Final Gel Strength Research Articles

Exploring the potential of plant-based emulsion gels enriched with β-glucan and potato protein as egg yolk alternatives

This study investigated the microstructure, physicochemical properties, and digestibility of plant-based egg yolk (PBEY) as a potential replacement for real egg yolk (REY). The PBEY consisted of oil-in-water emulsions containing β-carotene and vitamin D in the oil phase and β-glucan and potato proteins in the aqueous phase. The potato proteins were used as natural emulsifiers and gelling agents, the β-carotene was used as a natural yellow pigment, and the β-glucan, β-carotene, and vitamin D were used to improve the nutritional profile. In aqueous solutions, β-glucan was susceptible to aggregation and precipitation. However, it remained stable in PBEY during storage, which was attributed to non-covalent interactions between the potato proteins and β-glucan. β-glucan increased the apparent shear viscosity and shear thinning behavior of the PBEY, which was attributed to its polymeric nature. The thermal gelling properties of the PBEY were also affected by β-glucan addition, with a decrease in gelation temperature and final gel strength, indicating changes in gel structure. The addition of β-glucan also increased the hardness and resilience of the egg analogs, with 2.5 wt% yielding properties like REY in terms of springiness and chewiness. The color matching theory was used to match the color of the PBEY to REY. Optimizing the concentration of β-carotene in the PBEY allowed us to successfully match the yellow color of REY. The presence of β-glucan in the PBEY increased protein hydrolysis during simulated gastric and small intestinal digestion, but it decreased lipid hydrolysis and vitamin D bioaccessibility in the small intestine. This reduced bioaccessibility was attributed to the ability of the polysaccharide to inhibit the digestion of the protein-coated oil droplets. This study provides an improved understanding of how β-glucan affects the properties of nutrient-fortified PBEY. The PBEY developed in this study may be suitable for consumers seeking healthy and sustainable plant-based alternatives to REY. However, further research is required to test the sensory properties.

Insights into the textural properties and starch digestibility on rice noodles as affected by the addition of maize starch and rice starch

The effects of maize starch (MS) and rice starch (RS) addition on rice noodle quality were investigated, aiming to develop high-quality noodles with both desirable textural properties and low starch digestibility. The results showed that the MS had more short branch chains and higher branch density when compared to RS, and the final viscosity and gel strength of rice paste decreased with its addition. The textural properties between rice noodles with less than 20% MS and without MS did not differ significantly, while the network structure of rice noodles with more MS was significantly weakened due to the steric hindrance of short branch chains. The addition of RS increased the texture quality of rice noodles. Moreover, their addition reduced the estimated glycemic index of rice noodles, because more starch promoted the arrangement of starch chains and formed ordered double helix. The MS with more short chains was conducive to the formation of double helix to reduce digestion rate, and the RS with more long chains formed stabler gel and crystal structures to reduce digestible starch content. Therefore, MS and RS addition had potential to produce rice noodles with high comprehensive quality, and MS content should be controlled below 20%.

Chitosan/Polyacrylamide Green Gels for Water Control in High-Temperature Reservoirs

The rheology of a gel system composed of polyacrylamide (PAM) and chitosan is studied under typical reservoir conditions. The impacts of the degree of chitosan deacetylation, temperature, and salinity on the gelation behavior are assessed. The said system was prepared under ambient conditions and matured for 24 h at altered temperatures ranging from 50 up to 125 °C. An optimum formulation has been identified considering the rheological response and the initial viscosity constraints. The increase in the degree of syneresis with the degree of deacetylation indicates the long-term thermal stability of the gels. Ammonium chloride was an effective retarder for the PAM/chitosan gelant, which delayed the gelation time from 60 to 210 min when 2 wt % is used; however, it compromised the final gel strength. The chitosan/PAM system showed a good rheological behavior and potential as a green plugging agent in high-temperature oil and gas wells. Chitosan could be an alternative for commercial crosslinkers, such as polyethyleneimine.

