Uniform Network Structure Research Articles

Fabrication, characterization, and fat substitution application in chocolate spreads of methyl cellulose and xanthan gum foam-templated oleogels.

Food-grade oleogels were prepared by lyophilizing the foam-template of methyl cellulose (MC) and xanthan gum (XG). The cryogels prepared using MC exhibited low density, high porosity and firmness, as well as high oil absorption capacity (OAC) and oil binding capacity (OBC). Furthermore, the addition of XG improved properties of cryogels. As the concentrations of MC and XG were incremented, notable enhancements in the cryogels' density and firmness were observed, accompanied by a corresponding decrease in porosity. Upon attaining MC concentration of 1.2 % and XG concentration of 0.3 %, the OBC of the cryogels surpassed 90 %. SEM images revealed that the cryogels possessed a dense and highly uniform porous network structure. Furthermore, oleogels formulated using the higher viscosity variant of MC (designated as MC3) exhibited greater firmness and apparent viscosity, resulting in the formation of a robust network structure that demonstrated excellent thermal stability. The incorporation of oleogels into chocolate spreads significantly enhanced textural and rheological characteristics, while simultaneously decreasing their enthalpy of crystallization. Notably, the partial substitution of these oleogels in the spreads yielded a crystalline morphology that was indistinguishable from those prepared solely with saturated fats, indicating a successful integration and preservation of desirable structural attributes.

Wax crystal dynamics and viscosity abnormal reduction in asphaltene-containing waxy oil at low temperatures

A micro-rheological integration experiment was conducted on model oils without asphaltene and with 0.05 wt% asphaltene. The study examined the viscosity-temperature characteristics of both model oils under different cooling rates and shear rates. Significant changes were observed in the viscosity-temperature curve of the asphaltene-containing model oil. At low shear rates, a distinct wavelet peak was identified in the temperature range of 37-30 °C, where viscosity initially increased, then decreased, and subsequently increased again. This wavelet peak diminished with the increasing shear rate, eventually forming a “buffer platform”. The underlying mechanism was attributed to asphaltene altering the wax crystal behavior from “uniform precipitation network structure formation” to “formation of unstable large aggregates - dissociation into multiple small stable aggregates - growth into larger stable aggregates.” In addition, the wax precipitation rate remained constant in the model oil without asphaltene, while in the asphaltene-containing model oil, the rate significantly accelerated between 34.5 °C and 32.5 °C. And the asphaltenes promoted the formation of small wax crystal particles but inhibited the growth of wax crystal particles.

Effect of ultrasound combined with highland barley dietary fiber on gel properties of reduced-salt chicken breast myofibrillar protein.

This study aimed to investigate the effect of ultrasound combined with highland barley dietary fiber (HBDF) on the quality of reduced-salt chicken breast myofibrillar protein (MP) gel. The molecular forces maintaining gel structure, the gelling formation process, and gel microstructure of different groups, two control groups (2% sodium chloride [NaCl] group, 1% NaCl group), and four treatment groups (0.3% HBDF+U5, 0.3% HBDF+U10, 0.5% HBDF+U5, and 0.5% HBDF+U10) were examined. Results indicated significant improvements (p<0.05) in gel properties such as water-holding capacity, textural characteristics, and color of the MP gel of the four treatment groups compared to Control 2 (1% NaCl) group. Furthermore, the second structural alterations were characterized by increase β-sheet, β-turn, and random coil structure contents in treatment groups, especially in 0.3% HBDF+U5 and 0.5% HBDF+U5 groups; in addition, the exposure of more hydrophobic groups and the formation of disulfide bonds and hydrogen bonds were promoted in treatment groups, thus enhancing protein aggregation and gel quality. Finally, compared to Control 2 (1% NaCl) group, more compact and uniform gel network structures and pores inside the composite gels were observed in treatment groups. In conclusion, the findings demonstrated that the application of ultrasound in combination with HBDF improved the gelling characteristics of reduced-salt chicken breast MP gel, especially 0.3% HBDF+U5 and 0.5% HBDF+U5 groups.

