Investigation of the fabrication, characterization, protective effect and digestive mechanism of a novel Pickering emulsion gels

Fabrication and characterization of algal oil-loaded Pickering emulsion gels stabilized by whey protein isolate/starch complex as an emergency food

Pickering emulsion gels (PEGs) as emergency food have garnered significant attention due to encapsulate and protect bioactive compounds, ensuring prolonged stability and controlled release under harsh conditions. In this study, whey protein isolate (WPI) and starch nanocomposites (SNPs) with different WPI/SNPs ratios were formulated to stabilize PEGs for the delivery of algal oil as an emergency food. The addition of gelatinized starch enhanced the wettability of the WPI/SNPs, reaching a peak three-phase contact angle of 81.9° at a WPI/SNPs 5:8. Analysis of appearance, micromorphology, droplet size distribution, and rheological behavior confirmed the formation of stable PEGs stabilized by WPI/SNPs. The PEGs demonstrated remarkable stability, maintaining integrity at room temperature for at least 12 weeks, which is attributed to their compact three-dimensional network structure. Additionally, in vitro digestion studies revealed that the starch-based PEGs retained their form during simulated oral and gastric digestion, successfully reaching the intestine. PEGs increased blood glucose by 24.25 % within 30 min and enhanced HepG2 cell migration by 10.47 %, aiding wound healing. Despite their potential, challenges include scalability, regulatory approval, and long-term safety validation. These findings highlight PEGs' promise as nutrient-rich emergency food carriers.

Starch nanoparticles regulate the steric conformation of soy protein isolate to stabilize high internal phase Pickering emulsions for curcumin encapsulation

This study aimed to the fabrication of high internal phase Pickering emulsions (HIPEs) via regulating the complexation of starch nanoparticles (SNPs) with soy protein isolate (SPI) at the oil-water interface. The formation of SNPs-SPI complexes was driven by the electrostatic adsorption and hydrogen bond interactions, which enhanced the biphasic wettability and reduced the interfacial tension. The SNPs-SPI complexes exhibited the superior emulsifying properties compared to those of SPI, with the SNPs3-SPI achieving the highest emulsion activity index (EAI, 65.67 m2/g) and emulsion stability index (ESI, 138.48 min). The rheological measurement revealed that the HIPEs stabilized by SNPs-SPI complexes (SNPs-SPI-E) exhibited the higher viscoelastic and gel-like structure than those of HIPEs stabilized by SPI (SPI-E). The adsorption of SNPs at the oil-water interface endowed the SNPs-SPI-E with higher encapsulation efficiency of curcumin (83.19 %-92.37 %) than that of SPI-E (75.42 %), which impeded the degradation and oxidation of curcumin. Moreover, the SNPs-SPI-E possessed the excellent storage and thermal stabilities than those of SPI-E. The curcumin encapsulated in SNPs-SPI-E exhibited the increased bioaccessibility, with SNPs3-SPI-E reaching the highest value of 38.92 %. This research would be beneficial to development of SNPs-SPI complexes interface for stabilizing HIPEs and modulating the encapsulation of bioactive ingredients.

Fabrication of Rubus chingii Hu ellagitannins-loaded W/O and O/W emulsion gels: Structure, stability, in vitro digestion and in vivo metabolism

Tannin is the main naturally occurring phytochemicals in Rubus chingii Hu with poor digestive stability and low bioavailability. In this study, oil-in-water (O/W) and water-in-oil (W/O) emulsion gels encapsulating Rubus chingii Hu ellagitannins (RCHT) were fabricated and their structure, rheology, stability, in vitro digestion and in vivo metabolism were characterized. The W/O emulsion gel showed smaller particle size, better pH stability, thermal stability, centrifugal stability and storage stability. Regarding rheology, two emulsion gels exhibited characteristics of non-Newtonian fluids. The encapsulation efficiency of W/O emulsion gel was higher, reaching 95.46 %. The lower release rate and higher bioaccessibility of RCHT were also observed in the W/O emulsion gel. In vitro fermentation results indicated that W/O emulsion gel could promote the growth of intestinal beneficial bacteria and inhibit the growth of harmful bacteria. Metabolic kinetics in rats showed that the embedding of W/O emulsion gel greatly promoted the absorption and transformation of ellagitannins to urolithins in vivo. Thus, the W/O emulsion gel was quite suitable for the delivery of RCHT.

Effect of K2CO3 on konjac glucomannan/κ-carrageenan-based camellia oil Pickering emulsion gel for the development of fat analogs

Konjac glucomannan (KGM) undergoes deacetylation in alkaline conditions, while κ-carrageenan (CRG) is sensitive to potassium ions. This study examines the influence of K2CO3 on the mechanical properties of KGM/CRG-based camellia oil Pickering emulsion gels. Texture analysis and rheological testing revealed that the addition of K2CO3 significantly enhanced the mechanical properties of emulsion gels. Texture parameters, such as the hardness, gumminess, and chewiness of the gel, were closer to those of pork back fat when the K2CO3 concentration was 0.2 M. The addition of K2CO3 enhance the intermolecular crosslinking within the gel and formed a more uniform and dense gel network, promoting gelation and structural stability, which were confirmed by Fourier transform infrared spectroscopy, X-ray diffraction, and microstructural analysis. Besides, low-field nuclear magnetic resonance and thermogravimetric analyses indicated that the addition of K2CO3 reduced the water mobility of the gel and improved its thermal stability. Physicochemical and color analysis results showed that the energy value of the camellia oil Pickering emulsion gel was only 15.9 % that of pork back fat, and its appearance was closer to that of pork back fat than hydrogels. This study provides technical support for the use of KGM/CRG-based camellia oil Pickering emulsion gels as fat analogs.