Meat analog production through artificial muscle fiber insertion using coaxial nozzle-assisted three-dimensional food printing

In this study, we propose a method for the texture of meat analogs through artificial muscle fiber insertion based on cross-linkable hydrocolloids using a coaxial nozzle-assisted three-dimensional (3D) food printer. Hydrocolloid-based muscle fiber simulation material was prepared in 2.5–5% solutions with different formulations of kappa and iota carrageenan (CG), sodium alginate (SA), and glucomannan (GM). During the coaxial nozzle-assisted 3D food printing process, all samples were cured using K+ and Ca2+. The fiber solution before post-processing formed a gel by SA ionic bonding; subsequently, the gel strength increased due to CG structural changes and the synergy between CG and GM. Therefore, with respect to the rheological properties, all samples, except for CG(1.5)GM(0), formed a hard gel. However, concerning the texture properties, only CG(1.5)GM(1.5) and CG(2.5)GM(1.5) displayed an elastic strength comparable to that of actual meat due to GM elastic gel formation, and CG(2.5)GM(1.5) displayed the highest hardness. Post-processing the product quality was investigated by determining shrinkage and cooking loss. We found that transversal shrinkage was higher than longitudinal shrinkage, and cooking loss was reduced in the samples. These results were visibly related to the final gel strength. In this study, we successfully tested the embodiment of texture, which is a challenge for alternative meat, using a coaxial nozzle-assisted 3D food printer. This system uses hydrocolloids as a carrier to insert functional materials, and we confirmed the possibility of applying it to other foods that require texture embodiment.

The effects of casein and whey proteins on the rheological properties of calcium-induced skim milk gels

This study aimed to determine the interactive effects of casein, whey proteins and calcium ions on the rheological properties of calcium-induced skim milk gels. Skim milk blends with different casein to whey protein ratios (95:5, 93:7, 90:10, 85:15 and 80:20) were either not preheated or preheated at 90 °C for 10 min, and calcium chloride was added at 0–40 mmol L−1. Results suggested that the final gel strength (G′) was dependent on the concentration of added calcium chloride, ratio of casein to whey proteins, and whether the whey proteins were denatured by preheat treatment. Denatured whey proteins in preheated skim milk blends appeared to lead to two competing effects on the gel strength: reduced gel strength due to competition with casein micelles for calcium ion binding; and enhanced gel strength by participating in the gel structure through aggregation via calcium-bridging, hydrophobic interactions, and disulphide bonding.

Effect of antinutrients on heat-set gelation of soy, pea, and rice protein isolates.

Plant-derived protein can present antinutrients (ANs) in its composition. The ANs can interact with the protein, affecting its solubility and functional properties, such as gelation. This work evaluated the effect of three ANs, namely phytic acid (PA), tannic acid (TA), and Quillaja bark saponin (QBS), on the gelation and solubility of soy (SPI), pea (PPI), and rice protein isolate (RPI). The ANs altered the protein isolates gelation and solubility. PA decreased the solubility and gelation of the three protein isolates at pH 3.0. The TA was the AN that most decreased the solubility and gelation characteristics of SPI and PPI at both pHs analyzed. QBS increased the gelation of SPI at pH 3.0 but decreased the final gel strength of RPI at the same pH. These results show that the knowledge of the presence of ANs in the protein isolates is of fundamental relevance for the processing of vegetable proteins.

Acetylation of intact white rice grains to alter the physicochemical properties

The effect of acetylation of milled rice grains of selected varieties (TDK 8, YRW 4, Reiziq, Amber 33, and SHZ 2) with varying apparent amylose contents (3.8–26.6%) on their physicochemical properties was investigated. Milled rice samples were treated with different acetic anhydride concentrations (0.004–0.04 g per 100 g of milled rice samples in 225 mL of water). Results showed that glutinous (TDK 8), very low amylose (YRW 4) and low amylose containing varieties (Reiziq) were prone to acetylation even with 0.004 g of acetic anhydride. X-ray diffraction patterns showed an increase in the crystallinity in acetylated samples and formation of V-type crystals, suggesting the possible interaction of acetic anhydride with starch. Acetylation of rice grains resulted in reduced peak and final viscosities and gel strength, particularly in glutinous (TDK 8) and very low amylose (YRW 4) rice. Differential calorimetric study showed that acetic anhydride treatment resulted in reduced thermal transition temperatures and enthalpy of all varieties. Although increase in the retrogradation thermal temperatures was observed, the enthalpy of retrogradation was reduced with increasing acetylation, suggesting that the extent of starch retrogradation was lower in all varieties with more prominent reduction in the glutinous type. Furthermore, the texture of cooked acetic anhydride treated rice grains was less hard and showed more adhesiveness. This study demonstrated that the acetylation of rice grains (instead of flour) was successfully achieved, showing the potential of applying acetylation to alter the textural, pasting, thermal and retrogradation properties of rice.

