Double Gel Research Articles

Co-encapsulation of probiotic bacteria and fructooligosaccharides in basil seed gum-stabilized double emulsion gels: Probiotic viability and physicochemical properties

Double emulsions (DEs) present many potential applications for encapsulating and protecting probiotics. However, their high instability limit their real applications. To improve the prolonged stability of DEs, Lacticaseibacillus rhamnosus and Lactobacillus gasseri were separately co-encapsulated together in the presence of fructooligosaccharides (FOSs) and basil seed gum (BSG) within the internal (W1) and external (W2) aqueous phases of double emulsion gels (DEGs; W1-sol/O/W2-gel). Physical properties of DEGs, and viability of probiotics during heat processing, gastrointestinal digestion and storage were evaluated. Appropriate physical stability was observed during storage for 28 d at 4 ± 2 °C. The FOSs and microorganism type showed not effect on the droplet size (10.63 to 10.47 µm). Turbidimetry, physical stability, and morphological studies revealed the formation of aggregated droplets after 3 weeks. All DEGs presented high (>90 %) encapsulation efficiency. The viability of microencapsulated probiotics over time (14.89–14.08 %) and against simulated gastrointestinal conditions was higher than that of free cells. The encapsulation of bacteria in W1 in the presence of FOSs led to a significant improvement of viability against heat (only 1.35 % to 6.83 % reduction at 72 °C). L. gasseri showed a higher stability against environmental conditions. Finally, BSG-stabilized DEGs can be considered for increasing the viability of probiotic in functional foods.

Fabrication, characterization and transdermal properties of double cross-linked gel beads with 4-n-butylresorcinol

In this paper, sodium alginate (SA) -agarose double cross-linked gel beads were prepared to improve the solubility of 4-n-butylresorcinol and to reduce skin irritation. The wrappage material suitable for 4-nBR gel beads was SA-agarose double cross-linking material, and the internal inclusions were in the form of 4-n-butylresorcinol nanoemulsions (4-nBR NEs). Under the orthogonal fluorescence microscope, it was observed that the gel beads were spherical in shape, with smooth and rounded surfaces and permeable interiors. The encapsulation rate of the gel beads was 84.37±3.56%, and the average diameter was 1.93±0.21 mm. Scanning electron microscopy showed that the gel beads were spherical in shape. The cumulative leakage rate of the gel beads on the 35 th day was 4.72±0.06%, suggesting that the gel beads encapsulated 4-butylresorcinol to good effect and with high stability. This proves that the gel beads wrapped with 4-nBR are highly effective and stable. In vitro skin permeability assessment verified the good skin permeability of nanoemulsions (NEs).

Effect of gelled phases on the relevance of double emulsion gels for probiotics encapsulation, rheological properties, and stability

This study aimed to develop a stable double emulsion gel (DEG) based on whey protein cold-set gelation of the external water phase and carnauba wax-based solidification of the oil phase as a potential delivery system for probiotics in high-protein food products. The effect of the gelation of different phases on the microstructure, gel properties, and stability of DEGs under storage and freezing–thawing conditions and the viability of L. plantarum loaded in the inner water phase of DEGs were evaluated. The oil phase crystallization allowed the formation of stable DEGs during storage, showing negligible changes in consistency index, G′, and particle size after 56 d of storage and under four freeze–thaw cycles. The gelation of both the oil and external water phases allowed a stronger gel network formation, with a six times lower creaming index than non-gelled double emulsions. All samples demonstrated that the encapsulation of L. plantarum into the inner water phase of the DEG is beneficial for the storage stability of probiotics.

