Gelation Agent Research Articles

Physicochemical properties, the digestible and resistant starch content of chestnut flour with different particle sizes

Abstract In this study, chestnuts were processed into flour, and the obtained chestnut flour (CF) was passed through a sieve with an aperture size of 212 µm. Then the physicochemical properties, digestible and resistant starch contents of CF1 (<212 µm), CF2 (≥212 µm), and commercial chestnut flour (CCF) were determined. It was found that CCF had the highest values in terms of proximate composition, total soluble polyphenol content (891.25 mg GAE/100 g), and antioxidant activity (ABTS: 1552.11 mg TE/100 g, DPPH: 2003.01 mg TE/100 g). On the other hand, CF1 was superior in terms of resistant starch content (39.31 g/100 g, dw) (p < 0.05). The resistant starch content of CF1 was approximately 1.5-fold and 3-fold higher than CCF and CF2, respectively. Furthermore, the rapidly digestible starch content of CF1 (2.1 g/100 g, dw) and CF2 (0.93 g/100 g, dw) was quite lower than CCF (12.64 g/100 g, dw) (p < 0.05). Moreover, CF1 exhibited lower (p < 0.05) water, alkaline water, and sodium carbonate retention capacities, which make it a potential good flour for cookie and cracker production. In contrast, CF2 could be evaluated as a good ingredient for noodle-type foods due to its lower water solubility index. Considering the least gelation concentrations of samples, it was seen that CF1 (% 10) could also be valorized as a thickening or gelation agent in the food industry, as well as CCF (% 6).

Design and experimental study on rheological behavior and sealing performance of shear sensitive fluids to control lost circulation during drilling

Loss circulation is considered as a time-consuming, costly, and challenging issue while drilling or cementing jobs, which ought to be treated and resolved promptly. The choice of a treatment that quickly plugs the loss zone and helps to restore the circulation is critical. Cross-linkable polymer gels play a significant role in mitigating drilling fluid loss, but controlling the gelation time and pumpability are the main challenges of these gels. This research aims to evaluate a novel smart fluid that has high flexibility in design. The shear sensitive fluid (SSF) is an oil-based fluid containing a polymer, gelation agents, and multi-crosslinkers. After passing through the drilling bit, the SSF is crosslinked with time to produce a high strength gel. The designed shear sensitive fluid is one of the possible solutions for severe loss circulation.The overall purpose of this research was to scrutinize the gelation behavior and SSF performance as a smart lost circulation treatment, which was followed in two sections including experimental analysis and empirical modeling. The effect of various factors including the type of crosslinker, shear rate, emulsifier concentration, temperature, shear history, salinity, etc. on the performance of the formed gels was studied. Furthermore, the maximum sealing pressure of formed gels in the highly permeable porous medium and fractured core as well as the probability of formation damage was evaluated.In order to determine the correlations required to predict the ultimate gelation time of SSF, the response surface methodology was utilized according to the central composite design. The considerable values of correlation coefficients (R2 = 0.91) prove the validity of estimated models for the fit enough responses with the experimental data. For the designed SSFs, depending on the operating conditions, the appropriate gelation time can be adjusted by emulsifier concentration and shear rate values. Also, the minimum gelation time and the highest crosslinking rate occur approximately at the shear rate of 45,000 1/s. At high shear rates, the effect of temperature on the functionality of the formed gels decreases, which is due to the high rate of crosslinking. Based on dynamic sealing pressure tests, the SSFs have a high potential in mitigation of lost circulation during drilling. The maximum sealing pressure was measured above 1000 psi in highly permeable porous medium and up to 600 psi in fractured core, which indicate the high strength of the formed gels against drilling fluid pressure. The designed SSFs could be easily removed from reservoir by 15 vol% hydrochloric acid, indicating the non-damaging properties of the formed gels.

