based oleogel. When served as a delivery system of curcumin, the highest encapsulation rate of curcumin (38.06 %) was achieved by the κ-carrageenan oleogel. The structure of oleogels slowed down the release rate of free fatty acids and curcumin during the early stage of in vitro digestion and the κ-carrageenan oleogel exhibited the highest inhibiting effect. This finding suggests that the polysaccharide-based walnut oil oleogels had a firmer structure and could be a promising approach to deliver curcumin.

Cold pressed pumpkin seed oil fatty acids, carotenoids, volatile compounds profiles and infrared fingerprints as affected by storage time and wax-based oleogelation

BACKGROUND

Pumpkin seed and sunflower oil are rich in bioactive compounds, but are prone to oxidation during storage. Their fatty acids, carotenoid and volatile compounds and their Fourier-transform infrared (FTIR) profiles were studied during 8 months storage in order to assess the overall quality, but also to assess the impact of the oleogelation as conditioning process.

RESULTS

The fatty acids methyl esters were analyzed by gas chromatography-mass spectrometry (GC-MS). The linoleic acid was the most abundant in the oils (604.6 g kg^-1 in pumpkin and 690 g kg^-1 in sunflower), but also in oleogels. Through high-performance liquid chromatography (HPLC), lutein and β-carotene were determined as specific carotenoid compounds of the pumpkin seed oil and oleogel, in a total amount of 0.0072 g kg^-1 . The volatile compounds profile revealed the presence of alpha-pinene for the pumpkin seed oil and oleogels and a tentative identification of limonene for the sunflower oil. Hexanal was also detected in the oleogels, indicating a thermal oxidation, which was further analyzed through infrared spectroscopy.

CONCLUSIONS

During 8 months storage, the decrease of polyunsaturated fatty acid total amount was 5.72% for the pumpkin seed oil and 3.55% for the oleogel, while in the sunflower oil samples of 2.93% and 3.28% for the oleogel. It was concluded that oleogelation might protect specific carotenoid compounds, since the oleogels displayed higher content of β-carotene at each storage time. Hexanal and heptanal were detected during storage, regardless of the oil or oleogel type. FTIR analysis depicts the differences in the constituent fatty acids resulting due to thermal oxidation or due to storage. © 2022 Society of Chemical Industry.

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.

Nanocellulose incorporated oleogel matrix for controlled-release of active ingredients in the lower gastrointestinal tract

Controlled release is often preferred for orally administrated bioactive compounds and drugs. In this study, a nanocellulose (NC) incorporated oleogel encapsulation system was developed for controlled release of active agents. 5-Aminosalicylic acid (5-ASA), an anti-inflammatory drug to treat inflammatory bowel diseases, was used as an example core ingredient for demonstrating the efficacy of the system. Oleogels with/without NC incorporation encapsulating 5-ASA were prepared and tested by in vitro digestion study, and 5-ASA released from the matrix was quantified by a novel UV-Vis spectrometric method developed in this study. The oleogel encapsulation system was characterized by assessing the encapsulation efficiency, oxidative stability, gel hardness, microstructure, and thermal stability. Results showed that sorbitan tristearate-induced oleogel system successfully protected 5-ASA during GI digestion. The incorporation of NC solutions with different NC types, concentrations and volumes further modified the release rate. Specifically, the release of 5-ASA in NC incorporated matrix was <6 % in the gastric phase, and ranged between 17.42 % - 38.28 % in the small intestine depending on the added NC type and concentration. Additionally, the incorporation of NC improved physicochemical stability of the gel matrix. The new 5-ASA quantification method developed in this study is simpler and faster compared with currently available methods.

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.

Evaluation of Pure Bile Salts in Place of Bile Extract in the Standardized INFOGEST Digestion Protocol for Quantification of Sterol Bioaccessibility

Improving standardized in vitro digestion protocols for phytosterols (PSs) is critical for understanding their bioaccessibility (BA) in food products and supplements. In this study, in vitro BA of phytosterol esters (PSEs) and free cholesterol (Ch) was compared under modified digestion conditions. The addition of Ch esterase (CE) to the INFOGEST model containing bovine bile resulted in a 70% increase in PS BA and an 18.5% reduction in Ch micellarization. Relative to the standardized INFOGEST model, substitution of pure bile salts (PBSs) did not significantly change PS BA or Ch micellarization. In the presence of CE, the substitution resulted in a 49.9% reduction in PS BA and a 13% increase in Ch micellarization. The differing results may be due to inhibitory effects of PBSs on the activity of intestinal enzymes, including CE. These results suggest that the INFOGEST model should include Ch esterase and the continued use of bile extract to evaluate PS BA.