Controlled lipid digestion in the development of functional and personalized foods for a tailored delivery of dietary fats

In recent decades, obesity and its associated health issues have risen dramatically. The COVID-19 pandemic has further exacerbated this trend, underscoring the pressing need for new strategies to manage weight. Functional foods designed to modulate lipid digestion and absorption rates and thereby reduce the assimilation of dietary fats have gained increasing attention in food science as a potentially safer alternative to weight-loss medications. This review provides insights into controlled lipid digestion and customized delivery of fats. The first section introduces basic concepts of lipid digestion and absorption in the human gastrointestinal tract. The second section discusses factors regulating lipid digestion and absorption rates, as well as strategies for modulating lipid assimilation from food. The third section focuses on applications of controlled lipid digestion in developing personalized foods designed for specific consumer groups, with particular emphasis on two target populations: overweight individuals and infants.

Pickering emulsion gels with curdlan as both the emulsifier and the gelling agent: Emulsifying mechanism, gelling performance and gel properties

For the first time, curdlan (CL) was reported to have emulsifying property. Based on its emulsifying property and gelling property, the CL-based simple-structured emulsion gels were prepared. Among different CLs, CL-4 showed relatively good emulsifying property and its based emulsion showed the best stability, which might be mainly due to its highest hydrophobic property. The initial CL-4 gel formation temperature of the emulsion increased with oil volume fraction, which might be due to the oil droplets' interfering effect. Many non-spherical oil droplets appeared in the emulsion gel, which was mainly due to the squeezing effect of CL-4 gelation. The hardness, chewiness, springiness and cohesiveness of CL-4 based emulsion gels increased with CL-4 content. The texture parameters of emulsion gels with oil ratio ranging from 20 % to 40 % did not change significantly, which might benefit for increasing functional components' transportation efficiency of the emulsion gel without weakening its gel property significantly.

Eryngo essential oil nanoemulsion stabilized by sonicated-insect protein isolate: An innovative edible coating for strawberry quality and shelf-life extension

New bioactive coatings with eryngo essential oil (EEO) nanoemulsions stabilized by ultrasonically-treated lesser mealworm protein isolate (LMPI) were developed to extend strawberry shelf life and quality. EEO due to high carvone (43.03 %), phenolics (87.45 mg gallic acid equivalent/g), flavonoids (13.56 mg quercetin equivalent/g), and carotenoids (635.07 mg/kg) contents exhibited a significant antioxidant activity comparable to ascorbic acid (AA) and BHT. Nanoemulsions stabilized with 9 % sonicated LMPI showed smaller droplet size, higher negative ζ-potential, and greater stability, turbidity, and encapsulation efficiency of EEO compared to those stabilized with native LMPI. The FTIR spectra showed that sonicated LMPI had structural changes enhancing its emulsifying activity, with key peaks indicating the presence of hydrogen bonds, carbonyl groups, and protein conformations in both EEO and LMPI. Strawberries coated with optimal EEO-loaded nanoemulsions showed superior quality with minimal storage-dependent physicochemical, textural, color, and sensory changes compared to control samples. This edible coating also maintained higher total monomeric anthocyanin and AA contents with lower peroxidase activity during storage than EEO-based coatings. However, no significant difference in superoxide dismutase activity between samples covered by EEO and EEO-loaded nanoemulsions over 14 days of storage was found. Bioactive nanoemulsions stabilized by insect proteins would be an eco-friendly and safe approach to upholding quality standards in stored fruits and vegetables.

Preparation and properties of β-carotene-loaded sanxan emulsion gel microcapsules

Sanxan has important application value in the field of bioactive substance delivery. However, the current sanxan emulsion gel method has certain limitations in delivering heat-sensitive lipophilic bioactive substances. In this study, the acid-gelling properties of sanxan were utilized to prepare sanxan emulsion gel microcapsules (SEGMs) by extrusion dripping method. The sanxan Pickering emulsion had a particle size of 298.4 nm and an absolute ζ-potential of 48.6 mV, exhibiting better stability. As the concentration of sanxan increased from 0.5 % to 0.9 %, the hardness of SEGMs prepared with gluconolactone as the fixing solution increased by 104.1 %. SEM results showed that oil droplets in the emulsion gels were uniformly distributed in the network of sanxan gels, resulting in smooth and dense wavy structures. Moreover, the porosity of SEGMs could be adjusted by the concentration of sanxan and the oil phase fraction jointly. The in vitro digestion simulation test indicated that SEGMs had a protective effect on β-carotene in simulated gastric fluid, with a release rate of 0.56 %. In simulated intestinal fluid, SEGMs slowly released β-carotene with a release rate of 66.20 %. The results of this study provide theoretical support for the use of sanxan-based emulsion gels or oleogels as lipophilic nutrient delivery systems.

Pickering emulsions embedded in Bletilla striata polysaccharide based nanogel for enhancing skin-whitening effect of essential oils

To improve the retention time and skin-whitening efficacy of Atractylodes macrocephale essential oil (AMO), a novel Pickering emulsion based nanogel loaded with AMO (AMO-PEG) was successfully developed. This formulation employed nano-pearl powder (NPP) as the particle stabilizer for the Pickering emulsion and Bletilla striata polysaccharide (BSP) as the gel matrix. The pH, rheological properties, hardness, and elasticity of AMO-PEG were affected by the ratio of AMO-Pickering emulsion (AMO-PE) to BSP gel matrix. The results showed that AMO-PEG exhibited solid-like behavior and was capable of forming nanogels when the ratio of AMO-PE to BSP was 1:1. AMO-PE and AMO-PEG are two different dosage forms in the preparation of AMO. The effects of varying dosage forms on AMO were evaluated by in vitro transdermal release, skin irritation test, and skin-whitening effect. AMO-PEG conforms to the zero-order kinetic equation (R2 = 0.9189). The skin retention rate of AMO-PEG was 1.37 times higher than that of AMO-PE, indicating that AMO-PEG could continuously and slowly exert the whitening effect of the drugs. Compared with AMO-PE, AMO-PEG significantly increased the inhibition of tyrosinase activity and melanogenesis in B16F10 cells. AMO-PEG can promote the inhibition of B16F10 cells and improve the whitening effect of AMO and BSP. In conclusion, the Pickering emulsion based nanogel appears to be a promising strategy for enhancing the skin-whitening efficacy of both AMO and BSP.