Engineering surfactant-free pickering double emulsions gels with different structures as low-calorie fat analogues: Tunable oral perception, inhibiting lipid digestion, and potent co-delivery for lycopene and epigallocatechin gallate

Structural design has been as a transformative strategy to create clean-label and well-nourished fat-based foods. Herin, surfactant-free, plant-based oil-in-water-in-oil (O/W/O) and water-in-oil-in-water (W/O/W) emulsions gels (EGs) were designed using protein microgels and fat crystals formed in situ, which achieved dual-interface Pickering stabilization. The suitability and difference of O/W/O and W/O/W EGs as fat analogues in maintaining fat texture, inhibiting lipid digestion, target release and bioactivity of co-loading epigallocatechin gallate (EGCG) and lycopene were examined. O/W/O and W/O/W EGs displayed own unique characteristics, and could be tailored to optimize their performance. O/W/O EGs provided smoother oral perception similar to butter. The multi-structure and interface modulation for double EGs achieved inhibiting lipid digestion, fat phase position mainly controlled the digestive process. Co-delivery systems exhibited synchronous release profiles, allowing a more obvious in-time sustained release of lycopene in O/W/O and EGCG in W/O/W EGs. Both co-delivery O/W/O and W/O/W showed anti-inflammatory bioactivity.

Double Network Gel Electrolyte with High Ionic Conductivity and Mechanical Strength for Zinc-Ion Batteries.

Gel electrolytes hold promise for stabilizing zinc-ion batteries (ZIBs), but achieving both high ionic conductivity and strong mechanical properties remains challenging. This work presents a double network gel electrolyte based on poly(N-hydroxymethyl acrylamide) (PNMA) and sodium alginate (SA), overcoming this trade-off. The PNMA network provides mechanical strength and water retention, while the SA network facilitates rapid zinc-ion (Zn2+) diffusion through tailored solvation. This double network gel exhibits a tensile strength of up to 838 kPa, significantly higher than previous reports. The SA network provides ion channels for rapid transport of hydrated Zn2+, enhancing the ionic conductivity to a ground-breaking 33.1 mS cm-1. This value is even higher than the liquid electrolytes. The growth of Zn dendrites is also suppressed due to the mechanical constraint and rapid ion conduction. In symmetrical cells, the PNMA/SA gel demonstrates exceptional cycling stability (>2000 h). Characterizations show this is because of reduced free water amount, hindering cathode material dissolution. The full cells with sodium vanadate cathode manifest a high capacity (364.8 mA h g-1 at 0.5 A g-1) and excellent capacity retention (83% after 2500 cycles at 10 A g-1). This double network design offers a way to achieve high-performance and stable ZIBs.

Fabrication, digestion behavior and β-carotene bioaccessibility of emulsion-filled double-network gel: Effect of corn fiber gum/soy protein isolate ratio and surfactant types

Emulsion fortified with β-carotene was added to corn fiber gum (CFG)/soy protein isolate (SPI) double network gel matrix to obtain emulsion-filled gels (EFG) via dual induction of laccase and glucono-δ-lactone. Protein digestion was accompanied by the release of β-carotene from gel matrix during in vitro digestion. The surfactant types and corn fiber gum/soy protein isolate ratio affected the β-carotene bioaccessibility via changing oil-water interfacial composition and emulsion particle size during in vitro digestion. As compared with Tween-20 EFGs, emulsion droplets released from SPI EFGs was more susceptible to flocculation, followed with coalescence due to proteolysis of interfacial SPI during gastric digestion. The resulting oil droplets with large particle size exhibited lower lipase adsorption, thus reducing the free fatty acid content and β-carotene bioaccessibility. The confocal laser scanning microscope (CLSM) observation confirmed that protein hydrolysate from gel matrix were adsorbed onto the oil-water interface competing with Tween-20 during intestinal digestion. For EFGs with higher CFG content, steric hindrance of CFG molecules and less emulsion release could inhibit droplet flocculation, thus enhancing β-carotene bioaccessibility.

Highly Selective Recovery of Gold by In Situ Magnetic Field-Assisted Fe/Co-MOF@PDA/NdFeB Double Network Gel.