Fibrous and Spherical Aggregates of Ovotransferrin as Stabilizers for Oleogel-Based Pickering Emulsions: Preparation, Characteristics and Curcumin Delivery

This study aimed to explore the effects and mechanisms of differently shaped aggregates of ovotransferrin (OVT) particles on oleogel-based Pickering emulsions (OPEs). Medium-chain triglyceride oil-based oleogels were constructed using beeswax, and their gel-sol melting temperatures were investigated. Atomic force microscopy confirmed that both OVT fibrils and OVT spheres were successfully prepared, and the three-phase contact angle measurements indicated that fibrous and spherical aggregates of OVT particles possessed great potential to stabilize the OPEs. Afterward, the oil-in-water OPEs were fabricated using oleogel as the oil phase and OVT fibrils/spheres as the emulsifiers. The results revealed that OPEs stabilized with OVT fibrils (FIB-OPEs) presented a higher degree of emulsification, smaller droplet size, better physical stability and stronger apparent viscosity compared with OPEs stabilized with OVT spheres (SPH-OPEs). The freeze–thaw stability test showed that the FIB-OPEs remained stable after three freeze–thaw cycles, while the SPH-OPEs could barely withstand one freeze–thaw cycle. An in vitro digestion study suggested that OVT fibrils conferred distinctly higher lipolysis (46.0%) and bioaccessibility (62.8%) of curcumin to OPEs.

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.

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.

Development of oil-based gels as versatile drug delivery systems for pediatric applications

Administering medicines to 0- to 5-year-old children in a resource-limited environment requires dosage forms that circumvent swallowing solids, avoid on-field reconstitution, and are thermostable, cheap, versatile, and taste masking. We present a strategy that stands to solve this multifaceted problem. As many drugs lack adequate water solubility, our formulations used oils, whose textures could be modified with gelling agents to form "oleogels." In a clinical study, we showed that the oleogels can be formulated to be as fluid as thickened beverages and as stiff as yogurt puddings. In swine, oleogels could deliver four drugs ranging three orders of magnitude in their water solubilities and two orders of magnitude in their partition coefficients. Oleogels could be stabilized at 40°C for prolonged durations and used without redispersion. Last, we developed a macrofluidic system enabling fixed and metered dosing. We anticipate that this platform could be adopted for pediatric dosing, palliative care, and gastrointestinal disease applications.

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.

Oil-Based Delivery Control Release System Targeted to the Later Part of the Gastrointestinal Tract-A Mechanistic Study

Oil-based drug delivery systems have been studied in different aspects. The present study proposes a new application for an oil-based delivery system, focusing on controlled release until the drug reaches the later part of the small intestine. Bulk surfactants and interfacial surfactants were added into the oil formulation to provide a better mechanistic understating of the lipolysis. Validation of the modified in vitro method shows the overall conversion from medium-chain triglyceride oil (MCT oil) to free fatty acids (FFA) of 100 ± 4% in five replicates. This fully converted level and high reproducibility are fundamental for the following investigations where any retarding effect can be distinguished from the experimental errors. The results show that viscosity and thermodynamic activity have limited retardation. Furthermore, the former may change the kinetics of lipolysis, while the latter changes the equilibrium level. The gel-forming retarder (ethylcellulose) displayed a strong effect. Whereas the lipolysis was significantly retarded (>50%) when the retarders altered the interfacial composition (poloxamer 407), degradable interfacial surfactants did not have the same effect. However, surface-active, lipolysis-resistant retarders with a high CMC did not show a retarding effect.

Synergetic effects of water-soluble polysaccharides for intensifying performances of oleogels fabricated by oil-absorbing cryogels

Oleogels were prepared by the cryogel-templated method from porous cryogels, which were co-structured using hydroxypropyl-methylcellulose and structural enhancers (such as flaxseed gum, κ-carrageenan, carboxymethyl-cellulose, arabic gum, and guar gum). The hardness, network density, pore size, pore volume, and SEM micrographs of cryogels showed that κ-carrageenan and flaxseed gum could keep the integrity of aqueous foams during freeze-drying and endow cryogels with the high hardness and content to hold oils (>98%). Oil absorption curves indicated that flaxseed gum and guar gum-enhanced cryogels provided the fastest oil absorption rate due to bigger pores. The absorption model was fitted well with all experimental data. Physical and mechanical properties of cryogels were positively related to the rheological property and oil bonding capacity of oleogels. κ-carrageenan and flaxseed gum were more suitable as structural enhancers to improve hydroxypropyl-methylcellulose-based cryogels for preparing oleogels to replace plastic fats in foods.

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.

