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Porphyra yezoensis has attracted much attention due to its gelling properties and bioactivity. In this study, the chemical structure of Porphyra yezoensis polysaccharides (PYPSs) was characterized, and the effects of concentration, temperature, pH, and calcium ion (Ca2+) addition on the rheological properties of PYPS were systematically investigated. Chemical composition analysis indicated that PYPS primarily contained galactose (89.76%) and sulfate (15.57%). Rheological tests demonstrated that PYPS exhibited typical pseudoplastic properties, with apparent viscosity increasing with an increasing concentration. Temperature elevation from 30 °C to 90 °C weakened the intermolecular forces and reduced the apparent viscosity, whereas neutral pH (7.0) provided an optimal electrostatic equilibrium to maintain the highest viscosity. Ca2+ could modulate the interactions between PYPS molecules and affect the formation of the gel network structure. When the Ca2+ concentration reached the optimal value of 6 mM, the calcium bridges formed between Ca2+ and PYPS molecules not only enhanced the rheological behavior and textural properties but also formed a smooth and well-ordered network structure, achieving the highest value of fractal dimension (Df = 2.9600), though excessive Ca2+ disrupted this well-ordered structure. Furthermore, PYPS possessed significant scavenging ability against DPPH, ABTS, and HO• radicals, demonstrating its potential application as a natural antioxidant in functional foods. [ABSTRACT FROM AUTHOR]

Cellulose nanocrystals are charged rod‐like nanoparticles that can spontaneously organize into cholesteric mesophases upon evaporation to produce photonic films with circular polarization. In this study, it is demonstrated that through the modulation of gelation and kinetics of phase separation via the addition of a strong gelating agent, xanthan gum, the cellulose nanocrystals produce flexible photonic films with improved optical purity in terms of circular reflection. The work reveals the self‐assembly behavior as a function of xanthan gum through the volume depletion mechanism, quenching of the tactoids at the early stages of the self‐assembly, and evaporation into cholesteric films. In dried films, this leads to significant reduction in the domain size and the absence of domain folding which is usually caused by the merger of large tactoids. Despite the reduction in metallic iridescence caused by the entrapment of cellulose nanocrystal tactoids, the films exhibit improved macroscopic color uniformity across 30–60° observation angles, which implies a combined effect of surface texturing and scattering of visible light induced by incorporating xanthan gum within the co‐assembled structure. Overall the work provides new insights into the gelation mechanism in hybrid cellulose nanocrystal systems and presents an efficient approach to control the self‐assembly and macroscopic color appearance. [ABSTRACT FROM AUTHOR]

The industrial application of pea protein is limited due to its poor gelation properties. This study aimed to evaluate the effects of psyllium husk powder (PHP) on improving the rheological, textural, and structural properties of heat-induced pea protein isolate (PPI) gel. Scanning electron microscopy (SEM), intermolecular forces analysis, the quantification of the surface hydrophobicity and free amino groups, and Fourier transform infrared spectroscopy (FTIR) were conducted to reveal the inner structures of PPI-PHP composite gels, conformational changes, and molecular interactions during gelation, thereby clarifying the underlying mechanism. The results showed that moderate levels of PHP (0.5–2.0%) improved the textural properties, water holding capacity (WHC), whiteness, and viscoelasticity of PPI gel in a dose-dependent manner, with the WHC (92.60 ± 1.01%) and hardness (1.19 ± 0.02 N) peaking at 2.0%. PHP significantly increased surface hydrophobicity and enhanced hydrophobic interactions, hydrogen bonding, and electrostatic interactions in PPI-PHP composite gels. Moreover, the electrostatic repulsion between anionic PHP and negatively charged PPI in a neutral environment prevented the rapid and random aggregation of proteins, thereby promoting the formation of a well-organized gel network with more β-sheet structures. However, the self-aggregation of excessive PHP (3.0%) weakened molecular interactions and disrupted the continuity of protein networks, slightly reducing the gel strength. Overall, PHP emerged as an effective natural gel enhancer for the production of pea protein gel products. This study provides technical support for the development of innovative plant protein-based foods with strong gel properties and enriched dietary fiber content. [ABSTRACT FROM AUTHOR]

Over the years, the production of eggs has increased tremendously, with an estimated global egg production of 9.7 billion by 2050. Further processing of shell eggs to egg products has gained growing popularity. Liquid egg yolks, an innovative form of egg replacement, still suffer from short shelf‐life issues, and freezing has been applied to maintain freshness. An undesirable phenomenon called "gelation" was found during the production of frozen egg yolks, which has attracted numerous scholars to study its mechanism and quality control methods. Therefore, we comprehensively reviewed the history of the studies on frozen egg yolks, including the production procedure, the fundamentals of freezing, the gelation mechanism, the factors affecting gelation behaviors, and the techniques to control the gelation behaviors of frozen egg yolks. Reporting the production procedure and freezing fundamentals of frozen egg yolks will give readers a better understanding of the science and technological aspects of frozen egg yolks. Furthermore, a comprehensive summary of the mechanism of egg yolk gel formation induced by freeze–thawing and relevant control techniques will provide insights to researchers and manufacturers in the field of frozen egg processing. [ABSTRACT FROM AUTHOR]

A novel fire-preventing composite gel, mainly made from steel slag (SS) and silica fume (SF), was created for a coal mine’s spontaneous combustion. The gelation mechanism of the steel slag-based composite gel (SSG) was investigated using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and field emission scanning electron microscopy (SEM). The findings suggest that SSG is generated through the processes of hydration and geopolymerization involving SS and SF. And in the alkaline milieu of a 1.5 M water glass solution, SSG manifests enhanced strength and water retention capacities. Moreover, the fire prevention and extinguishing performance of the SSG was analyzed and verified using low-temperature oxidation, thermogravimetry, and low temperature nitrogen adsorption experiment (LTNA). The SSG has proven highly effective in suppressing spontaneous coal combustion by inhibiting CO production, raising the coal oxidation temperature, and reducing the contact area between oxygen and the coal body.