Cereal β-d-Glucans in Food Processing Applications and Nanotechnology Research

Cereal (1,3)(1,4)-β-d-glucans, known as β-d-glucans, are cell wall polysaccharides observed in selected plants of grasses, and oats and barley are their good natural sources. Thanks to their physicochemical properties β-d-glucans have therapeutic and nutritional potential and a specific place for their functional characteristics in diverse food formulations. They can function as thickeners, stabilizers, emulsifiers, and textural and gelation agents in beverages, bakery, meat, and extruded products. The objective of this review is to describe the primary procedures for the production of β-d-glucans from cereal grains, to define the processing factors influencing their properties, and to summarize their current use in the production of novel cereal-based foods. Additionally, the study delves into the utilization of β-d-glucans in the rapidly evolving field of nanotechnology, exploring potential applications within this technological realm.

The Effect of the Gelling Agent on the Gelation Rate and the Formed Sol-Gel Structure

In this paper a combination of colloidal silica and different gelling agents are studied in order to observe the effect of gelation rate on the formed sol-gel structure. Proper ratios of sol matrix materials and gelation agents were determined. Sets of samples based on these recipes were prepared with added filling material and tested for mechanical properties. Samples with added solution of NaCl gelling agent showed the highest flexural strength observed and also lower doses of this gelling agent are required for one of the studied sols which can positively effect the final price of product.

Fabrication and Properties of Highly Porous Ceramics via Gel Casting Using Steel Slag as a Novel Gelation Agent

Fabrication and Properties of Highly Porous Ceramics via Gel Casting Using Steel Slag as a Novel Gelation Agent

Formation of hen egg white lysozyme derived amyloid-based hydrogels using different gelation agents: A potential tool for drug delivery

Amyloids are highly stable protein fibrillar aggregates that get deposited in various parts of our body and cause detrimental diseases. But in nature, the presence of functional amyloids is also noted in bacteria that help them by forming hyphae, biofilm, protein reservoirs, signalling messengers, etc. Keeping this perspective in mind, the idea behind this research was to develop functional amyloids in the form of hydrogel and analyse its potential in the biomedical sector as a drug-delivery tool. The synthesis and characterisation of three types of amyloid-based hydrogels have been reported in this work. Hen Egg-White Lysozyme (HEWL) protein was chosen as the principal ingredient as it is extensively used as a standard protein for studying amyloidogenesis and has inherent antibacterial properties. Comparative studies of different hydrogel properties exhibited variations in the hydrogels based on compositional differences in them. Finally, a drug release assay was done on the synthesized hydrogels to explore their potential as drug delivery tools.

Research on the gel casting process and flexural strength of high-stability alumina ceramics

Gel casting is an advanced wet-forming method for ceramics. In this paper, Isoabm 104 is selected as the dispersant and gelation agent for gel casting. The optimization of gel casting slurry and the preparation of the green and sintered alumina bodies are investigated. TAC reduces the viscosity of the slurry significantly due to electrostatic interaction. Isopropanol alcohol and vacuum tank eliminates the slurry’s air bubbles, thus improving the density of green bodies. A staged drying process is necessary to produce smooth and defect-free green bodies. After optimization of the slurry formulation and gel casting process, alumina ceramics with a Weibull modulus of 11.1 are successfully prepared.

Crystalline Magnetic Gels and Aerogels Combining Large Surface Areas and Magnetic Moments.

The production of materials that simultaneously combine large surface areas and high crystallinities is a major challenge. Conventional sol-gel chemistry strategies to produce high-surface-area gels and aerogels generally result in amorphous or poorly crystalline materials. To attain proper crystallinities, materials are exposed to relatively high annealing temperatures that result in significant surface losses. This is a particularly limiting issue in the production of high-surface-area magnetic aerogels owing to the strong relationship between crystallinity and magnetic moment. To overcome this limitation, we demonstrate here the gelation of preformed magnetic crystalline nanodomains to produce magnetic aerogels with high surface area, crystallinity, and magnetic moment. To exemplify this strategy, we use colloidal maghemite nanocrystals as gel building blocks and an epoxide group as the gelation agent. After drying from supercritical CO2, aerogels show surface areas close to 200 m2 g-1 and a well-defined maghemite crystal structure that provides saturation magnetizations close to 60 emu g-1. For comparison, the gelation of hydrated iron chloride with propylene oxide provides amorphous iron oxide gels with slightly larger surface areas, 225 m2 g-1, but very low magnetization, below 2 emu g-1. Thermal treatment at 400 °C is necessary to crystallize the material, which results in a surface area loss down to 87 m2 g-1, well below the values obtained from the nanocrystal building blocks.