There are enormous economic benefits to conveniently increasing the selective recovery capacity of gold. Fe/Co-MOF@PDA/NdFeB double-network organogel (Fe/Co-MOF@PDA NH) is synthesized by aggregation assembly strategy. The package of PDA provides a large number of nitrogen-containing functional groups that can serve as adsorption sites for gold ions, resulting in a 21.8% increase in the ability of the material to recover gold. Fe/Co-MOF@PDA NH possesses high gold recovery capacity (1478.87mg g-1) and excellent gold selectivity (Kd = 5.71mL g-1). With the assistance of an in situ magnetic field, the gold recovery capacity of Fe/Co-MOF@PDA NH is increased from 1217.93 to 1478.87mg g-1, and the recovery rate increased by 24.7%. The above excellent performance is attributed to the efficient reduction of gold by FDC/FC+, Co2+/Co3+ double reducing couple, and the optimization of the reduction reaction by the magnetic field. After the samples are calcined, high-purity gold (95.6%, 22K gold) is recovered by magnetic separation. This study proposes a forward-looking in situ energy field-assisted strategy to enhance precious metal recovery, which has a guiding role in the development of low-carbon industries.

Sustainable soil rehabilitation with multiple network structures of layered double hydroxide beads: Immobilization of heavy metals, fertilizer release, and water retention

The remediation of heavy metal-contaminated soils necessitated a holistic approach that encompassed water and fertilizer conservation alongside soil property restoration. This study introduced the synthesis of (poly)acrylamide-layered double hydroxide gel spheres (PAM-LDH beads), which were designed to simultaneously immobilize heavy metals, control the release of fertilizers, and enhance soil water retention. Laboratory soil experiments under diverse conditions highlighted the superior performance of PAM-LDH beads in the immobilization of hexavalent chromium (Cr(VI)). The layered double hydroxide (LDH) component was identified as the key player in Cr(VI) immobilization, with anion exchange being the predominant mechanism. Notably, the encapsulated urea within the beads was released independently of environmental influences, governed by a concentration gradient across the beads surface. This release process was characterized by an initial phase of absorptive swelling followed by a diffusive phase. The impact on plant growth was assessed, revealing that PAM-LDH beads significantly curtailed Cr(VI) accumulation and alleviated its phytotoxic effects. Changes in the carbon (C) and nitrogen (N) content of the plants suggested that the urea encapsulated within the beads served as a nutrient source, contributing to soil fertility. Moreover, the water-holding capacity and soil-water characteristic curves of PAM-LDH beads suggested that these superabsorbent beads could delay soil water evaporation. The observed shifts in microbial community structure provided evidence for the enhancement of soil carbon and nitrogen cycles, indicative of improved soil properties.

Janus hydrogel loaded with a CO2-generating chemical reaction system: Construction, characterization, and application in fruit and vegetable preservation

In this study, we inserted a dynamic chemical reaction system that can generate CO2 into Janus hydrogel (JH) to develop a multidimensional preservation platform that integrates hygroscopicity, antibacterial activity, and modified atmospheric capacity. The double gel system developed using sodium alginate/trehalose at a 1:1 ratio effectively encapsulated 90% of citric acid. Furthermore, CO2 loss was avoided by separately embedding NaHCO3/cinnamon essential oil and citric acid microcapsules into a gelatin pad to develop JH. Freeze-dried JH exhibited a porous and asymmetric structure, very strongly absorbing moisture, conducting water, and rapidly releasing CO2 and essential oils. Furthermore, when preserving various fruits and vegetables in practical settings, JH provided several preservation effects, including color protection, microbial inhibition, and antioxidant properties. Our study findings broaden the application of JH technology for developing chemical reaction systems, with the resulting JH holding substantial promise for cold chain logistics.