From theoretical aspects to practical food Pickering emulsions: Formation, stabilization, and complexities linked to the use of colloidal food particles

We noticed that in literature, the term Pickering emulsion (PE) is used as soon as ingredients contain particles, and in this review, we ask ourselves if that is done rightfully so. The basic behavior taking place in particle-stabilized emulsions leads to the conclusion that the desorption energy of particles is generally high making particles highly suited to physically stabilize emulsions. Exceptions are particles with extreme contact angles or systems with very low interfacial tension. Particles used in food and biobased applications are soft, can deform when adsorbed, and most probably have molecules extending into both phases thus increasing desorption energy. Besides, surface-active components will be present either in the ingredients or generated by the emulsification process used, which will reduce the energy of desorption, either by reduced interfacial tension, or changes in the contact angle. In this paper, we describe the relative relevance of these aspects, and how to distinguish them in practice. Practical food emulsions may derive part of their stability from the presence of particles, but most likely have mixed interfaces, and are thus not PEs. Especially when small particles are used to stabilize (sub)micrometer droplets, emulsions may become unstable upon receiving a heat treatment. Stability can be enhanced by connecting the particles or creating network that spans the product, albeit this goes beyond classical Pickering stabilization. Through the architecture of PEs, special functionalities can be created, such as reduction of lipid oxidation, and controlled release features.

Jammed Pickering Emulsion Gels

Emulsion gels with specific rheological properties have widespread applications in foods, cosmetics, and biomedicines. However, the constructions of water-in-oil emulsion gels are still challenging, due to the limited interactions available in the continuous oil phase. Here, a versatile strategy is developed to prepare a new type of emulsion gels, called Jammed Pickering emulsion gels (JPEGs). In the JPEG system, SiO2 NPs in the oil phase serve as colloidal surfactants to stabilize water-in-oil Pickering emulsions, while positively-charged NH2-PEG-NH2 molecules in the water phase cross-link negatively-charged SiO2 NPs at the water/oil interface, making NP-stabilized water droplets hard to deform and thus jamming the emulsion system to form emulsion gels. The strategy to prepare JPEGs is versatile and applicable to diverse oil phases. The designed JPEGs possess many advantages, including good biocompatibility for widespread applications, shear-thinning rheological properties for easy processing, good stability Over a wide temperature range and Against centrifugation, good adhesion to wet tissues for tissue engineering, and well-controlled sustained release Under intestinal conditions. The developed JPEGs are demonstrated to be a promising delivery platform and the strategy to achieve JPEGs will trigger more innovations of material design.

Pickering emulsion gel of polyunsaturated fatty acid-rich oils stabilized by zein-tannic acid green nanoparticles for storage and oxidation stability enhancement

HYPOTHESIS

Poor storage stability and oxidative deterioration are the common drawbacks of edible oils rich in polyunsaturated fatty acids (PUFAs). We hypothesized that the natural zein/tannic acid self-assembly nanoparticles (ZT NPs) could be employed as stabilizers to anchor at the oil-water interface, thus constructing Pickering emulsion gel (PKEG) system for three types of PUFA-rich oils, soybean oil (SO), fish oil (FO) and cod liver oil (CLO), to improve the storage and oxidation stability.

EXPERIMENTS

ZT NPs were prepared by the anti-solvent coprecipitation method, and the three-phase contact angle, FT-IR, and XRD were mainly characterized. To observe the shell-core structure and oil-water interface details of SO/FO/CLO PKEGs by confocal laser scanning microscope and cryo-scanning electron microscope. Accelerated oxidation of FO was performed to assess the protective effect of PKEG on lipids.

FINDINGS

The SO, FO, and CLO PKEGs stabilized by 2 % ZT NPs, with oil fraction (φ = 0.5-0.6), were obtained. PKEGs show high viscoelasticity, clear shell-core structure spatial network structure, and ideal storage stability. Under accelerated oxidation, the degree of oxidative rancidity of FO PKEG was obviously lower than that of free FO. Overall, this work opens up new possibilities for using natural PKEG to prevent oxidative deterioration and prolong the shelf-life of PUFA-rich oils.

Cholic Acid/Glutathione-Assembled Nanofibrils for Stabilizing Pickering Emulsion Biogels

Achieving the delicate balance required for both emulsion and gel characteristics, while also imparting biological functionality in gelled emulsions, poses a significant challenge. Herein, we report on Pickering emulsion biogels formed by novel biological nanofibrils assembled from natural glutathione (GSH) and a tripod cholic acid derivative (TCA) via electrostatic interactions. GSH, composed of tripeptides with carboxyl groups, facilitates the protonation and dissolution of TCA compounds in water and the electrostatic interactions between GSH and TCA trigger nanofibrillar assembly. Fibrous nuclei initially emerge, and the formed mature nanofibrils can generate a stable hydrogel at a low solid concentration. These nanofibrils exhibit efficient emulsifying capability, enabling the preparation of stable Pickering oil-in-water (O/W) emulsion gels with adjustable phase volume ratios. The entangled nanofibrils adsorbed at the oil-water interface restrict droplet movement, imparting viscoelasticity and injectability to the emulsions. Remarkably, the biocompatible nanofibrils and stabilized emulsion gels demonstrate promising scavenging properties against reactive oxygen species (ROS). This strategy may open new scenarios for the design of advanced emulsion gel materials using natural precursors and affordable building blocks for biomedical applications.