Morphological Control Over Gel Structures of Mixed Semiconductor-Metal Nanoparticle Gel Networks with Multivalent Cations.

In this work, the influence of two different types of cations on the gel formation and structure of mixed gel networks comprised of semiconductor (namely CdSe/CdS nanorods NR) and Au nanoparticles (NP) as well as on the respective monocomponent gels is investigated. Heteroassemblies built from colloidal building blocks are usually prepared by ligand removal or cross-linking, thus, both the surface chemistry and the destabilising agent play an essential role in the gelation process. Due to the diversity of the composition, morphology, and optical properties of the nanoparticles, a versatile route to fabricate functional heteroassemblies is of great demand. In the present work, the optics, morphology, and gelation mechanism of pure semiconductor and noble metal as well as their mixed nanoparticle gel networks are revealed. The influence of the gelation agents (bivalent and trivalent cations) on the structure-property correlation is elucidated by photoluminescence, X-ray photoelectron spectroscopy, and electron microscopy measurements. The selection of cations drastically influences the nano- and microstructure of the prepared gel network structures driven by the affinity of the cations to the ligands and the nanoparticle surface. This gelation technique provides a new platform to control the formation of porous assemblies based on semiconductor and metalnanoparticles.

Gelation-based feed-stock technologies for HVOF thermal spray development: Micro-composite powder preparation and HVOF coating microstructure

The current study proposes use of the polysaccharide, sodium alginate, as a gelation aid to ‘solidify’ aqueous suspensions, comprised of micron-sized ceramic-metal particles, into spherical, micro-composite ‘cermet’ feedstock powders. These feedstock powders, with finely divided ceramic and metallic components, can then be used for the preparation of high velocity oxygen fuel coatings and/or laser deposition cladding. Sodium alginate gelation is typically based on ion exchange, and a variety of gelation agents have been examined in the present work. It is shown that aqueous solutions of CaCl2, Ca-acetate, Al-nitrate, methanol, acetic acid, and 5 % HCl acid are all capable of gelling alginate droplets through a simple cross-linking mechanism. Consequently, spraying a sodium alginate containing ceramic-metal particle suspension, with a suitable air atomising nozzle, into an aqueous bath of one of the outlined solutions allows the production of nominally spherical ‘cermet’ feedstock particles. In the present work, TiC-Ni3Al micro-composite cermet particles have been successfully produced, and then analysed both before and after a sintering heat-treatment. Furthermore, rheological assessment of the colloidal suspensions both prior to and during the gelling stage are also described. As a preliminary ‘proof-of-principle’, an initial set of HVOF coatings has also been prepared using the gelled feedstock material, and initial characterisation of these coatings is presented.

Effects of drying conditions on physicochemical properties of epoxide sol−gel derived α-Fe2O3 and NiO: A comparison between xerogels and aerogels

A simple and easily operated supercritical CO2 dryer was designed and manufactured with the aim of producing high-surface-area mesoporous α-Fe2O3 (hematite) and NiO aerogels. The gels were synthesized by a sol−gel method with the aid of propylene oxide (PO), as the gelation agent, and then dried and calcined at different conditions. The effects of drying and calcination conditions on the physicochemical properties of the final aerogels were investigated using X-ray diffraction (XRD), N2 adsorption-desorption, Fourier-transformed infrared spectroscopy (FT-IR), and field emission scanning electron microscopy (FE-SEM) analyses. It was demonstrated that α-Fe2O3 and NiO aerogels with high surface areas and mesoporosities could be successfully synthesized using the home-made supercritical CO2 dryer. Supercritical drying of the gels resulted in α-Fe2O3 (186 m2/g) and NiO (178 m2/g) aerogels with 186% and 34% higher surface areas, respectively, than xerogels obtained via simple drying at 80°C using a laboratory oven. In addition, the results showed that supercritical CO2 drying could enhance preservation of the porous network of the oxide nanostructures at high calcination temperatures via suppression of sintering phenomenon. Calcination of α-Fe2O3 and NiO aerogels at 600°C yielded 225% and 53% higher surface areas than the corresponding xerogel, confirming the significance of drying step in the sol−gel method. Asphaltene adsorption from a model oil with asphaltene concentration of 3000 ppm indicated that the aerogels possessed higher adsorption capacities for the bulky asphaltene molecules than xerogels calcined at the same temperature of 600°C, which was due to their enhanced textural properties.