Influence of O/W emulsion on gelatinization and retrogradation properties of rice starch

An investigation was conducted into the effects of micro- and nano-emulsion on gelatinization and retrogradation of rice starch (RS). According to the results, the addition of emulsion contributed to the decline in the maximum viscosities, gelatinization enthalpy and a restriction on granular swelling during the gelatinization process of RS, and reduce the final gel strength of RS. During storage at 4 °C of the starch gel, the addition of emulsion was discovered to reduce the gel firmness and water mobility of RS gels during cold storage. The crystallinity of RS was found to be reduced from 11.59% to 6.81% after storage at 4 °C for 14 days. The microstructure of RS gel with emulsion was observed to be denser and more uniform compared with that of RS without emulsion after cold storage. As indicated by the result of starch retrogradation, emulsion was capable to prevent the interactions between starch molecules, retain the compact structure of starch gel, and decline the mobility of starch intra-granular water. These findings suggested that the addition of emulsion inhibited the short- and long-term retrogradation of RS, and promoted the application of emulsion in the starchy foods.

Effect of Ohmic Heating on the Formation and Texture of Acid Milk Gels

This study aimed to describe the effects of ohmic heat treatment (OHT) of milk on the formation and properties of acid milk gels. The influence of voltage gradient (25, 40, 55 V/cm), holding time (2, 16, 30 min), and final temperature (45, 65, 75, 85 °C) on rheological properties and particle size distribution was measured during the gelation process. Texture properties and syneresis of the samples were evaluated at the end of the gelation process. Scanning electron microscopy (SEM) micrographs of the acid milk gels were also taken at pH 4.6(i.e., pI or Isoelectric point of casein). Results indicated that oscillatory time sweep tests were more accurate than particle size measurements in detecting gelation onset. Complex modulus values of the final gel showed that OHT of the milk at 25 V/cm and holding at 85 °C for 16 min gave rise to a 21% higher structural strength compared to when using the conventional heat treatment (CHT) where temperature was 85 °C and holding time and come up time were 30 and 20 min respectively. In other words, by using the OHT milk, the same gel strength as that of CHT 85 °C sample was obtained by spending 185 min instead of 328 min incubation time (i.e., 40% less time). Higher voltage gradient lowered the final gel strength when temperature and holding time kept constant at 85 °C and 16 min respectively. Results indicated that the gel firmness enhanced and the amount of syneresis decreased when CHT was replaced by OHT in the manufacturing process. SEM revealed that the protein matrices of ohmic heating samples appeared to be more compact and denser with smaller pore size than observed in the conventional gel. Results indicated that OHT of milk successfully improves the quality of acid milk gels and obviate the need for increasing dry matter concentration or using additives.

Gelation Kinetics of Hydrogels Based on Acrylamide⁻AMPS⁻NVP Terpolymer, Bentonite, and Polyethylenimine for Conformance Control of Oil Reservoirs.

Relatively smaller volumes of gelling systems had been used to address conformance problems located near the wellbore in oil reservoirs with harsh temperature and salinity conditions. These gelling systems were formulated with high concentrations of low-molecular-weight acrylamide-based polymers crosslinked with polyethylenimine (PEI). However, for in-depth conformance control, in which large gelant volumes and long gelation times were required, lower-base polymer loadings were necessary to ensure the economic feasibility of the treatment. In this study, a gelling system with high-molecular weight 2-acrylamido-2-methylpropane sulfonic acid (AMPS), N-vinyl-2-pyrrolidone (NVP), acrylamide terpolymer, and PEI, with the addition of bentonite as a filler, was formulated. The influence of the gelant formulation and reservoir conditions on the gelation kinetics and final gel strength of the system was investigated through bottle tests and rheological tests. The addition of clay in the formulation increased the gelation time, thermal stability, and syneresis resistance, and slightly improved the final gel strength. Furthermore, samples prepared with polymer and PEI concentrations below 1 wt %, natural bentonite, and PEI with molecular weight of 70,000 kg/kmol and pH of 11: (i) presented good injectivity and propagation parameters (pseudoplastic behavior and viscosity ~25 mPa·s); (ii) showed suitable gelation times for near wellbore (~5 h) or far wellbore (~21 h) treatments; and (iii) formed strong composite hydrogels (equilibrium complex modulus ~10–20 Pa and Sydansk code G to H) with low syneresis and good long-term stability (~3 to 6 months) under harsh conditions. Therefore, the use of high-molecular-weight base polymer and low-cost clay as active filler seems promising to improve the cost-effectiveness of gelling systems for in-depth conformance treatments under harsh conditions of temperature and salinity/hardness.