Effect of sodium alginate and egg white protein combinations on the functional properties and structures of chicken myofibrillar protein

This research explored the influence of varying sodium alginate (SA) and egg white protein (EWP) ratios (1:2, 2:3, 1:1, 3:2, 2:1, v/v) on the structural and gel characteristics of chicken myofibrillar protein (MP) gels. The findings showed that containing SA and EWP significantly improved (P < 0.05) the water-holding capacity (up to 95.02 %) and whiteness of MP gels. With a 2:1 ratio of SA to EWP, the absolute value of zeta potential reached 17.3 mV, and the lowest cooking loss (16.98 %) was achieved, accompanied by a reduction in turbidity. The MP formulation incorporating a 2:1 ratio of SA to EWP demonstrated the highest hardness, chewiness, cohesiveness, and springiness (P < 0.05), as confirmed by the rheological analysis conducted under temperature sweep mode. As the SA content increased, there was a notable enhancement in both the storage modulus (G') and loss modulus (G″) of MP gel, indicating a strengthened cross-linking effect within the MP protein gel. FTIR and SEM analyses revealed a transformation from α-helix to β-sheet and the formation of a more uniform and dense gel structure due to non-covalent interactions. Overall, MP incorporating SA/EWP at a 2:1 ratio (v/v) has preferable gel properties. This study could provide a theoretical reference to enhance the gel attributes of chicken meat products in the industry through the utilization of SA and EWP.

Impact of κ-Carrageenan on the Freshwater Mussel (Solenaia oleivora) Protein Emulsion Gels: Gel Formation, Stability, and Curcumin Delivery

Protein-based emulsion gels are an ideal delivery system due to their unique structure, remarkable encapsulation efficiency, and tunable digestive behavior. Freshwater mussel (Solenaia oleivora) protein isolate (SoPI), an emerging sustainable protein with high nutritional value, possesses unique value in the development of functional foods. Herein, composite emulsion gels were fabricated with SoPI and κ-carrageenan (κ-CG) for the delivery of curcumin. SoPI/κ-CG stabilized emulsions possessed a high encapsulation efficiency of curcumin with a value of around 95%. The addition of κ-CG above 0.50% facilitated the emulsion gel formation and significantly improved the gel strength with 1326 g. Furthermore, the storage and digestive stability of curcumin were significantly improved as the κ-CG concentration increased. At 1.50% κ-CG, around 80% and 90% curcumin remained after 21-day storage at 45 °C and the 6 h in vitro gastrointestinal digestion, respectively. The addition of 0.50% κ-CG obtained the highest bioaccessibility of curcumin (~60%). This study illustrated the potential of SoPI emulsion gels as a carrier for stabilizing and delivering hydrophobic polyphenols.

The structural, antioxidant and emulsifying properties of cellulose nanofiber-dihydromyricetin mixtures: Effects of composite ratio

In this work, effects of cellulose nanofiber/dihydromyricetin (CNF/DMY) ratio on the structural, antioxidant and emulsifying properties of the CNF/DMY mixtures were investigated. CNF integrated with DMY via hydrogen bonding and the antioxidant capacity of mixtures increased with decreasing CNF/DMY ratio (k). The oxidative stability of emulsions enhanced as the DMY content increased. Emulsions formed at Φ = 0.5 displayed larger size (about 25 μm), better viscoelasticity and centrifugal stability than those at Φ = 0.3 (about 23 μm). The emulsions at k = 17:3 and Φ = 0.5 exhibited the most excellent viscoelasticity. In conclusion, the DMY content in mixtures and the oil phase fraction exhibited distinct synergistic effects on the formation and characteristics of emulsions, and the emulsions could demonstrate superior oxidative and storage stability. These findings could provide a novel strategy to extend the shelf life of cellulose-based emulsions and related products.

Development, characterization and underling mechanism of 3D printable quinoa protein emulsion gels by incorporating of different polysaccharides for curcumin delivery

Emulsion gels stabilized by food-grade polymers such as proteins and polysaccharides are edible 3D food printing inks with various applications in food industry. In this study, 3D printable quinoa protein emulsion gels with four polysaccharides incorporated were fabricated to delivery curcumin. The effect of inulin (INU), fucoidan (FU), dextran sulfate (DS), and sodium alginate (SA) on the microstructure, rheological properties, and 3D printing performance of quinoa protein emulsion gels were all investigated. The results showed that the incorporation of four polysaccharides promoted formation of tightly packed oil droplets within gel networks, along with enhanced hardness, water holding capacity, freeze-thaw stability and decreased swelling ratio of the QP emulsion gel. All samples exhibited shear thinning behavior and polysaccharides increased viscoelasticity of QP emulsion gel. The hydrophobic interactions and disulfide bond are the main chemical molecular force of emulsion gels, INU significantly increased the hydrogen bonds interactions, and anionic polysaccharide (FU, DS, and SA) significantly increased the electrostatic interactions. QP-INU exerted best printing performance as identified by preferable self-supporting capability and high line printing accuracy. The addition of polysaccharides improved the encapsulation efficiency of curcumin in QP emulsion gel. In vitro release property showed that FU increased the bioavailability of curcumin, DS and SA decreased bioavailability of curcumin with delayed digestion rate. This study demonstrated the potential of utilizing polysaccharides to improve the flexibility of QP emulsion gel for 3D printing functional food.

Effect of vegetable oils on the thermal gel properties of PSE-like chicken breast meat protein isolate-based emulsion gels

To enhance the gel properties of PSE (pale, soft, and exudative)-like chicken meat protein isolate (PPI), the effect of peanut, corn, soybean, and sunflower oils on the gel properties of PPI emulsion gels was investigated. Vegetable oils improved emulsion stability and gel strength and enhanced viscosity and elasticity. The gel strength of the PPI-sunflower oil emulsion gel increased by 163.30 %. The thermal denaturation temperature and enthalpy values were increased. They decreased the particle size of PPI emulsion (P < 0.05) and changed the three-dimensional network structure of PPI emulsion gels from reticular to sheet with a smooth surface and pore-reduced lamellar. They elevated the content of immobile water PPI emulsion gels, decreased the α-helix and β-turn, and increased the β-sheet and random coil. Vegetable oil improved the gel properties of PPI in the following order: sunflower oil > soybean oil > corn oil ≈ peanut oil > control group.