Gelation, an important quality attribute of meat products, significantly influences the appearance, flavor, and texture of meat products. Enhancing gelation in meat products holds immense importance in improving the production process and the quality. The gel properties of meat products are influenced by the content and structure of protein aggregates and the aggregation rate during processing. Protein additives have the potential to partially replace myofibrillar proteins in gelation and emulsification properties, leading to cost reduction, and therefore have attracted much research interest for the development of new meat products and the optimization of the processing technology. This paper summarizes recent studies on the gelation mechanism of myofibrillar proteins, and reviews the properties and applications of the major protein additives as well as recent progress in using protein additives combined with polysaccharide colloids, enzymes or phosphates to enhance the gelation of meat products. This review may serve as a valuable reference for enhancing the quality of gel-type meat products.

To investigate the effect of the chemical composition of a metal–organic crosslinker on the performances of fracturing fluid in high-temperature conditions, four zirconium (Zr) crosslinkers and one aluminum–zirconium (Al-Zr) crosslinker with a polyacrylamide were used. The crosslinkers possessed the same Zr concentration, but they differed in component amounts and the order of the addition of the crosslinker components, leading to different chemical compositions in the crosslinkers. The fracturing fluids prepared by different tested crosslinkers were compared in terms of properties of rheological behavior, sand-carrying ability, microstructure, and gel breaking characteristics. The results showed that the fracturing fluids prepared by zirconium lactic acid, ethanediamine, and sorbitol crosslinkers offered the slowest viscosity development and highest final viscosity compared to the zirconium lactic acid crosslinker and the zirconium lactic acid and ethanediamine crosslinker. The zirconium sorbitol, lactic acid, and ethanediamine crosslinker exhibited a faster crosslinking rate and a higher final viscosity than the zirconium lactic acid, ethanediamine, and sorbitol crosslinker; the crosslinker showed crosslinking density and crosslinking reactivity, resulting in more crosslinking sites and a higher strength in the fracturing fluid. The Al-Zr-based crosslinker possessed better properties in temperature and shear resistance, viscoelasticity, shear recovery, and sand-carrying ability than the Zr-based crosslinker due to the synergistic crosslinking effect of aluminum and zirconium ions. The tertiary release gelation mechanism of the Al-Zr-based fracturing fluid achieved a temperature resistance performance in the form of continuous crosslinking, avoiding the excessive crosslinking dehydration and reducing viscosity loss caused by early shear damage. These results indicated that the chemical compositions of metal–organic crosslinkers were important factors in determining the properties of fracturing fluids. Therefore, the appropriate type of crosslinker could save costs without adding the additional components required for high-temperature reservoirs. [ABSTRACT FROM AUTHOR]

Heating is a vital step in the gelation of surimi. Conventional water bath heating (WB) has the advantages of easy operation and low equipment requirements. However, the slow heat penetration during WB may lead to poor gel formation or gels prone to deterioration, especially with one-step heating. The two-step WB is time-consuming, and a large amount of water used tends to cause environmental problems. This review focuses on key factors affecting the quality of surimi gels in various heating technologies, such as surimi protein structure, chemical forces, or the activity of endogenous enzymes. In addition, the relationships between these factors and the gel performance of surimi under various heating modes are discussed by analyzing the heating temperature and heating rate. Compared with WB, the gel performance can be improved by controlling the heating conditions of microwave heating and ohmic heating, which are mainly achieved by changing the molecular structure of myofibrillar proteins or the activity of endogenous enzymes in surimi. Nevertheless, the novel thermal technologies still face several limitations and further research is needed to realize large-scale industrial production. This review provides ideas and directions for developing heat-induced surimi products with excellent gel properties. [ABSTRACT FROM AUTHOR]

In situ gel systems have emerged as promising drug delivery platforms due to their numerous benefits, including increased patient compliance and decreased administration frequency. The potential of in situ gel extends beyond its formulation benefits, with the ability to transform medical treatment by enhancing drug delivery, offering personalized therapies, and introducing innovative approaches. Ongoing research and the efforts of pharmaceutical companies are dedicated to exploring the vast opportunities presented by in situ gel, pushing the limits of innovation in the field of drug delivery. The selection of suitable polymers is critical for the development of in situ gel formulations. Additionally, consideration of drug‐polymer compatibility ensures the stability and efficacy of the drug within the gel matrix. Formulation considerations play a pivotal role in the development of effective in situ gel systems. They have shown great potential in drug delivery systems, tissue engineering, and regenerative medicine. The ability to prolong gastric retention time, targeted delivery, and localized drug release are among the advantages offered by in situ gels. Although in situ gel technology has shown significant advancements, challenges remain, including stability and shelf‐life issues, biocompatibility and safety concerns, and the need for further research and development. Future directions focus on overcoming these challenges and exploring new applications and advancements in the field. In conclusion, in situ gel systems provide a versatile and promising drug delivery and tissue engineering platform. However, further research and development are essential to address the challenges and fully harness the potential of this innovative technology. [ABSTRACT FROM AUTHOR]