Natural Polyelectrolyte Hydrogels with Two Types of Cross-Links with Different Energy

For the first time, gels of a polymer cross-linked by two types of ionic cross-links of different energies, namely trivalent chromium (III) ions and divalent iron (II) ions, were prepared. The negatively charged polysaccharide xanthan, a polyelectrolyte of natural origin, was used as a polymer. A study of xanthan gels cross-linked with each cross-linker separately was carried out to identify the optimal concentrations of each cross-linker for the production of a double cross-linked gel. The mechanical properties of hydrogels under oscillatory shear deformations were then studied. It was demonstrated that the simultaneous use of two cross-linkers resulted in a synergistic increase in the elastic modulus (plateau storage modulus) compared to gels cross-linked with each cross-linker separately. For a gel with two types of cross-links, the elastic modulus was 16 Pa. In contrast, for gels cross-linked with either chromium (III) cations or iron (II) cations, the elastic modulus was approximately 0.6 and 0.5 Pa, respectively. The strong effect can be attributed to the different nature of cross-linking between xanthan macromolecules and chromium (III) and iron (II) cations, as well as the different strength of the cross-links formed. The optimal range of pH values was determined in which a synergistic increase in the elastic modulus of gels with two types of cross-links was observed compared to the corresponding gels cross-linked with each cross-linker separately. Consequently, the concurrent utilisation of two cross-linking agents that generate cross-links with disparate energy levels represents an efficacious strategy to improve the tensile strength of polymer hydrogels.

Tranexamic acid-loaded catechol-modified hyaluronic acid/carboxymethyl chitosan double cross-linked porous gel micropowders for rapid hemostasis and wound healing

Acquiring rapid and effective hemostasis remains a critical clinical challenge. Current researches focus on concentrating blood components to speed up the hemostatic while ignore the effect of anti-fibrinolysis in promoting blood coagulation. Herein, we designed a novel tranexamic acid (TA)-loaded physicochemical double cross-linked multifunctional catechol-modified hyaluronic acid-dopamine/carboxymethyl chitosan porous gel micropowders (TA&Fe3+@HA-DA/CMCS PGMs) for rapid hemostasis and wound healing. TA&Fe3+@HA-DA/CMCS PGMs exhibited high water absorption rate (505.9 ± 62.1 %) and rapid hemostasis (79 ± 4 s) in vivo. Catechol groups, Fe3+ and the protonated amino groups of CMCS induced bacterial death. Moreover, TA&Fe3+@HA-DA/CMCS PGMs displayed sufficient adhesion to a variety of wet rat tissues. TA&Fe3+@HA-DA/CMCS PGMs on various bleeding wounds, including rat liver injury and tail severed models showed excellent hemostasis performance. The TA&Fe3+@HA-DA/CMCS PGMs could promote the healing of full-thickness skin wounds on the backs of rats. The advantages of TA&Fe3+@HA-DA/CMCS PGMs including rapid hemostasis, effective wound healing, good tissue adhesion, antibacterial properties and ease of use make it potentially valuable in clinical application.

Soybean protein isolate-sodium alginate double network emulsion gels: Mechanism of formation and improved freeze-thaw stability

Soybean protein isolate (SPI) is widely used in the food industry. However, SPI-based emulsion gels tend to aggregate and undergo oiling-off during freeze-thawing. In this study, emulsion gels were prepared by a combination of heat treatment and ionic cross-linking using SPI and sodium alginate (SA) as raw materials. The focus was on exploring the mechanistic effects of the SPI-SA double network structure on the freeze-thaw stability of emulsion gels. The results showed that the addition of SA could form different types of network structures with SPI, due to different degrees of phase separation. In addition, SA appearing on the SPI network indicated that the addition of Ca2+ shielded the electrostatic repulsion between SPI and SA to form SPI-SA complexes. The disappearance of the characteristic peaks of SA and SPI in Fourier transform infrared spectroscopy analysis also confirmed this view. Low-field nuclear magnetic resonance data revealed that SA played a role in restricting water migration within the emulsion gels, increasing bound water content, and thereby improving the water-holding capacity of the emulsion gels. Therefore, the incorporation of SA improved the freeze-thaw stability of SPI emulsion gels. These findings offer a theoretical basis and technical support for SPI application in frozen products.