Effects of eggshell powder emulsion gel on the oxidative stability and sustained-release effect of lavender essential oil

This study aimed to develop a new type of eggshell powder (EP) emulsion gels for improving the antioxidant ability and sustained release effect of lavender essential oil (LEO). The effects of EP addition on the physicochemical, structural properties, oxidative stability, and sustained-release performance of the emulsion gels were investigated. The results showed that with the increase of EP addition (0–1 %), the gel strength initially increased and then decreased. The emulsion gel with 1 % EP had better freeze-thaw stability (36.77 %), thermal stability (78.63 °C), and water holding capacity (96.57 %). Moreover, the micromorphology results indicated that the EP-ovalbumin (OVA)-konjac glucomannan (KGM) complex showed a connected filamentous network structure, and the emulsion gel with 1 % EP addition had the most uniform and densest network structure. Furthermore, the EP emulsion gel had the highest free sulfhydryl content and hydrophobic interaction, and LEO exhibited the best antioxidant and sustained-release properties at this time. In conclusion, the findings demonstrated the potential of eggshell powder to enhance emulsion gel stability, which could improve the high-value utilization of egg by-products.

Sequential extraction of hawthorn pectin: An attempt to reveal their original mode of being in plants and functional properties

Hawthorn is rich in pectin, which is much higher than most cultivated fruits, but conventional extraction methods do not meet the requirements of low energy consumption and green production. Pectin in hawthorn is divided into soluble and insoluble parts, and with the ripening of hawthorn, the original pectin is converted into soluble pectin and pectic acid under the action of enzymes. Therefore, based on the characteristics of hawthorn pectin, this study sequentially extracted hawthorn pectin using water-soluble pectin (WSP) and hot acid-soluble pectin (HAP) method, verifying the feasibility of extracting hawthorn pectin with pure water at room temperature, and systematically analyzing and comparing the physicochemical properties and functional characteristics of the two methods. The combination of texture analysis and gel rheology revealed that WSP formed a more uniform and dense network structure during the gelation process. Additionally, microscopic observations and emulsification index results indicated that the emulsion prepared with WSP (WSE) had a smaller particle size and better stability. This indicates that hawthorn pectin is suitable for extraction with pure water at room temperature, which can maintain its good physical properties while reducing energy consumption, providing a new approach for the large-scale extraction of pectin in the food industry.

Prolonging heat-moisture treatment time at medium moisture content optimizes the quality attributes of cooked brown rice through starch structural alteration

Brown rice (BR), one of the popular whole grains worldwide, is still limited to consumption due to its rough texture after cooking. Through inspecting structural alteration, this work discloses how heat-moisture treatment (HMT) moisture content (15 %–25 %) and time (1.0 h–3.0 h) modify the starch digestibility and cooked BR texture. The medium moisture content (20 %) allowed the highest pasting viscosity and a uniform network structure of cooked BR. Prolonging the HMT time from 1.0 h to 2.0 h at medium moisture content hindered starch swelling and improved stability. Meanwhile, the relative crystallinity, the surface compactness in nanoscale and R995/1022 decreased, while the gel network structure was improved, contributing to the softened cooked BR texture and the enhanced starch digestibility. Although the resistant starch content raised to 13.55 % after 3.0 h of HMT, the springiness, gumminess and chewiness of cooked BR degraded, and this should be considered in certain conditions.

Effect and Mechanism of Zirconium Crosslinker on Retarding Degradation of HPAM/PEI Gel System in Medium-Salinity Reservoirs