Multicompartment Hydrogels

Hydrogels belong to the most promising materials in polymer and materials science at the moment. As they feature soft and tissue-like character as well as high water-content, a broad range of applications are addressed with hydrogels, e.g. tissue engineering and wound dressings but also soft robotics, drug delivery, actuators and catalysis. Ways to tailor hydrogel properties are crosslinking mechanism, hydrogel shape and reinforcement, but new features can be introduced by variation of hydrogel composition as well, e.g. via monomer choice, functionalization or compartmentalization. Especially, multicompartment hydrogels drive progress towards complex and highly functional soft materials. In the present review the latest developments in multicompartment hydrogels are highlighted with a focus on three types of compartments, i.e. micellar/vesicular, droplets or multi-layers including various sub-categories. Furthermore, several morphologies of compartmentalized hydrogels and applications of multicompartment hydrogels will be discussed as well. Finally, an outlook towards future developments of the field will be given. The further development of multicompartment hydrogels is highly relevant for a broad range of applications and will have a significant impact on biomedicine and organic devices. This article is protected by copyright. All rights reserved.

Monoglyceride oleogels for lipophilic bioactive delivery - Influence of self-assembled structures on stability and in vitro bioaccessibility of astaxanthin

The present study investigated the influence of self-assembled structures on stability and in vitro bioaccessibility of astaxanthin by modifying the structures with different processing conditions. The self-assembled structures of GMS oleogels were changed to produce smaller crystals and more compact network at higher glycerol monostearate (GMS) concentration and lower cooling temperature, resulting in higher hardness, oil binding capacity, and viscoelastic properties of oleogels. In the stability test, the highest retention ratio of astaxanthin was observed in oleogels formed at 4 °C and 10% GMS, indicating that the denser network structures were more effective to prevent the degradation of astaxanthin. During in vitro digestion, the self-assembled structures of oleogels and the nature of GMS molecules affected the lipolysis and micellization, which in turn regulated the bioaccessibility of astaxanthin. Collectively, GMS oleogels were effective delivery materials for improving the stability and bioaccessibility of lipophilic bioactives.

Development of Antioxidant-Fortified Oleogel and Its Application as a Solid Fat Replacer to Muffin

Oleogelation has recently received a great deal of attention in the food industry as a novel alternative technology that physically converts liquid oil into semi-solid gel. Since the functional characteristics of oleogels are dependent on the gelators or bioactive compounds incorporated, this study was undertaken to evaluate the rheological properties and oxidative stability of candelilla wax oleogels fortified with glycerol monostearate (GMS) and β-carotene, and also to investigate their applications to muffin as a shortening replacer. The interaction between candelilla wax and GMS contributed to strengthening the oleogel structure. The oleogels with β-carotene showed the lowest peroxide values than the other samples. The muffins prepared with oleogels for shortening had greater specific gravity and harder texture, but there was no significant difference in the specific volume between the shortening and oleogel samples with GMS. In addition, muffins with β-carotene oleogels showed the highest oxidative stability. Therefore, this study indicated that the incorporation of β-carotene and GMS in oleogels positively affected the storage stability of muffin.

Effect of operating parameters on the physical and chemical stability of an oil gelled-in-water emulsified curcumin delivery system

BACKGROUND

Curcumin is a natural antioxidant with important beneficial properties for health, although its low bioavailability and sensitivity to many environmental agents limits its use in the food industry. Furthermore, some studies mention a potential synergistic effect with omega-3 polyunsaturated fatty acids, comprising other bioactive compounds extremely unstable and susceptible to oxidation. A relatively novel strategy to avoid oxidation processes is to transform liquid oils into three-dimensional structures by adding a gelling agent and forming a self-assembled network that can later be vectorized by incorporating it into other systems. The present study aimed to design and optimize an oil gelled-in-water curcumin-loaded emulsion to maximize curcumin stability and minimize lipid oxidation in terms of some critical operating parameters, such as dispersed phase, emulsifier and stabilizer concentrations, and homogenization rate.

RESULTS

The operating conditions that had a significant effect on the formulation were the dispersed phase weight fraction affecting droplet size and total lipid oxidation, homogenization conditions affecting droplet size and primary lipid oxidation, and emulsifier concentration affecting droplet size (significance level = 95%). The optimal formulation for maximizing curcumin load and minimizing lipid oxidation in the oleogelified matrix was 140.4 g kg^-1 dispersed phase, 50.0 g kg^-1 emulsifier, 4.9 g kg^-1 stabilizer and homogenization speed 1016 × g.

CONCLUSION

The results obtained in the present study provide a valuable tool for the rational design and development of oil gelled-in-water emulsions that stabilize and transport bioactive compounds such as curcumin. © 2021 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.