Studies on the Properties and Stability Mechanism of Double Emulsion Gels Prepared by Heat-Induced Aggregates of Egg White Protein-Oligosaccharides Glycosylation Products.

Multiple emulsions can dissolve some substances with different properties, such as hydrophilicity and lipophilicity, into different phases. They play an important role in protection, controlled release and targeted release of the encapsulated substances. However, it's poor stability has always been one of the main problems restricting its application in the food industry. For this reason, a heat-induced aggregate (HIA) of Maillard graft product of isomalto-oligosaccharides (IMO), as well as egg white protein (EWP), was used as hydrophilic emulsifier to improve the stability of W1/O/W2 emulsions. Moreover, gelatin was added into the internal aqueous phase (W1) to construct W1/O/W2 emulsion-gels system. The encapsulation efficiency of HIA-stabilized W1/O/W2 emulsions remained nearly unaltered, dropping by only 0.86%, significantly outperforming the conjugates and physical mixture of IMO and EWP in terms of encapsulation stability. The emulsion-gels system was constructed by adding 5% gelatin in the W1, and had the highest EE% and good salt and heat stability after 30 days of storage. This experiment provides guidance for improving the stability of W1/O/W2 emulsions system and its application in the package delivery of functional substances in the food field.

Characterization of feruloylated arabinoxylan - acorn starch double network gel composite film and its application in postharvest preservation of Agaricus bisporus

To obtain efficient natural food packaging materials, we utilized acorn starch (AS)-based film strengthened by feruloylated arabinoxylan (FAX) gel and additional retrogradation treatment to extend the shelf life of Agaricus bisporus (A. bisporus). Fourier transform infrared spectroscopy (FT-IR), confocal laser scanning microscopy (CLSM), and scanning electron microscopy (SEM) analyses showed that due to the strong hydrogen bonding between FAX and starch molecules, physical crosslinking occurred between FAX and starch molecules in the composite film, and the microstructure became more compact. Thermogravimetric, tensile strength and swelling degree analyses indicate that the composite film exhibits better thermal stability, mechanical properties, and waterproofing compared to the pure AS film. Consequently, after five days of storage, the moisture content of the A. bisporus packaged with our composite film was 7.53 times and 5.73 times higher than that of the control group and the commercially available PEF group, respectively. Moreover, it delayed the respiration or transpiration of A. bisporus (lower weight loss, relative conductivity, MDA content). This packaging film developed with the objective of eco-friendly and biodegradability has considerable application potential in food and other industries.

Enhancing the nonlinear rheological property and digestibility of mung bean flour gels using controlled microwave treatments: Effect of starch debranching and protein denaturation

In this study, we examined the possibility of using industrial microwave processing to enhance the gelling properties and reduce the starch digestibility of mung bean flour (MBF). MBF (12.6 % moisture) was microwaved at a power of 6 W/g to different final temperatures (100–130 °C), and then its structural and functional properties were characterized. The microwave treatment had little impact on the crystalline structure or amylose content of the starch, but it roughened the starch granule surfaces and decreased the short-range ordered structure and degree of branching. In addition, the extent of mung bean protein denaturation caused by the microwave treatment depended on the final temperature. Slightly denaturing the proteins (100 °C) did not affect the nature of the gels (protein phase dispersed in a starch phase) but the gel network became more compact. Moderately denaturing the proteins (110–120 °C) led to more compact and homogeneous starch-protein double network gels. Excessive protein denaturation (130 °C) caused the gel structure to become more heterogeneous. As a result, the facilitated tangles between starch chains by more linear starch molecules after debranching, and the protein network produced by moderate protein denaturation led to the formation of stronger gel and the improvement of plasticity during large deformation (large amplitude oscillatory shear-LAOS). Starch recrystallization, lipid complexion, and protein network retard starch digestion in the MBF gels. In conclusion, an industrial microwave treatment improved the gelling and digestive properties of MBF, and Lissajous curve has good adaptability in characterizing the viscoelasticity of gels under large deformations.