Design, characterization and digestibility of β-carotene-loaded emulsion system stabilized by whey protein with chitosan and potato starch addition

The physicochemical properties and gastrointestinal fate of β-carotene-loaded emulsions and emulsion gels were examined. The emulsion was emulsified by whey protein isolate and incorporated with chitosan, then the emulsion gels were produced by gelatinizing potato starch in the aqueous phase. The rheology properties, water distribution, and microstructure of emulsions and emulsion gels were modulated by chitosan combination. A standardized INFOGEST method was employed to track the gastrointestinal fate of emulsion systems. Significant changes in droplet size, zeta-potential, and aggregation state were detected during in vitro digestion, including simulated oral, stomach, and small intestine phases. The presence of chitosan led to a significantly reduced free fatty acids release in emulsion, whereas a slightly increasing released amount in the emulsion gel. β-carotene bioaccessibility was significantly improved by hydrogel formation and chitosan addition. These results could be used to formulate advanced emulsion systems to improve the gastrointestinal fate of hydrophobic nutraceuticals.

Self-constructed water-in-oil Pickering emulsions as a tool for increasing bioaccessibility of betulin

Self-constructed water-in-oil emulsions can be stabilized by a natural pentacyclic triterpenoid, betulin. A higher betulin concentration (3%) results in smaller emulsion droplet sizes. Microscopy, confocal laser scanning microscopy and rheology indicate that the stabilizing mechanism is attributed to betulin crystals on the emulsion interface and within the continuous phase, thereby enabling excellent freeze/thaw and thermal stability. The betulin Pickering emulsion (1%) significantly increased betulin bioaccessibility (22.4%) compared to betulin alone (0.2%) and betulin-oil physical mixture (7.9%). A higher level of betulin at 3% leads to smaller emulsion particle size, potentially resulting in a greater surface area. This, in return, promotes a higher release of free fatty acids (FFA), contributing to the release and solubilization of betulin from emulsions. Additionally, it leads to the formation of micelles, further increasing betulin bioaccessibility (29.3%). This study demonstrates Pickering emulsions solely stabilized by phytochemical betulin provides an innovative way to improve its bioaccessibility.

Impact of κ-Carrageenan on the Cold-Set Pea Protein Isolate Emulsion-Filled Gels: Mechanical Property, Microstructure, and In Vitro Digestive Behavior

More understanding of the relationship among the microstructure, mechanical property, and digestive behavior is essential for the application of emulsion gels in the food industry. In this study, heat-denatured pea protein isolate particles and κ-carrageenan were used to fabricate cold-set emulsion gels induced by CaCl2, and the effect of κ-carrageenan concentration on the gel formation mechanism, microstructure, texture, and digestive properties was investigated. Microstructure analysis obtained by confocal microscopy and scanning electron microscopy revealed that pea protein/κ-carrageenan coupled gel networks formed at the polysaccharide concentration ranged from 0.25% to 0.75%, while the higher κ-carrageenan concentration resulted in the formation of continuous and homogenous κ-carrageenan gel networks comprised of protein enriched microdomains. The hydrophobic interactions and hydrogen bonds played an important role in maintaining the gel structure. The water holding capacity and gel hardness of pea protein emulsion gels increased by 37% and 75 fold, respectively, through increasing κ-carrageenan concentration up to 1.5%. Moreover, in vitro digestion experiments based on the INFOGEST guidelines suggested that the presence of 0.25% κ-carrageenan could promote the digestion of lipids, but the increased κ-carrageenan concentration could delay the lipid and protein hydrolysis under gastrointestinal conditions. These results may provide theoretical guidance for the development of innovative pea protein isolate-based emulsion gel formulations with diverse textures and digestive properties.

Development and characterization of emulsion gels prepared via gliadin-based colloidal particles and gellan gum with tunable rheological properties for 3D printed dysphagia diet

Dysphagia, a condition characterized by difficulty swallowing, has emerged as a threat to health. Herein, we investigated the feasibility of preparing a novel 3D-printed dysphagia diet using emulsions and gellan gum. A gel network was facilitated by the inclusion of gellan gum, which also helped to reduce the size of the oil droplets. Emulsion gels (with 0.3 %-0.5 % gellan gum) were stable at 25 °C for 30 days and tolerated a high ionic concentration of 800 mmol L-1. Emulsion gels remained stable after heat treatment and centrifugation. The excellent stability of the emulsion gels was related to the three-dimensional network developed by the gellan gum. The rheological results validated the solid-state behavior, shear thinning behavior and structural recovery of emulsion gels. Emulsion gels with 0.3 %-0.5 % gellan gum were suitable for 3D printing since they had high printing accuracy, self-support, and smooth surface texture. International Diet Standardization Initiative (IDDIS) tests have shown that emulsion gels can be classified as a level 3-5 dysphagia diet. In addition, the bioaccessibility of astaxanthin increased 1.7 times after being encapsulated by emulsion gels. Overall, these results demonstrate the potential of emulsion gels in the development of novel 3D-printed diets for dysphagia and bioactive protection.

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.

Tuning whey protein isolate/hyaluronic acid emulsion gel structure to enhance quercetin bioaccessibility and in vitro digestive characteristics

Quercetin (Que), a health-promoting polyphenol, has limited applicability in food products due to its susceptibility to degradation in the gastrointestinal tract. To overcome this problem, Que-loaded emulsion gels were produced using whey protein isolate (WPI) and hyaluronic acid (HA) by combining heating and CaCl2 treatment. The effects of HA addition on the structural and rheological properties of the emulsion gels were evaluated, and the protective effect of the gel on Que under simulated digestion was investigated in vitro. Microstructural observations indicated that HA leads to a more compact and uniform network structure, which significantly enhances the textural and rheological properties of emulsion gels. In vitro digestion experiments revealed that WPI-HA emulsion gels exhibited a higher Que bioaccessibility (55.01%) compared to that produced by WPI alone (21.26%). This innovative delivery carrier has potential applications in food products to accomplish sustained nutrient release along with improved stability.