The objective of this study is to enhance the comprehension of the mechanism of enzymatic gelation in milk by investigating statistically significant changes in milk viscosity and carrying out corresponding electron microscopic studies of the process of structure formation at the enzymatic stage of coagulation using various enzyme preparations. Employing a non-destructive method (Hot-Wire) to monitor viscosity, we were able to confirm a decrease in viscosity during the middle of this stage and identify a previously undescribed peak in viscosity change at the end of the enzymatic stage. By conducting parallel studies utilizing transmission electron microscopy and various methods of specimen preparation, it was possible to discover that a hierarchical transformation process in the protein component of milk started at the end of the enzymatic stage of gelation in milk. This process is triggered by a cooperative conformational transition in casein micelle clusters, which leads to a series of increasingly energy-intensive reactions resulting in the transformation of loosely bound micelle clusters into denser aggregates. The final structure of the milk gel primarily consists of the previously formed individual micelle aggregates. It was noted that no changes in the microstructure of the milk gel were observed during the enzymatic stage of gelation when milk-clotting enzymes (MCEs) of animal, plant, and microbial (GMO) origins were used. Furthermore, investigations into the molecular weight distribution of soluble protein substances in samples generated with different types of MCEs revealed that the enzyme derived from the fungi of Rhizomucor miehei had a greater proteolytic effect on milk proteins compared to other variants of MCEs. [ABSTRACT FROM AUTHOR]

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The aim of this study is to enhance the comprehension of the mechanism of enzymatic gelation in milk by visualizing the evolution of its microstructure through transmission electron microscopy. In order to minimize the potential for artifacts during the preparation process and eliminate any possible difficulties in interpreting the resulting images, three distinct methods were employed in the research: shading the surface topography with vacuum deposition of heavy metal, negative staining of the specimen with a heavy metal solution and replicating a cleavage of a quick-frozen sample. The selection of time intervals for sampling the gel during its evolution is determined by the most probable significant modifications in the resulting gel. Based on the research, it has been shown that natural milk is a nonequilibrium system from the perspective of statistical thermodynamics. A notable observation is that the glycomacropeptides forming the hair layer on the surface of casein micelles are unevenly distributed, leading to the formation of micelle dimers and trimers. It has been determind that during the initial stage of enzymatic gelation in milk, clusters of loosely bound micelles are formed in areas with the highest concentration. The formation of micelle chains is absent at this stage due to the non-anisometric nature of micelles and the energetic disadvantage of their formation. It has been found that under the influence of enzymatic gelation near the gel point, a hierarchical process involving the transformation of the milk’s protein component is activated. The trigger mechanism for this process is a cooperative conformational transition in clusters of casein micelles, which initiates a chain of more energy-intensive reactions in the following sequence: hydro­phobic interactions → hydrogen bridges → electrostatic interactions → calcium bridges. The result is the conversion of loosely bound micelle clusters into denser aggregates, predominantly contributing to the formation of milk curd. It is worth noting that gelation in milk can be regarded as a process that reduces the free energy of the dispersed system. Understanding the correlation between the decrease in the free energy value during gelation and the physical properties of the finished cheese and other dairy products continues to be a relevant area of research.

The industrial application of pea protein is limited due to its poor gelation properties. This study aimed to evaluate the effects of psyllium husk powder (PHP) on improving the rheological, textural, and structural properties of heat-induced pea protein isolate (PPI) gel. Scanning electron microscopy (SEM), intermolecular forces analysis, the quantification of the surface hydrophobicity and free amino groups, and Fourier transform infrared spectroscopy (FTIR) were conducted to reveal the inner structures of PPI-PHP composite gels, conformational changes, and molecular interactions during gelation, thereby clarifying the underlying mechanism. The results showed that moderate levels of PHP (0.5–2.0%) improved the textural properties, water holding capacity (WHC), whiteness, and viscoelasticity of PPI gel in a dose-dependent manner, with the WHC (92.60 ± 1.01%) and hardness (1.19 ± 0.02 N) peaking at 2.0%. PHP significantly increased surface hydrophobicity and enhanced hydrophobic interactions, hydrogen bonding, and electrostatic interactions in PPI-PHP composite gels. Moreover, the electrostatic repulsion between anionic PHP and negatively charged PPI in a neutral environment prevented the rapid and random aggregation of proteins, thereby promoting the formation of a well-organized gel network with more β-sheet structures. However, the self-aggregation of excessive PHP (3.0%) weakened molecular interactions and disrupted the continuity of protein networks, slightly reducing the gel strength. Overall, PHP emerged as an effective natural gel enhancer for the production of pea protein gel products. This study provides technical support for the development of innovative plant protein-based foods with strong gel properties and enriched dietary fiber content.

To investigate the effect of K+ on the properties and mechanism of the composite gel system consisting of tamarind gum and κ-carrageenan, four methods including rheology, texture analysis, microstructure, and infrared spectroscopy were used to investigate the properties and structure of the composite gel with different K+ additions. The rheological results showed that the addition of K+ increased the modulus of the gel system and decreased the compliance and total deformation. When the addition of K+ increased to 15 mmol/L, the apparent viscosity reached its highest value of 2690 Pa·s. The results of texture analysis revealed that the strength and hardness of the gel system increased with the addition of K+, but its elasticity and cohesiveness decreased relatively. Infrared spectroscopy and microstructure demonstrated that K+ could promote the interaction between tamarind gum and κ-carrageenan, the gel pores tend to be dense and uniform, and the inter-pore walls were most regular and strong at the K+ addition of 15 mmol/L. The results showed that the addition of K+ could make the gel system exhibit better viscoelasticity and anti-deformation, and make the network structure more compact, which would provide a theoretical reference for the application of tamarind gum and κ-carrageenan in compounding.