Preparation and drug release performance of different gelation type polysaccharide/β-lactoglobulin fiber composite gels

Self-assembled protein fibers have attracted much attention in the fields of medicine and food because of their high aspect ratio, polymorphic structure and strong surface hydrophobicity. In this study, three different gelation types of polysaccharides/β-lactoglobulin fiber (Fblg) composite gels, including ionic alginate-Fblg gels, synergistic xanthan-Fblg gels, and double network agar-Fblg gels, were first prepared. The interactions between the polysaccharides and the Fblgs, the microstructure and mechanical properties of the composite gels were investigated using the light scattering, scanning electron microscopy, rheology and texture analysis in order to reveal their formation mechanisms. Then the loading and release properties of the water-soluble drug 5-fluorouracil (5-FU) and the hydrophobic drug curcumin (Cur) through these composite gels were further studied with release mechanisms determined by fitting different release models. It was found that the mechanical properties of the composite gels were determined by the mesh density of the three-dimensional networks formed inside the gels. The network structure and mechanical strength of the alginate-Fblg gels became weaker with the increase of Fblg content at pH 4 due to their attractive interaction which hindered the binding of Ca2+ to ALG, while the network and the strength of the alginate-Fblg gels didn't change much at pH 7 due to the repulsion between Alg and Fblg. The xanthan-Fblg gels formed lamellar structures with enhanced gel network and mechanical strength due to the hydrogen bonding and the electrostatic interaction with Fblg. The Agar-Fblg composite gel formed at 60 °C (above the gelation temperature of agar of 40 °C) had a denser double network structure and higher mechanical strength than that formed at 0 °C due to inhibition of diffusion of Ca2+ as salt bridges for Fblg. The hydrophilic drugs were loaded in the meshes of the composite gels and their release was determined by the structure of the composite gel networks, whereas the hydrophobic drugs were loaded by attaching to the Fblgs in the composite gels and their release was determined by the loading ability and strength of the gels. The study not only provided a new idea for the preparation and application of polysaccharide-protein fiber composite hydrogels, but also provided insights for improving the efficiency of drug carriers.

Ex vivo UV-C Protective Effect of Aloe vera

Chronic exposure to UV-C can cause sunburn, skin cancer, oxidative stress as well as photo-aging. Many herbs and plant extracts have recently been recognized as a potential source of sunscreen due to their UV-absorbing properties. Aloe vera L., which has been used for therapeutic purposes by humans for centuries, is also among these plants. In this study, it was aimed to reveal the sunscreen properties of the latex and gel parts of A. vera and the effect of these properties on cells exposed to UV rays. In this study, primarily, the lethal effect of UV-C rays on healthy cells was observed over time. Then, the latex and gel parts of the obtained A. vera plant were separated and spread on the surface of petri dishes as a single and double layer. By adding a determined number of cells of the petri dishes, the protection of A. vera against the lethal effect of 1, 1.5 and 2 hours of UV-C exposure was investigated. According to the study findings, it was determined that both parts of A. vera protect cells against UV-C damage. It is quite remarkable that while all the cells in the control group died as a result of UV-C exposure for 2 hours, vitality was still observed in the double layer latex and gel groups. From this point of view, it has been shown in this study that a protective product that can be made using A. vera can prevent the damages that may develop due to UV-C exposure.

O1/W/O2 double emulsion gels based on nanoemulsions and Pickering particles for co-encapsulating quercetin and cyanidin: A functional fat substitute