A comparative study of the impacts of preparation techniques on the rheological and textural characteristics of emulsion gels (emulgels)

A subtype of soft solid-like substances are emulsion gels (emulgels; EGs). These composite material's structures either consist of a network of aggregated emulsion droplets or a polymeric gel matrix that contains emulsion droplets. The product's rheological signature can be used to determine how effective it is for a specific application. The interactions between these structured system's separate components and production process, however, have a substantial impact on their rheological imprint. Therefore, rational comprehension of interdependent elements, their structural configurations, and the resulting characteristics of a system are essential for accelerating our progress techniques as well as for fine-tuning the technological and functional characteristics of the finished product. This article presents a comprehensive overview of the mechanisms and procedures of producing EGs (i.e., cold-set and heat-set) in order to determine the ensuing rheological features for various commercial applications, such as food systems. It also describes the influence of these methods on the rheological and textural characteristics of the EGs. Diverse preparation methods are the cause of the rheological-property correlations between different EGs. In many ways, EGs can be produced using various matrix polymers, processing techniques, and purposes. This may lead to various EG matrix structures and interactions between them, which in turn may affect the composition of EGs and ultimately their textural and rheological characteristics.

Green extraction of Milletia pinnata oil for the development, and characterization of pectin crosslinked carboxymethyl cellulose/guar gum herbal nano hydrogel

Milletia pinnata oil and Nardostachys jatamansi are rich sources of bioactive compounds and have been utilized to formulate various herbal formulations, however, due to certain environmental conditions, pure extract form is prone to degradation. Therefore, in this, study, a green hydrodistillation technology was used to extract M. pinnata oil and N. jatamansi root for the further application in development of pectin crosslinked carboxymethyl cellulose/guar-gum nano hydrogel. Both oil and extract revealed the presence of spirojatamol and hexadecanoic acid methyl ester. Varied concentrations (w/w) of cross-linker and gelling agent were used to formulate oil emulsion extract gel (OEEG1, OEG1, OEEG2, OEG2, OEEG3, OEG3, OEEG4, OEG4, OEEG5, OEG5), in which OEEG2 and OEG2 were found to be stable. The hydrogel displayed an average droplet size of 186.7 nm and a zeta potential of -20.5 mV. Endo and exothermic peaks and the key functional groups including hydroxyl, amide II, and amide III groups confirmed thermal stability and molecular structure. The smooth surface confirmed structural uniformity. Bactericidal activity against both Gram-positive (25.41 ± 0.09 mm) and Gram-negative (27.25 ± 0.01 mm) bacteria and anti-inflammatory activity (49.25%-83.47%) makes nanohydrogel a potential option for treating various infections caused by pathogenic microorganisms. In conclusion, the use of green hydrodistillation technology can be used to extract the bioactive compounds that can be used in formulation of biocompatible and hydrophobic nanohydrogels. Their ability to absorb target-specific drugs makes them a potential option for treating various infections caused by pathogenic microorganisms.

Physicochemical properties and in vitro digestion behavior of emulsion gels stabilized by rice bran protein aggregates: Effects of heating time and induction methods

To investigate the effects of heating time and induction methods on the physicochemical properties and in vitro digestion behavior of emulsion gels, rice bran protein aggregates (RBPAs) were formed by acid-heat induction (90 °C, pH 2.0) and the emulsion gels were further prepared by adding GDL or/and laccase for single/double cross-linked induction. Heating time affected the aggregation and oil/water interfacial adsorption behavior of RBPAs. Suitable heating (1-6 h) was conducive to faster and more adsorption of aggregates at the oil/water interface. While excessive heating (7-10 h) resulted in protein precipitation, which inhibited the adsorption at the oil/water interface. The heating time at 2, 4, 5 and 6 h was thus chosen to prepare the subsequent emulsion gels. Compared with the single cross-linked emulsion gels, the double-cross-linked emulsion gels showed higher water holding capacity (WHC). After simulated gastrointestinal digestion, the single/double cross-linked emulsion gels all exhibited slow-release effect on free fatty acid (FFA). Moreover, the WHC and final FFA release rate of emulsion gels were closely related to the surface hydrophobicity, molecular flexibility, sulfhydryl, disulfide bond and interface behavior of RBPAs. Generally, these findings proved the potential of emulsion gels in designing fat alternatives, which could provide a novel technique for the fabrication of low-fat food.

Advances in preparation and application of food-grade emulsion gels

Emulsion gel is a semi-solid or solid material with a three-dimensional net structure produced from emulsion through physical, enzymatic, chemical methods or their combination. Emulsion gels are widely used in food, pharmaceutical and cosmetic industries as carriers of bioactive substances and fat substitutes due to their unique properties. The modification of raw materials, and the application of different processing methods and associated process parameters profoundly affect the ease or difficult of gel formation, microstructure, hardness of the resulting emulsion gels. This paper reviews the important research undertaken in the last decade focusing on classification of emulsion gels, their preparation methods, the influence of processing method and associated process parameters on structure-function of emulsion gels. It also highlights current status of emulsion gels in food, pharmaceutical and medical industries and provides future outlook on research directions requiring to provide theoretical support for innovative applications of emulsion gels, particularly in food industry.

Targeted pH-responsive chitosan nanogels with Tanshinone IIA for enhancing the antibacterial/anti-biofilm efficacy

Persistent bacterial infection caused by biofilms is one of the most serious problems that threatened human health. The development of antibacterial agents remains a challenge to penetrate biofilm and effectively treat the underlying bacterial infection. In the current study, chitosan-based nanogels were developed for encapsulating the Tanshinone IIA (TA) to enhance the antibacterial and anti-biofilm efficacy against Streptococcus mutans (S. mutans). The as-prepared nanogels (TA@CS) displayed excellent encapsulation efficiency (91.41 ± 0.11 %), uniform particle sizes (393.97 ± 13.92 nm), and enhanced positive potential (42.27 ± 1.25 mV). After being coated with CS, the stability of TA under light and other harsh environments was greatly improved. In addition, TA@CS displayed pH responsiveness, allowing it to selectively release more TA in acidic conditions. Furthermore, the positively charged TA@CS were equipped to target negatively charged biofilm surfaces and efficiently penetrate through biofilm barriers, making it promising for remarkable anti-biofilm activity. More importantly, when TA was encapsulated into CS nanogels, the antibacterial activity of TA was enhanced at least 4-fold. Meanwhile, TA@CS inhibited 72 % of biofilm formation at 500 μg/mL. The results demonstrated that the nanogels constituted CS and TA had antibacterial/anti-biofilm properties with synergistic enhanced effects, which will benefit pharmaceutical, food, and other fields.