Studying the Role of Gelation Agents in Gelcasting Non-porous Si3N4 Bodies by Pressureless Sintering

Studying the Role of Gelation Agents in Gelcasting Non-porous Si3N4 Bodies by Pressureless Sintering

Ultralight MOF-Derived Ni3S2@N, S-Codoped Graphene Aerogels for High-Performance Microwave Absorption.

To develop high-performance microwave absorption materials with the features of lightweight, thin thickness, broad bandwidth, and strong absorption, an ultralight Ni3S2@N, S-codoped graphene aerogel with a density of 13.5 mg/cm3 has been fabricated by the use of metal-organic frameworks (MOFs) to directly initiate the gelation of graphene oxide strategy. In such a strategy, dual-functional 1D Ni-MOF nanorods not only act as the gelation agent but also afford the doping elements (N and S) originated from the organic species and the precursor for metal sulfide. Due to the synergistic effects of good impedance matching and multiple losses, the optimal reflection loss (RL) of as-prepared Ni3S2@N, S-codoped graphene aerogel reaches −46.9 dB at 17.1 GHz with only 2.0 mm and ultralow filling content (1.75 wt%). The maximum effective absorption bandwidth (EAB) reaches 6.3 GHz (11.7–18.0 GHz) at 2.38 mm, covering the whole Ku band. Moreover, the value of EAB with the RL less than −30 dB can be tuned to 12.2 GHz (5.8–18 GHz) at the absorber thickness ranging from 1.9 to 5.0 mm. This work provides insight for rational design and fabrication of multicomponent-containing graphene aerogels, showing the potential application in lightweight and high-performance microwave absorption.

Preparation and characterization of konjac glucomannan (KGM) and deacetylated KGM (Da-KGM) obtained by sonication.

Konjac glucomannan (KGM) has been widely applied in the food industry as a thickening and gelation agent because of its unique colloidal properties of viscosity enhancement and gelling ability. The current study aimed to prepare and characterize KGM and deacetylated KGM (Da-KGM) samples obtained by sonication in neutral and alkali ethanol-water solutions. The results showed that the deacetylation degree (DD) of Da-KGM increased exponentially with alkali concentration. Fourier transform infrared spectrometry further confirmed the deacetylation reaction through the dramatic decrease in the acetyl group band at 1740 cm-1 . Besides, the high similarity among the tested groups in terms of X-ray diffraction (XRD) spectra implied a similar crystalline structure, while differential scanning calorimetry (DSC) curves revealed that the water binding capacity and decomposition temperature of KGM changed slightly with alkali and sonication treatment. The rheological profiles indicated that apparent viscosity (η0 ) of sonicated KGM samples was unchanged except for the T60 group (60 min sonication treatment). Particularly, ultrasonic treatment under high alkaline conditions (0.10mol L-1 NaOH) was noted to promote the deacetylation reaction, and the obtained samples showed decreased apparent viscosity and weakened the gelation process in aqueous solution. Partial correction analysis indicated that alkali rather than ultrasonic treatment resulted in the change of DD and η0 in Da-KGM. Moreover, sonication contributed to off-white color by reducing the browning caused by alkali in Da-KGM products. Ultrasound-mediated heterogeneous deacetylation reaction is a feasible way to prepare Da-KGM samples with lightened browning and controllable DD. © 2022 Society of Chemical Industry.