Summary The objective of this paper is to investigate the effect of the addition of zirconium crosslinker on retarding the degradation of the partially hydrolyzed polyacrylamide/polyethyleneimine (HPAM/PEI) gel system. Dehydration and degradation under salinity conditions pose serious challenges to the effectiveness of the HPAM/PEI system used for water control treatment in heterogeneous reservoirs. In this study, rheological tests, Fourier transform infrared (FTIR) spectroscopy, and 13C nuclear magnetic resonance (NMR) spectroscopy are used to elucidate the characteristics and mechanisms of dehydration and degradation of HPAM/PEI gel in medium-salinity conditions. The effects of three types of zirconium crosslinkers on the gelation performance of the HPAM/PEI system are evaluated. Furthermore, the mechanism by which an organic zirconium complex (ZrOr complex) with triethanolamine (TEA) and lactic acid (LA) as ligands improves the stability of the HPAM/PEI system under medium-salinity conditions is revealed. The results indicate that ZrOr complex notably retards the degradation of the HPAM/PEI system under medium-salinity conditions (50 g/L) for more than 60 days while improving its gel strength. TEA and LA as ligands have a positive effect on crosslinking of HPAM with the organic Zr4+ complex by modulating the availability of Zr4+ and the homogeneity of the crosslinking reaction. Specifically, our data suggest that TEA stabilized Zr4+ and retarded its release through its chelating effect, while LA improved the efficiency and effectiveness of the crosslinking reaction by increasing the solubility of Zr4+ and providing additional carboxyl groups. The synergistic effect of the two ligands significantly improved the properties of the final crosslinked product. Evidence from FTIR, 13C NMR, and microstructural tests supports the conclusion that the retardation of degradation and enhancement of gelation performance in the HPAM/PEI system by ZrOr complex are associated with its crosslinking with carboxyl groups produced by HPAM hydrolysis, leading to the formation of a more uniform and compact network structure. A field trial conducted in the Beiyao Block demonstrated the potential of the ZrOr complex to extend the treatment lifetime of the HPAM/PEI gel system in medium-salinity reservoirs.

Mechanism of the G/M ratio and zein in enhancing the mechanical and hydrophobic properties of sodium alginate films

This study developed an edible film based on calcium-crosslinked sodium alginate (SA) using the casting method. The investigation assessed how the α-L-guluronic acid/β-D-mannuronic acid (G/M ratio) and zein addition influence the film's physicochemical properties. Fourier transform infrared spectroscopy and scanning electron microscopy findings suggest that the G/M ratio modulates the film's physicochemical characteristics by altering SA molecular cross-linking strength and the film's network structure density. At a G/M ratio of 0.85, the film exhibits a more uniform network structure, enhanced moisture resistance, hydrophobicity, and mechanical properties. Zein, evenly dispersed within the film matrix, establishes strong hydrogen bonds and electrostatic interactions with SA, enhancing the film's network structure and boosting its thermophysical, mechanical, and moisture resistance characteristics. The study demonstrates that modifying the G/M ratio and incorporating zein enhances the film's mechanical and hydrophobic properties, broadening its potential applications in food packaging.

Effects of NaCl/KCl ratios on structural and properties changes in soy‐potato protein mixed gel

SummaryTo reduce the sodium salt content in protein gel‐based foods, this study investigated the effects of different Na‐K ratios on the gelation properties and structural changes of soy protein isolate (SPI) and potato protein isolate (PPI) composite gels. The results showed that the composite gel properties were further enhanced with increasing Na‐K ratio in the SPI/PPI gel system. Specifically, when the Na‐K ratio was 1:1, the SPI/PPI composite gel exhibited the highest gel strength, gel elasticity, WHC, storage modulus (G′), and β‐sheet content, whereas the α‐helix content and β‐turn content were the lowest. Scanning electron microscopy images revealed a dense and uniform network structure of the composite gel. The addition of low concentrations of Na+ and K+ improved the network structure and water‐holding capacity of the SPI/PPI gel during the heat‐induced gelation process. However, excessively high Na‐K ratios weakened the gel properties.

Effect of non-covalently bound alkaline amino acids on the structural characterization, microstructure, and rheological properties of whey protein emulsion gel

The objective of this study was to explore the impact of L-arginine (Arg) and L-lysine (Lys) on the structural changes and rheological properties of whey protein isolate (WPI) emulsion gels through the utilization of multi-spectroscopic techniques and rheological analysis. The results indicated that the incorporation of Lys/Arg caused WPI molecules to become unfolded, thus exposing hydrophobic amino acids and altering the microenvironment of aromatic amino acids. Microstructural studies revealed that WPI emulsion gels containing 0.5% Lys or 2% Arg resulted in a more uniform and compact network structure. This phenomenon could be attributed to the capability of Lys/Arg to improve the hydrophobic interactions and hydrogen bonding between molecules during gel formation, ultimately leading to a network structure characterized by excellent rheological properties, textural properties, and water-holding capacity. These findings provide a theoretical for the development of emulsion gels with improved structural and rheological properties.