Comparison of properties and application of starch nanoparticles optimized prepared from different crystalline starches

Starch nanoparticles (SNPs) were produced by nanoprecipitation combined with ultrasonication with the use of different starches (corn, potato and sago starch) and used to stabilize Pickering emulsions. The orthogonal experiment was used to optimize preparation conditions of gelatinization pretreatment duration of 30 min, ultrasonic power of 600 W, and ultrasonic time of 40 min. Compared with native starch, the SNPs were spherical in shape and displayed a V-type crystalline structure with low relative crystallinity and higher degree of double-helix. Compared with native starch-Pickering emulsion, the SNP-Pickering emulsion had a smaller droplet size, more uniform distribution, clearer oil/water interface, and higher static stability of droplets. The sago SNP-Pickering emulsion had the great gelatinous structure and emulsion stability. In addition, the SNP-Pickering emulsion had the better loading efficiency and controlled release performance of curcumin. Meanwhile, the bioavailability of curcumin in sago SNP-Pickering emulsion was highest.

Characterization of bacterial cellulose nanofibers/soy protein isolate complex particles for Pickering emulsion gels: The effect of protein structure changes induced by pH

In this work, the influence of soy protein isolated at different pH values (1-9) on the self-assembly behaviors of bacterial cellulose nanofibers/soy protein isolate (BCNs/SPI) colloidal particles via anti-solvent precipitation were investigated. The results showed that the formation of BCNs/SPI at pH values of 1-5 was mainly driven by electrostatic interaction, while the formation of those at pH values of 5-9 was driven by weak molecular interactions including hydrogen bonding and steric-hindrance effect. The FTIR demonstrated that the conformation of protein involved a transition from order to disorder at the level of secondary structure as pH values were away from the isoelectric point. The fluorescence spectroscopy and UV-vis adsorption spectroscopy indicated that hydrophobic region of SPI at pH value of 5 displayed more exposed as compared with that at pH values away from the isoelectric point. The changes in structure conformation of SPI induced by pH values led to the changes in properties of the BCNs/SPI colloidal particles including particle size, microstructure, crystallinity, hydrophily, thermal stability, and rheological properties. Furthermore, the structures of BCNs/SPI colloidal particles at different pH values significantly affected the stability of Pickering emulsion gels stabilized by the corresponding complex colloidal particles. This study provided a theoretical basis for the design of food-grade Pickering emulsion gels stabilized by BCNs/SPI complex colloidal particles.

Carrageenan-Based Pickering Emulsion Gels Stabilized by Xanthan Gum/Lysozyme Nanoparticle: Microstructure, Rheological, and Texture Perspective

In this study, Pickering emulsion gels were prepared by the self-gel method based on kappa carrageenan (kC). The effects of particle stabilizers and polysaccharide concentrations on the microstructure, rheological characteristics, and texture of Pickering emulsion gels stabilized by xanthan gum/lysozyme nanoparticles (XG/Ly NPs) with kC were discussed. The viscoelasticity of Pickering emulsion gels increased significantly with the increase of kC and XG/Ly NPs. The results of temperature sweep showed that the gel formation mainly depended on the kC addition. The XG/Ly NPs addition could accelerate the formation of Pickering emulsion gels and increase its melting temperature (Tmelt), which is helpful to improve the thermal stability of emulsion gels. Cryo-scanning electron microscope (Cryo-SEM) images revealed that Pickering emulsion gel has a porous network structure, and the oil droplets were well wrapped in the pores. The hardness increased significantly with the increase of XG/Ly NPs and kC. In particular, the Pickering emulsion gel hardness was up to 2.9 Newton (N) when the concentration of kC and XG/Ly NPs were 2%. The results showed that self-gelling polysaccharides, such as kC, could construct and regulate the structure and characteristics of Pickering emulsion gel. This study provides theoretical support for potential new applications of emulsion gels as functional colloids and delivery systems in the food industry.

Progress in the Application of Food-Grade Emulsions

The detailed investigation of food-grade emulsions, which possess considerable structural and functional advantages, remains ongoing to enhance our understanding of these dispersion systems and to expand their application scope. This work reviews the applications of food-grade emulsions on the dispersed phase, interface structure, and macroscopic scales; further, it discusses the corresponding factors of influence, the selection and design of food dispersion systems, and the expansion of their application scope. Specifically, applications on the dispersed-phase scale mainly include delivery by soft matter carriers and auxiliary extraction/separation, while applications on the scale of the interface structure involve biphasic systems for enzymatic catalysis and systems that can influence substance digestion/absorption, washing, and disinfection. Future research on these scales should therefore focus on surface-active substances, real interface structure compositions, and the design of interface layers with antioxidant properties. By contrast, applications on the macroscopic scale mainly include the design of soft materials for structured food, in addition to various material applications and other emerging uses. In this case, future research should focus on the interactions between emulsion systems and food ingredients, the effects of food process engineering, safety, nutrition, and metabolism. Considering the ongoing research in this field, we believe that this review will be useful for researchers aiming to explore the applications of food-grade emulsions.