Various polymers are the most widely used product to provide rheology for water-based fracturing fluid, however, they have weaknesses in terms of temperature resistance and salt resistance. The change from organic-based to inorganic thickeners may be a meaningful attempt. Inorganic silica gel is a potentially alternative viscosifier with high temperature resistance, excellent proppant carrying capacity, and can even be used to prepare fracturing fluids with high salinity of produced water. In this paper, the silica gel viscosifier was firstly prepared using sol–gel method. Then, the gelation time under different influencing factors and rheological properties of the silica gel viscosifier were studied in detail. Subsequently, the silica gel-based fracturing fluid was prepared by adding the desired amount of drag reducer to the silica sol solution, and the properties of novel fracturing fluid were systematically evaluated with regard to the temperature and shearing resistance, drag reduction, and static proppant suspension. The potential mechanism of gelation process by syneresis of silica gel was revealed at last. Results showed that the microstructure of silica gel is synthetic, amorphous and consists of a three-dimensional network of SiO2 particles. The effect of SiO2 concentration on the gelation time is more pronounced than other factors such as temperature and pH level. In addition, the silica gel viscosifier exhibits strong salt resistance, whether monovalent ions (Na+, K+) or divalent ions (Ca2+, Mg2+), and the gelation time decreased significantly with the increase of salt concentration. The shear viscosity of the silica gel viscosifier increased with an increase of SiO2 concentration, showing shear thinning behavior as well. Meanwhile, the silica gel-based fracturing fluid prepared by adding drag reducer into silica sol solution also presented excellent thermal stability and shear resistance, drag reduction and proppant suspension performances. The retained viscosity can be maintained above 50 mPa·s after shearing at 180 °C for 60 mins; the drag reduction rate shows a declining trend at high displacement due to the gelation process; the settling rate of 40/70 mesh sand proppant with 35 % sand ratio is less than 30 % after standing at 90 °C for 4 h. In addition, the gelation process is essentially the formation of Si-O-Si linkage by dehydration between SiO2 particles, which is gradually extended at both ends and sides of the chain, and eventually forms a rigid, highly porous, entangled network. Findings found in this study provide a research basis for the popularization and application of silica gel-based fracturing fluid.

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To expand the applicability of gel fracturing fluids in ultra-high-temperature reservoirs, a temperature-resistant polymer was synthesized using the solution polymerization method. Subsequently, an ultra-high-temperature-resistant polymer gel was formulated by incorporating an organic zirconium crosslinking agent. A comprehensive investigation was carried out to systematically study and evaluate the steady shear property, dynamic viscoelasticity, and temperature and shear resistance performance, as well as the core damage characteristics of the polymer gel. The obtained results demonstrate that the viscosity remained at 147 mPa·s at a temperature of 200 °C with a shear rate of 170 s−1. Compared with the significant 30.9% average core damage rate observed in the guanidine gum fracturing fluid, the core damage attributed to the polymer gel was substantially mitigated, measuring only 16.6%. Finally, the gelation mechanism of the polymer gel was scrutinized in conjunction with microscopic morphology analysis. We expect that this study will not only contribute to the effective development of deep and ultradeep oil and gas reservoirs but also furnish a theoretical foundation for practical field applications. [ABSTRACT FROM AUTHOR]

So far, it has been difficult to directly compare diverse characteristic gelation mechanisms over different length and time scales. This paper presents a universal water structure analysis of several gels with different structures and gelation mechanisms including polymer gels, supramolecular gels composed of surfactant micelles, and cement gels. The spatial distribution of water molecules was analyzed at molecular level from a diagram of the relaxation times and their distribution parameters (τ–β diagrams) with our database of the 10 GHz process for a variety of aqueous systems. Polymer gels with volume phase transition showed a small decrease in the fractal dimension of the hydrogen bond network (HBN) with gelation. In supramolecular gels with rod micelle precursor with amphipathic molecules, both the elongation of the micelles and their cross-linking caused a reduction in the fractal dimension. Such a reduction was also found in cement gels. These results suggest that the HBN inevitably breaks at each length scale with relative increase in steric hindrance due to cross-linking, resulting in the fragmentation of collective structures of water molecules. The universal analysis using τ–β diagrams presented here has broad applicability as a method to characterize diverse gel structures and evaluate gelation processes. [ABSTRACT FROM AUTHOR]

This article reviews different studies on the gelation mechanisms and network structural characteristics in polysaccharide gels at the different length scales of observation: macroscopic, microscopic, and molecular. Rheological and micro-DSC (Differential Scanning Calorimetry) measurements represent the macroscopic viewpoints on the gelation of pure kappa-carrageenan (KC), iotacarrageenan (IC) and KC/IC mixtures. Microscopic rheological properties observed using particle tracking experiments have been used to elucidate the formation of heterogeneous networks of KC-rich and IC-rich domains in mixed KC/IC gels, and facilitate observations of their aging process. Nuclear magnetic resonance (NMR) relaxation time measurements provide information on the tumbling motion and local mobility; these molecular-level experiments are presented for agar, agarose, native gellan and deacylated gellan chains. NMR diffusion measurements of gelling and probe polymers give insights into the conformational changes, aggregation and network formation, and aging mechanisms, and are presented for all studied polysaccharides. [ABSTRACT FROM AUTHOR]

In this paper, the gel properties of sodium alginate with Y3+, Ce3+, La3+ and Er3+ were studied. By studying the mechanical properties, equilibrium water content, ion exchange rate and gel mechanism of seaweed rare earth gel, it was found that: The coordination form of rare earth ions and carboxyl group in sodium alginate was pseudo-bridged monodentate coordination and bridge coordination. At the same time, the special three-dimensional network structure of the rare earth gel was formed through the planar and non-planar geometry formed by intramolecular and intermolecular chelation, and the gel strength of the gel formed by La3+, Y3 +, Er3+, Ce3+ and sodium alginate M/G≈1 was between 32 and 41 N, the Young’s modulus was between 14 and 20 N, the elasticity was between 55% and 59%, the equilibrium water content was greater than 93%, the strength of the four gel was Ce3+> Er3+> Y3+> La3+, the elasticity was Ce3+1, the affinity of seaweed rare earth gel was in this order：Er3+>Ce3+>Y3+>La3+. When M/G=0.99≈1 and M/G=0.19 Er3+> Y3+> La3+. Among them, Ce3+, Y3+ and La3+ had a certain preference for G fragment of sodium alginate, and Er3+ had a certain preference for M fragment. This study would lay a theoretical foundation for the intensive processing and utilization of sodium alginate and the development of new functional materials of rare earth elements.