Various colloid systems for drawing of aluminum oxide fibers

The aim of this study was to develop new low-cost synthesis routes to produce aluminum oxide ceramic fibers for high temperature insulation. The co-precipitation and sol gel chemistry provided the basic of the syntheses. The starting materials were varied from inorganic Al salts (nitrate and chloride) to organic Al compounds (acetate and isopropoxide). The influence of various chemical additives such as polymers, surfactants, basic and gelation agents has been determined on the fiber parameters. Important task was to find the appropriate and efficient fiber drawing technique and heat treatment. The solvent spinning technique has been proved to be an optimal device to produce fibers qualified for high temperature insulation. These fibers can be characterised by diameter of 10–20 μm and the length of 5–15 cm. The techniques as SEM, NMR spectroscopy, DLS, DTA, WAXS, the measurement of tensile strength, thermal conductivity, and heat resistance were aimed to characterise the fibers.

Preparation of fat substitute based on the high-methoxyl pectin of citrus and application in moon-cake skin

The high-methoxyl pectin of citrus was used to prepare a fat substitute and applied to the processing technology of moon-cake skin. The physical, chemical, and sensory properties of fat substitutes and prepared moon-cake skins were studied by selecting texture properties, rheological properties, water distribution, and water-holding capacity. Results showed that the gel hardness of glucan–sucrose (G-SG) (glucan/sucrose = 4:6) as synergistic gel was 6.23 ± 0.10 N, the elasticity was 3.97 ± 0.03 mm, the adhesive viscosity was 4.87 ± 0.20 N, the chewiness was 16.87 ± 0.51 mj, the water-holding capacity was 98.33%, and the gel obtained from sucrose (SG) as gelation agent had no significant difference (P > 0.05). The consistency coefficient and thixotropic circle area of G-SG was larger than that of SG. Through dynamic viscoelastic scanning, we found that the tanδ of G-SG was smaller, and it had stronger hydrophobic interaction and stronger fluid properties after high-speed shear. It also more easily maintained a flow state similar to oil. G-SG was further applied to the processing technology of low-fat moon-cake skin. The color of the prepared low-fat moon-cake skin darkened, the water-holding capacity was enhanced, the fat content decreased from 22.21% ± 0.54% to 14.07% ± 0.57%, the oil droplets enlarged, and flocculation strengthened. Results of texture-characteristic and sensory-score analyses showed no significant difference (P > 0.05) from the control group when the oil substitution amount was 40%. At this time, the total sensory score was 41.71 ± 2.02.

Electrochemical investigation of NiCo double hydroxides for supercapacitors

NiCo-layered double hydroxides (NCLDH) synthesized by a simple one pot sol–gel process using propylene oxide as gelation agent. Synthesized material is investigated for its crystal structure, morphology including specific surface area and electrochemical performance as supercapacitor electrodes. The specific capacitance of as-synthesized NCLDH is 1166F/g, when the electrodes undergone charge/discharge cycling in 6 M potassium hydroxide at 1 A/g specific current. Enthrallingly, retention of capacity over 1000 and 2000 cycles found up to correspondingly 80% and 64%, at relatively high 30 A/g specific current. High capacity is ascribed to uniform porous nature of the material with considerable surface area. With an appreciable cycle life and charge storage capacity, the material prepared is an able contender for supercapacitor electrodes.

Iron Encapsulation by Deacetylated Glucomannan as an Excipient Using the Gelation Method: Characteristics and Controlled Release.