Antimicrobial and Anti-Inflammatory Activity of Low-Energy Assisted Nanohydrogel of Azadirachta indica Oil

Plant-based bioactive compounds have been utilized to cure diseases caused by pathogenic microorganisms and as a substitute to reduce the side effects of chemically synthesized drugs. Therefore, in the present study, Azadirachta indica oil nanohydrogel was prepared to be utilized as an alternate source of the antimicrobial compound. The total phenolic compound in Azadirachta indica oil was quantified by chromatography analysis and revealed gallic acid (0.0076 ppm), caffeic acid (0.077 ppm), and syringic acid (0.0129 ppm). Gas chromatography−mass spectrometry analysis of Azadirachta indica oil revealed the presence of bioactive components, namely hexadecenoic acid, heptadecanoic acid, ç-linolenic acid, 9-octadecanoic acid (Z)-methyl ester, methyl-8-methyl-nonanoate, eicosanoic acid, methyl ester, and 8-octadecane3-ethyl-5-(2 ethylbutyl). The nanohydrogel showed droplet size of 104.1 nm and −19.3 mV zeta potential. The nanohydrogel showed potential antimicrobial activity against S. aureus, E. coli, and C. albicans with minimum inhibitory, bactericidal, and fungicidal concentrations ranging from 6.25 to 3.125 (µg/mL). The nanohydrogel showed a significantly (p < 0.05) higher (8.40 log CFU/mL) value for Gram-negative bacteria E. coli compared to Gram-positive S. aureus (8.34 log CFU/mL), and in the case of pathogenic fungal strain C. albicans, there was a significant (p < 0.05) reduction in log CFU/mL value (7.79−6.94). The nanohydrogel showed 50.23−82.57% inhibition in comparison to standard diclofenac sodium (59.47−92.32%). In conclusion, Azadirachta indica oil nanohydrogel possesses great potential for antimicrobial and anti-inflammatory activities and therefore can be used as an effective agent.

Properties of soybean protein isolate/curdlan based emulsion gel for fat analogue: Comparison with pork backfat

To obtain an analogue of pork backfat (PBF), we combined emulsion and gel to fabricate emulsion gel, which was prepared by using soybean protein isolate (SPI) and curdlan (CL) through a facile heat-treatment method in this paper. The microstructures, rheology properties, water holding capacity and freeze-thawing stability of the emulsion gel were investigated. The results suggested that the SPI/CL-stabilized emulsion gel was thermal-irreversible, and SPI was the emulsifying agent of the emulsion gel. Oil contents significantly affect the water holding capacity and freeze-thawing stability of emulsion gel. Subsequently, the TPA, gel strength and color of emulsion gels with different oil contents were compared with PBF. The hardness, chewiness, springiness, and gel strength of emulsion gel with 10 wt% oil contents were no significant differences from that of PBF (P > 0.05). Hence, this SPI/CL based emulsion gel can be used as an analogue to PBF, providing an alternative ingredient for the development of plant-based low-fat meat products.

Physical Properties of Peanut and Soy Protein-Based Emulsion Gels Induced by Various Coagulants

Emulsions of peanut and soy proteins, including their major components (arachin, conarachin, glycinin and β-conglycinin), were prepared by ultrasonication (300 W, 20 min) at a constant protein concentration (4%, w/v) and oil fraction (30%, v/v). These emulsions were then induced by CaCl2, transglutaminase (TGase) and glucono-δ-lactone (GDL) to form emulsion gels. The optimum coagulant concentrations were obtained for peanut and soy protein-stabilized emulsion gels, such as CaCl2 (0.15 and 0.25 g/dL, respectively), TGase (25 U/mL) and GDL (0.3% and 0.5%, w/v, respectively). For the CaCl2-induced emulsion gels, the hardness of the β-conglycinin gel was the highest, whereas that of the conarachin gel was the lowest. However, when TGase and GDL were used as coagulants, the strength of the conarachin emulsion gel was the best. For the GDL-induced emulsion gels, microstructural analysis indicated that the conarachin gel showed more homogeneous and compact structures. The gelation kinetics showed that the storage modulus (G') of all the GDL-induced emulsions increased sharply except for the arachin-stabilized emulsion. The interactive force nature varied between conarachin and arachin emulsion gels. This work reveals that peanut conarachin could be used as a good protein source to produce emulsion gels when suitable coagulants are selected.

Enhancement of oil productivity of Mortierella alpine and investigation into the potential of Pickering oil-in-water emulsions to improve its oxidative stability

Mortierella alpine is an oleaginous fungi known for its tendency to produce oil and polyunsaturated fatty acid. Initial experiment indicated that magnesium oxide nanoparticles (MgONPs) accelerated glucose consumption and, consequently, oil production. After enhancement of Mortierella alpine CBS 754.68' oil production, the oxidative stability of the oil rich in long-chain polyunsaturated fatty acids (arachidonic acid) encapsulated by modified chitosan (CS) was assayed. To confirm the modification of CS, Fourier transform infrared spectroscopy (FTIR) spectrum indicated that the connection between CS and capric acid (CA) as well as stearic acid (SA) was well formed, leading to a considerable improvement in nanoparticle formation, measured by the SEM photographs, and physical and oxidative stability of emulsions. The oxidative stability of Mortierella alpine' oil emulsion in a period of 20 days at ambient temperature was monitored. Of all treated media, CS-SA nanoparticles were of the most oxidative stability. The rheological tests showed that viscosity behaviors were dominated by elastic behaviors in the impregnating emulsion with unmodified CS at the applied frequencies, and the elastic behavior of the emulsion sample prepared with CS-SA was slightly higher than that of the emulsion prepared with CS-CA. The results of redispersibility indicated that the powdered emulsion stabilized by CS-SA had the lowest water absorption.

Preparation of Pickering emulsion gels based on κ-carrageenan and covalent crosslinking with EDC: Gelation mechanism and bioaccessibility of curcumin

Pickering emulsions stabilized by zein/carboxymethyl dextrin nanoparticles were added to the κ-carrageenan-based gel matrix to prepare emulsion gels via EDC - induced covalent crosslinking. Texture, WHC and freeze-thaw stability of the emulsion gels increased after crosslinking. The Confocal laser scanning microscope and SEM suggested that droplet clusters could be observed in gel with higher concentration of emulsion. The rheological measurements indicated that the viscosity and gel-like structure were relied on crosslinking agent and emulsion concentration. The photothermal stability of curcumin was significantly enhanced after crosslinking. In addition, in vitro digestion study suggested that the bioaccessibility of curcumin in emulsion gel crosslinked was lower compared to emulsion gel without crosslinking agent. These studies might facilitate the preparation of emulsion gels with excellent stability for bioactive compounds delivery in food and pharmaceutical applications.