Protein gelation can provide texture in plant-based foods and can be influenced by many factors, including protein extraction method and salt addition. However, the protein gelation mechanism is still not well understood for plant proteins, especially for isolates obtained using commercial protein extraction processes. Therefore, the structural changes that legume sources such as yellow pea, faba bean, and soybeans undergo during the gelation process to understand the differences in their gelation mechanisms was investigated herein by using small-angle neutron scattering. Among these protein sources, the commercial extraction method was found to play a major part in the gelation pathway. Intensive protein extraction methods involving isoelectric precipitation led to lower protein solubility (∼1–38% w/w), larger insoluble protein particle sizes (60–100 μm), and a gelation pathway that is dependent on the changes of the insoluble protein particles. In contrast, extraction using ultrafiltration instead of precipitation resulted in higher protein solubility (∼18–88% w/w) and smaller insoluble protein particle sizes (40–70 μm), and the structural changes observed during gelation involved the structural changes of both soluble proteins and insoluble proteins. SEM imaging also showed different gel networks, with fractal networks formed by insoluble proteins (for sources with low solubility) or more homogenous networks formed by the interactions between the soluble proteins (for sources with high solubility). Despite the differences observed in the gelation network and the protein solubility, the gelation strength exhibited by protein sources at low protein solubility were similar to the ones by protein sources at high protein solubility, demonstrating the potential of fractal gel networks in providing texture. [Display omitted] • Protein structural changes are dependent on solvent pH and salt content. • Different gel network structures can exhibit similar gel strengths. • Less soluble protein sources form gel networks with insoluble protein particles. • More soluble protein sources form a homogeneous network around insoluble particles. [ABSTRACT FROM AUTHOR]

Natural polysaccharide sources have attracted widespread attention in the food, medical and beauty industries because of their range of biological activities. To investigate the gel functional properties and underlying mechanisms of the interaction between Dendrobium officinale polysaccharide (DOP) and κ-carrageenan (KC), a comprehensive analysis was conducted using various instruments, such as rheometers, texture analysers, scanning electron microscopes, and Fourier transform infrared spectroscopy. When the ratio of NK/ND (DK) was 1:1, the gel strength, water-holding capacity, swelling capacity, freeze‒thaw stability, and moisturizing properties were improved compared with those of NK and ND. Moreover, the sol‒gel transition temperature decreased after the combined use of NK and ND, indicating better flexibility and moisturizing properties. Additionally, the addition of the hydrogen bond breaker urea significantly decreased the storage modulus (G′) of the gel, whereas the addition of an electrostatic force breaker increased the G′ value, highlighting the crucial roles of hydrogen bonds and electrostatic forces in its gel network formation. Furthermore, the addition of glucuronic acid demonstrated that the carboxyl groups on the DK chains are involved in maintaining the formation of inter- and intra-hydrogen bonds in the DK gel network. Moreover, the molecular docking results revealed hydrogen bonding interactions between NK and ND, which are combined through helical twisting. In summary, DK achieves synergy through physical cross-linking, and its excellent water-holding, moisturizing, and adhesive properties suggest its potential as a wound dressing. [Display omitted] • DOP and KC form gel with improved gel quality by synergistic interaction. • DOP intersperse among fibrous structures of KC to obtain an ordered system. • Synergistic effect is due to hydrogen bonding formation between two polysaccharides. • DOP filled between KC acts as a powerful scaffold to provided support for the gel. [ABSTRACT FROM AUTHOR]

Highlights Metal–organic frameworks (MOFs) are used to directly initiate the gelation of graphene oxide (GO), producing MOF/rGO aerogels. The ultralight magnetic and dielectric aerogels show remarkable microwave absorption performance with ultralow filling contents. Abstract The development of a convenient methodology for synthesizing the hierarchically porous aerogels comprising metal–organic frameworks (MOFs) and graphene oxide (GO) building blocks that exhibit an ultralow density and uniformly distributed MOFs on GO sheets is important for various applications. Herein, we report a facile route for synthesizing MOF/reduced GO (rGO) aerogels based on the gelation of GO, which is directly initiated using MOF crystals. Free metal ions exposed on the surface of MIL-88A nanorods act as linkers that bind GO nanosheets to a three-dimensional porous network via metal–oxygen covalent or electrostatic interactions. The MOF/rGO-derived magnetic and dielectric aerogels Fe3O4@C/rGO and Ni-doped Fe3O4@C/rGO show notable microwave absorption (MA) performance, simultaneously achieving strong absorption and broad bandwidth at low thickness of 2.5 (− 58.1 dB and 6.48 GHz) and 2.8 mm (− 46.2 dB and 7.92 GHz) with ultralow filling contents of 0.7 and 0.6 wt%, respectively. The microwave attenuation ability of the prepared aerogels is further confirmed via a radar cross-sectional simulation, which is attributed to the synergistic effects of their hierarchically porous structures and heterointerface engineering. This work provides an effective pathway for fabricating hierarchically porous MOF/rGO hybrid aerogels and offers magnetic and dielectric aerogels for ultralight MA.