SUMMARYResearch backgroundDeacetylation and the use of CaCl2 as a gelation agent improve the performance of glucomannan as iron encapsulant. This study was conducted to investigate the effects of deacetylation degree and pH of gelation on the characteristics of encapsulated iron using gelation in CaCl2 solution.Experimental approachGlucomannan was deacetylated at various NaOH concentrations and was subsequently utilized as an iron excipient using the pipette-dropped gelation method in CaCl2 solution to directly investigate the process of encapsulation by gelation. The pH of the gelation solution was also changed. The beads were subsequently vacuum-dried.Results and conclusionsDeacetylation led to lower endothermic peak of the glucomannan than that of the native one. The deacetylation degree and pH of gelation did not significantly affect the diameter of the beads but influenced their appearance and physical characteristics. The backbone of glucomannan was not changed by either the deacetylation degree or the pH of the gelation. The highest encapsulation efficiency (73.27%) was observed in the encapsulated iron using the glucomannan matrix of the highest deacetylation degree (82.56%) and gelated in the solution at pH=10. The highest deacetylation degree of glucomannan caused the highest swelling of the beads, which led to the release of a higher amount of iron. Glucomannan deacetylation improves the iron encapsulation and enables higher iron release at pH=6.8 than at pH=1.2. The Weibull model was the best-fitting model to represent the profile of iron release from the deacetylated glucomannan matrix using the gelation method (R2>0.93) at pH=6.8 and pH=1.2.Novelty and scientific contributionThis result supports the application of deacetylated glucomannan using NaOH as a pH-sensitive matrix for iron encapsulation and CaCl2 solution as gelation agent. A higher deacetylation degree leads to the release of a higher amount of iron from the matrix. The encapsulation does not only protect the iron but also delivers it to the absorption site and controls its release, which is useful in supplement formulation or food fortification. The results show that the deacetylated glucomannan as the matrix holds more iron in encapsulation process.

Konjac Glucomannan (KGM), Deacetylated KGM (Da-KGM), and Degraded KGM Derivatives: A Special Focus on Colloidal Nutrition.

Konjac flour, mainly obtained and purified from the tubers ofAmorphophallus konjac C. Koch, yields a high molecular weight (Mw) and viscous hydrocolloidal polysaccharide: konjac glucomannan (KGM). KGM has been widely applied in the food industry as a thickening and gelation agent as a result of its unique colloidal properties of effective viscosity enhancement and thermal-irreversible gelling. This review first narrates the typical commercial KGM source species, the industrial production, and the purification process of KGM flour. The structural information on native KGM, gelation mechanisms of alkali-induced deacetylated KGM (Da-KGM) hydrogel, progress on degraded KGM derivatives, cryoprotection effect, and colloidal nutrition are highlighted. Finally, the regulatory requirements of konjac flour and KGM among different countries are briefly introduced. The fine structure and physicochemical properties of KGM can be regulated in a great range via the deacetylation or degradation reaction. Here, the relationship between the physicochemical properties, such as viscosity, solubility, gelation, and nutritional effects, of native KGM, Da-KGM, and degraded KGM derivatives was preliminary established, which would provide theoretical guidance for designing KGM-based products with certain nutritional needs.

Genipin-crosslinked chitosan/alginate/alumina nanocomposite gels for 3D bioprinting

Immobilizing microorganisms inside 3D printed semi-permeable substrates can be desirable for biotechnological processes since it simplifies product separation and purification, reducing costs, and processing time. To this end, we developed a strategy for synthesizing a feedstock suitable for 3D bioprinting of mechanically rigid and insoluble materials with embedded living bacteria. The processing route is based on a highly particle-filled alumina/chitosan nanocomposite gel which is reinforced by (a) electrostatic interactions with alginate and (b) covalent binding between the chitosan molecules with the mild gelation agent genipin. To analyze network formation and material properties, we characterized the rheological properties and printability of the feedstock gel. Stability measurements showed that the genipin-crosslinked chitosan/alginate/alumina gels did not dissolve in PBS, NaOH, or HCl after 60 days of incubation. Alginate-containing gels also showed less swelling in water than gels without alginate. Furthermore, E. coli bacteria were embedded in the nanocomposites and we analyzed the influence of the individual bioink components as well as of the printing process on bacterial viability. Here, the addition of alginate was necessary to maintain the effective viability of the embedded bacteria, while samples without alginate showed no bacterial viability. The experimental results demonstrate the potential of this approach for producing macroscopic bioactive materials with complex 3D geometries as a platform for novel applications in bioprocessing.