The fracture and toughening mechanism of double-network hydrogel using the network mechanics method

Double-network hydrogels have received considerable attention due to their superior mechanical properties. However, a comprehensive understanding of their fracture and toughening mechanisms is still lacking, primarily due to the complex network structures of double-network hydrogels and the highly non-linear characteristics of the fracture. In this study, we address this gap by developing a mesoscopic model for double-network hydrogels using the network mechanics method, in which the fracture of polymer chains is realized by introducing the stretch criterion to each polymer chain. Through numerical analysis, we find that the stretch criterion ratio of polymer chains in two networks λ2c/λ1c is the key factor that influences the necking and hardening phenomena of double-network hydrogels. By changing this stretch criterion ratio, the fracture mode of double-network hydrogels can transit between ductile and brittle. When the fracture stretching criteria of the polymer chains in the first and second networks are 1.8 and 6, the necking and hardening phenomena can be observed. It is also found that a more uniform network structure of the first network enhances the toughness of double-network hydrogels. This study sheds light on the fundamental fracture and toughening mechanisms of double-network hydrogels, providing new insights for their further applications.

Enhanced mechanical property and flame resistance of phosphorylated cellulose nanofiber based‐aerogel combined with boric acid

AbstractAs for cellulose‐based aerogels, a feature of inadequate mechanics and easy‐flammability seriously restricts their practical applications. To address this issue, herein a lightweight, mechanical elastic and flame‐retardant phosphorylated lignin‐based cellulose nanofiber (PLCNF‐B) aerogel with the aid of boric acid was successfully obtained by freeze‐drying method. Due to the uniform and tough network structure benefitting by strong hydrogen bond between phosphorylated fibers and boric acid, the resultant aerogel showed excellent mechanical performance, that is, high compressive strength of 8.9 kPa (strain: 50%) and outstanding cyclic reliability (remain 90% after 10 cycles). Meanwhile, PLCNF‐B aerogel possesses highly improved flame‐retardant property, that is, a high LOI value (up to 46%), significantly reduced peak heat release rate (11.2 W/g) and total heat release rate (0.47 kJ/g). Based on structural observation and analysis, the flame‐retardant behavior should be attributed to the formation of PxOy/amorphous boron oxide protective layer, which is derived from the phosphorus containing group of PLCNF and boric acid. The splendid overall performance of aerogel material offers a potential material tactic for design and development of advanced bio‐based aerogels for practical applications.

Physicochemical properties and in vitro digestive behavior of astaxanthin loaded Pickering emulsion gel regulated by konjac glucomannan and κ-carrageenan

This study aimed to elaborate the combination effect of polysaccharides on physicochemical properties and in vitro digestive behavior of astaxanthin (AST)-loaded Pickering emulsion gel. AST-loaded Pickering emulsion gel was prepared by heating Pickering emulsion with konjac glucomannan (KGM) and κ-carrageenan (CRG). The microstructure revealed that adding the two polysaccharides resulted in Pickering emulsion forming a network structure. It exhibited a denser and more uniform network structure, enhancing its mechanical properties four times and increasing its water-holding capacity by 20 %. In vitro digestion experiments demonstrated that the release of free fatty acids from the Pickering emulsion gel (4.25 %) was notably lower than that from conventional Pickering emulsion (17.19 %), whereas AST bioaccessibility was remarkably low at 0.003 %. It provided a feasible strategy to regulate the bioaccessibility in Pickering emulsion, which has theoretical significance to guide the current eutrophic diet people.

Osmotic dehydration with different agents induced pectin diversity: Physicochemical and structural properties of pectin from instant controlled pressure drop dried peach chips

Pectin as an important cell wall matrix that can be affected by osmotic dehydration (OD) pretreatment, determines the texture characteristics of dried fruit and vegetable products. This study investigated the effect of OD on the structural, thermal and rheological properties of pectin extracted from peach chips prepared by instant controlled pressure drop (DIC) drying. In detail, erythritol, glucose, and trehalose were selected as the osmotic agents (300 g/L). Pectin extracted from Ery-OD samples with a loose structure presented the highest molecular weight (432.9 kDa). The lowest content of arabinose (155.16 mg/g) and galactose (32.80 mg/g) were obtained in Glc-OD samples. With the infiltration of trehalose, the thermal stability of pectin was improved, which contributed to the uniform and complete network structure of pectin. 1H and 13C spectra analysis showed the significant alteration in pectin molecular structure induced by OD pretreatments, which affected the shear thinning behavior of pectin solution. Overall, the type of osmotic agents played a crucial role in the structural, thermal and rheological properties of pectin, which could reflect on the macro-texture characteristics of peach chips. This study would provide a theoretical basis for revealing the effect mechanism of OD on the texture of DIC fruit and vegetable chips at molecular level.