The aim of this study was to evaluate the effect of oat β-glucan on the formation mechanism, microstructure and physicochemical properties of konjac glucomannan (KGM) composite hydrogel. The dynamic rheology results suggested that the addition of oat β-glucan increased the viscoelastic modulus of the composite hydrogel, which was conducive to the formation of a stronger gel network. Gelling force experiments showed that hydrogen bonds and hydrophobic interactions participated in the formation of the gel network. Textural profile analysis results found that the amount of oat β-glucan was positively correlated with the elasticity, cohesiveness and chewiness of the composite hydrogel. The water-holding capacity of the composite hydrogel was enhanced significantly after the addition of oat β-glucan (p < 0.05), which was 18.3 times that of the KGM gel. The thermal stability of KGM gel was enhanced after the addition of oat β-glucan with the increase in Tmax being approximately 30 °C. Consequently, a composite hydrogel based on KGM and oat β-glucan was a strategy to overcome pure KGM gel shortcomings. [ABSTRACT FROM AUTHOR]

Highlights: Metal–organic frameworks (MOFs) are used to directly initiate the gelation of graphene oxide (GO), producing MOF/rGO aerogels. The ultralight magnetic and dielectric aerogels show remarkable microwave absorption performance with ultralow filling contents. The development of a convenient methodology for synthesizing the hierarchically porous aerogels comprising metal–organic frameworks (MOFs) and graphene oxide (GO) building blocks that exhibit an ultralow density and uniformly distributed MOFs on GO sheets is important for various applications. Herein, we report a facile route for synthesizing MOF/reduced GO (rGO) aerogels based on the gelation of GO, which is directly initiated using MOF crystals. Free metal ions exposed on the surface of MIL-88A nanorods act as linkers that bind GO nanosheets to a three-dimensional porous network via metal–oxygen covalent or electrostatic interactions. The MOF/rGO-derived magnetic and dielectric aerogels Fe3O4@C/rGO and Ni-doped Fe3O4@C/rGO show notable microwave absorption (MA) performance, simultaneously achieving strong absorption and broad bandwidth at low thickness of 2.5 (− 58.1 dB and 6.48 GHz) and 2.8 mm (− 46.2 dB and 7.92 GHz) with ultralow filling contents of 0.7 and 0.6 wt%, respectively. The microwave attenuation ability of the prepared aerogels is further confirmed via a radar cross-sectional simulation, which is attributed to the synergistic effects of their hierarchically porous structures and heterointerface engineering. This work provides an effective pathway for fabricating hierarchically porous MOF/rGO hybrid aerogels and offers magnetic and dielectric aerogels for ultralight MA. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the chemical composition, molecular weight (Mw), and monosaccharide composition of Premna microphylla Turcz polysaccharide (PMP) and revealed the effects of calcium ions (Ca2+) on the rheological properties, thermal stability, texture properties, and structural properties of PMP gels. Additionally, the gelation mechanism of PMP was proposed. The results revealed that PMP was a negative charge acidic polysaccharide primarily composed of glucose, galactose and rhamnose. The results of small and large amplitude oscillatory shear experiments illustrated that the storage modulus (G′), loss modulus (G″), relaxation modulus (G(t)) of PMP gels showed a positive correlation with Ca2+ concentration, indicating the addition of Ca2+ improved the viscoelasticity and shear thinning capacity of PMP gels. Furthermore, the gel strength, hardness, and thermal stability of PMP gels were enhanced with increase of Ca2+ concentration. The microstructure of PMP gel was changed obviously after adding Ca2+, generating the lamellar and lump-like structure due to the PMP aggregation. The results of Zeta potential, X-ray diffraction, and Fourier transform infrared spectroscopy (FT-IR) analysis indicated that electrostatic interactions played a crucial role in the formation of PMP gel and three-dimensional structure. These results suggested that PMP had great potential for application in the food industry due to their excellent gelation properties. [Display omitted] [ABSTRACT FROM AUTHOR]

To expand the applicability of gel fracturing fluids in ultra-high-temperature reservoirs, a temperature-resistant polymer was synthesized using the solution polymerization method. Subsequently, an ultra-high-temperature-resistant polymer gel was formulated by incorporating an organic zirconium crosslinking agent. A comprehensive investigation was carried out to systematically study and evaluate the steady shear property, dynamic viscoelasticity, and temperature and shear resistance performance, as well as the core damage characteristics of the polymer gel. The obtained results demonstrate that the viscosity remained at 147 mPa·s at a temperature of 200 °C with a shear rate of 170 s−1. Compared with the significant 30.9% average core damage rate observed in the guanidine gum fracturing fluid, the core damage attributed to the polymer gel was substantially mitigated, measuring only 16.6%. Finally, the gelation mechanism of the polymer gel was scrutinized in conjunction with microscopic morphology analysis. We expect that this study will not only contribute to the effective development of deep and ultradeep oil and gas reservoirs but also furnish a theoretical foundation for practical field applications.

Surimi gels are highly valued by consumers owing to their rich nutrients, distinctive flavor, and easily adjustable gel texture. Typically, 2%–3% salt is added to achieve optimal gel characteristics during surimi processing. However, excessive salt intake poses substantial health risks. Consequently, the urgent need to reduce the salt content in surimi gels is a new trend in the current food industry development. This study provides a comprehensive overview of the gelatinization mechanism of myosin. In addition, it explores the principles of salt-reduction techniques for modulating myosin gelation behavior, highlighting their limitations and their prepared quality characteristics of reduced-salt surimi gels. Moreover, the future prospects of reduced-salt surimi gels are discussed in relation to their functional properties. The gel formation mechanism of surimi has two critical steps: initial myosin solubilization and heat treatment. However, low-salt conditions restrict myosin solubilization, hindering the formation of high-quality gels. Recently, emerging processing technologies have gained considerable attention for their ability to modify protein interactions, becoming a focal point in salt-reduction research. In addition to their food applications, reduced-salt surimi gels have considerable potential for use in the medical and healthcare sectors. Utilizing three-dimensional (3D) printing technology, special functional reduced-salt surimi gel products can be designed, allowing personalized and precise nutrition delivery. The ultimate goal was to achieve the widespread production of high value–added surimi gel products. • The gelation mechanism of myosin and its influencing factors are listed in detail. • The assembly behavior of myosin is related to salt concentration and heating temperature. • Salt-reduction mechanisms of surimi gels under different processing methods are summarized. • Enhancing reduced-salt surimi for health products faces ongoing challenges. [ABSTRACT FROM AUTHOR]