An O1/W/O2 double emulsion gel, as a functional fat substitute and based on nanoemulsions and hydrophobic Pickering particles, is prepared by two-step emulsification to co-encapsulate hydrophilic cyanidin and hydrophobic quercetin. Nanoemulsions loading quercetin are fabricated by Tween-80 and combining high-speed and high-pressure emulsification. Phytosterol nanoparticles stabilize the W-O2 interface of the secondary emulsion to load cyanidin in the W phase. The concentration of Tween-80 is optimized as 0.3% by the droplet size and viscosity of nanoemulsions. The structural stability of double emulsion gels will be weakened along with the increase of nanoemulsions, showing lower modulus and encapsulation efficiency (EE) and bigger droplets. In double emulsion gels, the EE of quercetin and cyanidin reaches 93% and 85.6%, respectively. Analysis of molecular interaction indicates that Tween-80 would decrease the in-situ hydrophobicity of phytosterol nanoparticles by hydrogen bonding adsorption, thereby weakening the emulsification. The pH-chromic 3D printing of double emulsion gels is designed according to the pH sensitivity of cyanidin. Texture profile analysis is performed to test the textural properties of 3D-printed objects. The simulated digestion is conducted on double emulsion gels. The double emulsion gel with fewer nanoemulsions is beneficial for protecting quercetin and improving the delivery due to the higher structural stability, while that with more nanoemulsions is conducive to the digestion of cyanidin and camellia oil due to weakened semi-solid properties. This double emulsion gel further simulates fat tissues by co-encapsulating hydrophilic and hydrophobic substances, promoting the application of fat substitutes in the food industry.

Supramolecular polymer-based gel fracturing fluid with a double network applied in ultra-deep hydraulic fracturing

A gel based on polyacrylamide, exhibiting delayed crosslinking characteristics, emerges as the preferred solution for mitigating degradation under conditions of high temperature and extended shear in ultralong wellbores. High viscosity/viscoelasticity of the fracturing fluid was required to maintain excellent proppant suspension properties before gelling. Taking into account both the cost and the potential damage to reservoirs, polymers with lower concentrations and molecular weights are generally preferred. In this work, the supramolecular action was integrated into the polymer, resulting in significant increases in the viscosity and viscoelasticity of the synthesized supramolecular polymer system. The double network gel, which is formed by the combination of the supramolecular polymer system and a small quantity of Zr-crosslinker, effectively resists temperature while minimizing permeability damage to the reservoir. The results indicate that the supramolecular polymer system with a molecular weight of (268–380) × 104 g/mol can achieve the same viscosity and viscoelasticity at 0.4 wt% due to the supramolecular interaction between polymers, compared to the 0.6 wt% traditional polymer (hydrolyzed polyacrylamide, molecular weight of 1078 × 104 g/mol). The supramolecular polymer system possessed excellent proppant suspension properties with a 0.55 cm/min sedimentation rate at 0.4 wt%, whereas the 0.6 wt% traditional polymer had a rate of 0.57 cm/min. In comparison to the traditional gel with a Zr-crosslinker concentration of 0.6 wt% and an elastic modulus of 7.77 Pa, the double network gel with a higher elastic modulus (9.00 Pa) could be formed only at 0.1 wt% Zr-crosslinker, which greatly reduced the amount of residue of the fluid after gel-breaking. The viscosity of the double network gel was 66 mPa s after 2 h shearing, whereas the traditional gel only reached 27 mPa s.

Improved stability and mechanical properties of citrus pectin-zein emulsion gels by double crosslinking with calcium and transglutaminase

The low water solubility of zein severely limits its industrial application. In this study, the emulsifying performance and stability of zein were improved by electrostatically compounding different ratios of citrus pectin (CP) with zein to obtain zein-CP composite particles (ZCPs). When the mass ratio of CP to zein was 1: 2 (C1Z2), the composite particles showed the smallest particle size, and the C1Z2 stabilized Pickering emulsion (C1Z2-PE) exhibited excellent physical and environmental stability. The ZCPs stabilized emulsions were further cross-linked by transglutaminase (TGase) and Ca2+, resulting in the formation of emulsion gels with increased mechanical properties. Macroscopic and microscopic morphology analysis demonstrated the successful preparation of the emulsion gels. Through the rheological study and texture analysis, it was observed that the double cross-linked emulsion gels exhibited a remarkable improvement in apparent viscosity and gel hardness. This research offers a new strategy and technical reference for the development of new gel-based products.