Effect of curdlan on the gel properties and interactions of whey protein isolate gels

This study investigated the influence of curdlan on the gel properties of whey protein isolate (WPI). Results demonstrated that curdlan significantly improved the water-holding capacity, gel strength and rheological properties of the WPI gels. Moreover, it promoted the unfolding of the molecular structures of WPI, which was manifested by the transition from α-helix to β-sheet, an increase in free sulfhydryl content and a decrease in surface hydrophobicity. Furthermore, 4 % curdlan promoted the formation of WPI with uniform and compact elastic gel network structures, primarily attributed to disulphide bonds, hydrogen bonds and hydrophobic interactions. However, when the addition of curdlan exceeds 4 %, excessive entanglement of curdlan chains and steric hindrance effects hinder the unfolding and folding of protein structures, weaken their interaction, result in a loose network structure and affect the gel properties. In conclusion, this study demonstrates that curdlan can effectively improve the gelling properties of WPI, suggesting its potential application in low-calorie gel-based dairy products.

A highly durable and biocompatible bionic collagen implant with exceptional anti-calcification and collagen regeneration capabilities for improved skin rejuvenation

Skin aging, a complex and inevitable biological process, considerably impacts an individual’s physical appearance and overall well-being. While collagen-based implants hold potential for skin rejuvenation, their clinical application is limited by the poor durability of non-crosslinked implants and the negative impacts of crosslinking agents, such as cytotoxicity and calcification. Herein, we report a highly durable and biocompatible bionic collagen implant for superior skin rejuvenation with advanced anti-calcification characteristics and enhanced collagen regeneration. Utilizing biomimetic self-assembly and covalent crosslinking approach, we successfully created long-lasting and biomimetic collagen implants with densely-packed collagen fibers. Crosslinking of collagen fibers with a low concentration of N-hydroxysuccinimide activated suberic acid (NHS-SA) was highly efficient, resulting in complete crosslinking and thicker collagen fiber formation with a uniform network structure. Compared with glutaraldehyde-crosslinked collagen fibers, NHS-SA-crosslinked assembled collagen fibers (NACF) demonstrated considerably improved thermal stability and durability. Furthermore, the NACF implant exhibited superior biocompatibility, establishing NHS-SA crosslinked collagen fibers as a safer and more bioactive choice for implant applications. In mouse subcutaneous implant models, the NACF implant outperformed other collagen implants, demonstrating exceptional biocompatibility, effective collagen regeneration, and excellent anti-calcification potential. The NACF implant shows immense promise in collagen regeneration, offering considerable potential to advance skin rejuvenation therapies.

Development of corn starch-sodium alginate emulsion gels as animal fat substitute: Effect of oil concentration

Emulsion gels were prepared utilizing corn starch (CS), sodium alginate (SA), and corn oil through calcium ion induction for animal-fat analogs. The influence of oil concentration on the rheological properties, microstructure and lipid oxidation of the emulsion gel was analyzed. Results revealed that the emulsion gel containing 30% (v/v) oil exhibited no surplus oil leakage and demonstrated the highest gel strength. The results of the small amplitude oscillatory shear (SAOS) and large amplitude oscillatory shear (LAOS) test proved that the emulsion gel exhibited the greatest elasticity and deformation resistance when the oil content was 30% (v/v), imparting suitable mouth feel and transport stability as an animal fat substitute. Microstructure analysis indicated that SA crosslinked with Ca2+ to generate a network structure accompanied by the reinforcing effect of starch granules, enabling the dense network to capture an optimal quantity of oil to form a uniform gel network structure. Furthermore, the emulsion gel exhibited markedly lower lipid oxidation compared to bulk oil after 14 days of storage. As a new fat analog system, the CS-SA emulsion gel holds promising potential for applications in the food industry.