A novel fire-preventing composite gel, mainly made from steel slag (SS) and silica fume (SF), was created for a coal mine's spontaneous combustion. The gelation mechanism of the steel slag-based composite gel (SSG) was investigated using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and field emission scanning electron microscopy (SEM). The findings suggest that SSG is generated through the processes of hydration and geopolymerization involving SS and SF. And in the alkaline milieu of a 1.5 M water glass solution, SSG manifests enhanced strength and water retention capacities. Moreover, the fire prevention and extinguishing performance of the SSG was analyzed and verified using low-temperature oxidation, thermogravimetry, and low temperature nitrogen adsorption experiment (LTNA). The SSG has proven highly effective in suppressing spontaneous coal combustion by inhibiting CO production, raising the coal oxidation temperature, and reducing the contact area between oxygen and the coal body. [ABSTRACT FROM AUTHOR]

Pectins are acidic hetero-polysaccharides present in plant primary cell walls. With strong and interesting gelation capacity, some plant-sourced pectins including Nicandra physalodes (Linn.) Gaertn. pectin (NPGP) , Premna microphylla turcz pectin (PMTP) , and creeping fig pectin (CFP), have been traditionally used in making gel foods in China. However, little is known about their gelation behaviors and the mechanisms involved. In this review, the extraction, structures , gelation behaviors and the underlying mechanisms of NPGP, PMTP and CFP are introduced. Moreover, the structure-property relation of major pectin types (i.e. commercial citrus and apple pectins) is also summarized for providing a deep understanding on pectin gelation. Both the intrinsic pectin structures and extrinsic environmental factors significantly affect the gelation of pectins. The interplay between these factors is also important, which sometimes can impart pectins with unexpected gelation behaviors. For NPGP , PMTP and CFP, all of them possess a relatively high galacturonic acid (GalA) content and a very low DM value, which allow them to behave like the typical "polyelectrolytes" and make them highly sensitive to the presence of cations. Monovalent cations (e.g. Na+ and/or H+) are able to induce the gelation of these pectins at appropriate conditions. Besides, NPGP , PMTP, and CFP can also form Ca2+-induced gels at ambient temperature with a moderate gelling rate, which is rarely reported for citrus and apple pectins. The underlying mechanism is still unclear at this moment. Therefore, the structure-property relation on pectin gelation needs to be further explored. • Some plant-sourced low methoxyl pectins can gel in the absence of calcium ions. • Synergism can be adopted to enhance the rheological and gelling ability of pectins. • Spontaneous gelation was found to occur for creeping fig pectins. • These plant-sourced pectins can form Ca2+-induced gels at room temperature. • The understanding on the structure-property relation of pectins is still insufficient. [ABSTRACT FROM AUTHOR]

Silk fibroin hydrogel not only has biocompatibility, but also has environmental response ability. It plays an important role in the development of material. The gelation mechanism of silk fibroin hydrogel is very important to textile and medicine fields. The molecular dynamics simulation was used to discuss the structure and non-bond interaction of silk fibroin hydrogel. The results show that the non-bond interactions between silk fibroin molecules and water molecules have certain influence on the formation of silk fibroin hydrogel. According to the hydrogen bond analysis, the hydrogen bonds are mainly formed between random coil peptide fragments at the two ends of silk fibroin molecules and residues 252-254 are the key residues. The electrostatic and polar solvation interactions between silk fibroin molecules plays a major role in cross-linking of the coil segments of two silk fibroin molecules.

The object of research is natural polysaccharides. One of the problems is the high cost and not always environmental friendliness of foreign analogues of these substances. Therefore, the methods of purification of polydisperse systems with the help of dispersed minerals, in particular separated dispersed mineral glauconite, purified and enriched up to 60 % of the initial content, are proposed. The study used aqueous solutions of dextran and pectin, which added glauconite in the amount of 0.3 to 0.9 % by weight of the solution, heated to 60 °C and kept for 10 minutes. Using glauconite in the amount of 0.3 % by weight of the solution gave high quality indicators. Thus, the dependence of the viscosity of polysaccharides dextran and pectin on the concentration of the introduced mineral was studied. The lowest value of viscosity is observed when adding 0.3 % glauconite to the mass of the solution, with increasing concentration, the viscosity increases. The process of interaction of dextran molecules with the surface of glauconite is due to the fact that the proposed method of studying the viscosity has a feature that connects neighboring mineral particles through the dextran bridge and the formation of a stable gel structure. These structures are manifested in the form of partial groups of glauconite. This provides the ability to obtain such an indicator as adsorption. The mechanism of interaction of dextran with glauconite is confirmed by the dependence of the amount of dextran adsorbed on the surface of the mineral. Thus, at low concentrations of glauconite – up to 0.3 % adsorption of dextran on the surface increases, and with increasing concentration of glauconite – greatly decreases. This is crucial for the technological parameters of the mineral when using it in preparation processes, in comparison with similar adsorbents of unnatural origin. This will provide the benefits of glauconite over the use in the food industry and the regulation of the physicochemical properties of industrial polydisperse solutions as inexpensive additives of natural origin (stabilizers, thickeners, etc.) that are harmless to human health. [ABSTRACT FROM AUTHOR]

So far, it has been difficult to directly compare diverse characteristic gelation mechanisms over different length and time scales. This paper presents a universal water structure analysis of several gels with different structures and gelation mechanisms including polymer gels, supramolecular gels composed of surfactant micelles, and cement gels. The spatial distribution of water molecules was analyzed at molecular level from a diagram of the relaxation times and their distribution parameters (τ–β diagrams) with our database of the 10 GHz process for a variety of aqueous systems. Polymer gels with volume phase transition showed a small decrease in the fractal dimension of the hydrogen bond network (HBN) with gelation. In supramolecular gels with rod micelle precursor with amphipathic molecules, both the elongation of the micelles and their cross-linking caused a reduction in the fractal dimension. Such a reduction was also found in cement gels. These results suggest that the HBN inevitably breaks at each length scale with relative increase in steric hindrance due to cross-linking, resulting in the fragmentation of collective structures of water molecules. The universal analysis using τ–β diagrams presented here has broad applicability as a method to characterize diverse gel structures and evaluate gelation processes.

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Konjac glucomannan (KGM) is a functional polysaccharide isolated from the tubers of Amorphophallus konjac C. Koch known for its superior heat-set gel-forming capacity. Although commonly used for decades in food industry, KGM's unique gelling behavior has drawn lots of attention in recent years, and it also presents significant challenges especially when elucidating its gelation mechanism. In this review, recent progress and developments on gelation mechanism of the alkali induced heat-set KGM gel have been summarized on many key topics, including the experimental techniques, differences between gel preparation routes, and most importantly, correlating morphological/structural features and intermolecular interactions during the gelling process. In addition, impacts of internal and external factors on the KGM gelation, especially the mechanically related properties, have been also discussed. The understanding of KGM gelation has been evolving over the last decade. The possible gelation includes the deacetylation induced by alkali addition, the stretch and physically association of chains upon heat-treatment, and the three-dimensional gel network established on the agglomeration of random network. Although insights have been provided into the gelation mechanism of KGM in this review which uncovers the foundational aspects of structure/property relationships in terms of KGM gel. There are still unanswered questions and areas, in particular the alkali and heat-treatment induced intermolecular association mechanism, where further research employing some state-of-the-art in situ characterization techniques as well as computation models is required. [Display omitted] • Gelation mechanism of alkali-induced heat-set KGM gel is updated. • Changes in gel morphology and structure across the time scale are discussed. • Factors including KGM concentration and temperature can strongly affect the gel formation and property. • Impact of swelling on alkali induced heat-set KGM gels is yet to be illustrated. • The underlying mechanism of heat-treatment induced intermolecular association remains unknown. [ABSTRACT FROM AUTHOR]

Mung bean protein isolate (MBPI) has attracted much attention as an emerging plant protein. However, its application was limited by the poor gelling characteristics. Thus, the effect of sanxan (SAN) on the gelling behavior of MBPI under microbial transglutaminase (MTG)-induced condition were explored in this study. The results demonstrated that SAN remarkably enhanced the storage modulus, water-holding capacity and mechanical strength. Furthermore, SAN changed the microstructure of MBPI gels to become more dense and ordered. The results of zeta potential indicated the electrostatic interactions existed between SAN and MBPI. The incorporation of SAN altered the secondary structure and molecular conformation of MBPI, and hydrophobic interactions and hydrogen bonding were necessary to maintain the network structure. Additionally, in vitro digestion simulation results exhibited that SAN remarkably improved the capability of MBPI gels to deliver bioactive substances. These findings provided a practical strategy to use natural SAN to improve legume protein gels. [Display omitted] • SAN could enhance the overall structure of MBPI gels. • SAN interacted with MBPI mainly via hydrophobic interaction and hydrogen bond. • Simultaneous covalent and non-covalent interactions in MBPI-SAN composite gel. • MBPI-SAN composite gel had a more compact and uniform microstructure. • MBPI-SAN composite gel showed effective protection against Cur by in vitro digestion. [ABSTRACT FROM AUTHOR]

A novel and simple gelling system based on a water-soluble copolymer of isobutylene and maleic anhydride (commercial name, Isobam) was adopted to manufacture various ceramics via spontaneous gelation. The gelation mechanism of AlN slurry was investigated using infrared spectroscopy. Results show that Isobam was hydrolyzed to produce the –COOH group, and the hydrogen bonding was formed between the –COOH and –CONH 2 groups of Isobam during spontaneous gelation. Meanwhile, the gelling process of the Isobam system could be accelerated via enhancing hydrogen bonding through APS addition. With 1 wt% addition of APS, the gelation time reduced to 23 h, the viscosity of 50 vol% AlN slurry decreased to 0.21 Pa·s, and the flexural strength of green body improved by 48%. Therefore, the presence of hydrogen bonding in the Isobam gelation mechanism was confirmed, and it could be enhanced by introducing APS to accelerate gelation. [ABSTRACT FROM AUTHOR]

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Copyright of Journal of China University of Petroleum is the property of China University of Petroleum and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

• Self-assembled heat-induced gels had higher mechanical strength. • Hydrophobic interactions had a greater role in self-assembled heat-induced gels. • Self-assembled cold-induced gels had better water retention and dense structure. • Whether or not heat treatment is used to form gels may play a more important role. • Self-assembled cold-induced gels could effectively load bioactive substances. Based on the findings of our previous studies, a comprehensive comparative investigation of the quality and formation mechanism of gels obtained from protein self-assemblies induced by different methods is necessary. Self-assembled heat-induced gels had higher gel mechanical strength, and hydrophobic interactions played a greater role. Whether or not heat treatment was used to induce gel formation may play a more important role than the effect of divalent cations on gel formation. Hydrogen bonds played an important role in all gels formed using different gelation methods. Furthermore, Self-assembled cold-induced gels were considered to can load bioactive substances with different hydrophilicity properties due to the high water-holding capacity and the smooth, dense microstructure. Therefore, β-lactoglobulin fibrous and worm-like self-assembled cold-induced gels as a delivery material for hydrophilic bioactive substances (epigallocatechin gallate, vitamin B 2) and amphiphilic bioactive substance (naringenin), with good encapsulation efficiency (91.92 %, 97.08 %, 96.72 %, 96.52 %, 98.94 %, 97.41 %, respectively) and slow-release performance. [ABSTRACT FROM AUTHOR]