Preparation and Effect of CO2 Response Gel for Plugging Low-Permeability Reservoirs.

In order to solve the problem of gas channeling during CO2 flooding in low-permeability reservoirs, a novel CO2 responsive gel channeling system was prepared by using carrageenan, branched polyethylene imide and ethylenediamine under laboratory conditions. Based on the Box-Behnken response surface design method, the optimal synthesis concentration of the system was 0.5 wt% carrageenan, 2.5 wt% branchized polyethylenimide and 6.5 wt% ethylenediamine. The micromorphology of the system before and after response was characterized by scanning electron microscopy. The rheology and dehydration rate were tested under different conditions. The channeling performance and enhanced oil recovery effect of the gel system were simulated by a core displacement experiment. The experimental results show that the internal structure of the system changes from a disordered, smooth and loosely separated lamellae structure to a more uniform, complete and orderly three-dimensional network structure after exposure to CO2. The viscosity of the system was similar to aqueous solution before contact with CO2 and showed viscoelastic solid properties after contact with CO2. The experiment employing dehydration rates at different temperatures showed that the internal structure of the gel would change at a high temperature, but the gel system had a certain self-healing ability. The results of the displacement experiment show that the plugging rate of the gel system is stable at 85.32% after CO2 contact, and the recovery rate is increased by 17.06%, which provides an important guide for the development of low-permeability reservoirs.

Intelligent solar-driven “switch” photothermal hydrogel for clean water harvesting

Water shortage is becoming a huge challenge to mankind. Inspired by pufferfish, we developed an intelligent solar-driven “switch” hydrogel system PEG-PNIPAAm/Fe3O4 hydrogel (PPFH). This hydrogel system is characterized by a uniform porous network structure formed by the integration of hydrophilic PEG, temperature-responsive PNIPAAm polymer and Fe3O4 photothermal nanoparticles. The three-dimensional porous structure provides a higher surface area, offering more adsorption sites for water molecules. The interaction between PPFH and water primarily relies on the hydrogen bonding between the amide groups in PNIPAAm and water molecules, which enhances the hydration of the hydrogel network for rapidly water harvesting. However, when exposed to sunlight, the presence of Fe3O4 nanoparticles causes the ambient temperature to rise rapidly above the LCST, the hydrogen bonding between molecules gradually weakens, while the hydrophobic interactions among the hydrophobic groups in PNIPAAm become stronger, causing the polymer chains to contract and water releasing. The fog capture performance of PPFH can reach up to 3.2 g g−1, and under the irradiation of a sunlight (1 kW m−2), the captured water can be released within 8 min, and the water release efficiency reaches 94 %. This design concept provides the possibility for promoting the widespread implementation of hydrogels-based solar evaporators in practical purification systems in the future, alleviating water shortages issues.

Synergistic effects and interactions among components in the surimi/κ-carrageenan/soybean oil system

When κ-carrageenan (KC), soybean oil, and surimi are mixed in appropriate proportions, they demonstrate significant synergistic effects. This study established a ternary system composed of surimi, KC, and soybean oil, exploring the synergistic effects and interactions among surimi, KC, and oil from multiple dimensions, including gel properties, rheological behavior, Raman spectroscopy, and microstructure. Gel strength analysis revealed that when the KC concentration was 4.0% (w/w), the surimi gel exhibited the highest gel strength. Moreover, the addition of an extra 5.0% oil further enhanced the gel strength. Rheological analysis indicated that the highest storage modulus (G′) exhibited by the ternary system containing 5.0% oil is the result of synergistic effects among surimi, KC, and oil. Raman spectroscopy further uncovered the hydrogen bonding and electrostatic interactions between surimi proteins and KC, the hydrophobic interactions between surimi proteins and oil, and the hydrogen bonding between KC and oil. The results from scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) indicated that, compared to the pure surimi gel, the Surimi/KC/Oil ternary gel containing 5.0% oil exhibits a more compact and uniform network structure, attributable to the filling effect of KC and oil on the gel network. These results indicate that the synergistic effects and physicochemical interactions among surimi, KC, and oil in appropriate proportions can promote the formation of a stable and compact gel network structure.