Effect of starch modification in the whole white rice grains on physicochemical properties of two contrasting rice varieties

The effect of acetylation of milled rice of selected rice varieties viz. TDK8 and DG on their physicochemical properties was investigated at different acetic anhydride concentrations (1–7 g per 100 g of milled rice samples in 225 mL of water). Results showed that the intact starch of milled grains of both selected verities could be acetylated (Acetyl % for TDK8 = 2.18 and for DG = 0.89) even with 1 g of acetic anhydride. X-ray diffraction patterns showed that acetylation resulted in reduced crystallinity. Acetylation resulted in reduced peak and final viscosities and gel strength, particularly in glutinous (TDK 8) and non-glutinous (DG) rice. Thermal study showed acetylation resulted in reduced thermal transition temperatures and enthalpy of both varieties. Although the increase in retrogradation thermal temperatures was observed, the amount of retrograded starch was decreased in both varieties. Furthermore, the texture of cooked acetylated grains was less hard and more adhesive. In vitro digestion showed significant decrease in GI possibly due to structural changes in the native starch during acetylation. These findings suggest a good potential of applying acetic anhydride pre-treatments in rice processing, especially glutinous varieties to control the hardness and maintain the stickiness properties of rice.

Fluid loss control mechanism of using polymer gel pill based on multi-crosslinking during overbalanced well workover and completion

Recently, polymer gel used as fluid loss pill for well workover and completion is reported more, while it mainly focuses on using single crosslinking mechanism. To the best of our knowledge, polymer gel based on multi-crosslinking is commonly used in the aspect of water shutoff. The theory of multi-crosslinking for preparing polymer gel has rarely been used in overbalanced well workover and completion. In this paper, we conduct experimental study to reveal the physical process and fluid loss control mechanism of the polymer gel pill based on multi-crosslinking during overbalanced well workover and completion. We propose the design philosophy of the multi-crosslinking based on two or three crosslinking reactions under different conditions. In this paper, the first gelation reaction of the target polymer gel is between a kind of high-temperature resistance acrylamide based polymer (abbreviated as “SPAM”) and fresh chromium acetate as metallic-ion crosslinker to quickly form a pre-crosslinking gel with strength of around Code C at surface temperature of 30°C. It aims at guaranteeing pumping performance and restricting free water for lowering the risk of fluid loss in inner tube wall and or the separation of polymer and crosslinker during pumping process. Subsequently, with the increasing of wellbore temperature during the pumping process, the pre-crosslinking gel will gradually become mature (when gel reaches at the final gel strength) to form high strength gel by the use of either polyethyleneimine (PEI) or hexamethylenetetramine (HMTA) or both as organic crosslinker(s) through covalent bonding. The mature polymer gel can realize the complete crosslinking structure to guarantee gel thermal stability. The mature polymer gel pill based on multi-crosslinking formulated with a combination of SPAM, fresh Chromium acetate, PEI and HMTA indicates an obvious viscoelasticity characteristic at high temperature of 150°C, while exhibiting a notable elastic performance for the formula without crosslinker HMTA. The fluid loss evaluation experiment result shows that the mature polymer gel based on multi-crosslinking can really act as fluid loss pill to withstand high positive pressure during overbalanced well workover and completion. Whilst there is some degree of permeability damage for the treated core, but not too high. Besides, the scanning electron microscope (SEM) is further employed to reveal the fluid loss control mechanism of the mature polymer gel at the micro level. This study provides an avenue to implement polymer gel pill based on multi-crosslinking for fluid loss control during overbalanced well workover and completion.

Evidence of the Gelation Acceleration Mechanism of HPAM Gel With Ammonium Salt at Ultralow Temperature by SEM Study

Summary Previously reported phenol-formaldehyde-based gel formulas with ammonium salt can provide a gelation time between 2 hours and 2 days at 25 °C, which has great potential to serve as water-shutoff or conformance-control agents in ultralow- to low-temperature reservoirs. The gelation performance can be adjusted by changing the concentration of hydrolyzed polyacrylamide (HPAM), crosslinker, and ammonium salt. Over the last decades, the working behavior of a gel system in a reservoir has been evaluated simply through the gelation-performance bottle test and the effectiveness of gel treatment at the macro level. However, the nature of a gel microstructure greatly dominates its working performance in subterranean reservoir conditions. The objective of this work is to investigate the relationship between gelation performance and microstructures of target gel by scanning-electron-microscope (SEM) analysis at different test conditions, including the effects of components concentration, aqueous-phase salinity, and porous-medium shearing, and to reveal evidence of the gelation-acceleration mechanism. Results show that ammonium salts act as bridging branch chains between polymer and crosslinker to accelerate the gelation progress. We reveal the gelation-process indicator through the discovery of several “coverings” that appeared among the polymer branch chains. The gelation-acceleration mechanism should be the embedding and growth of crystalline ammonium salts in the polymer skeleton to promote the extension of these coverings. The polymer skeleton covered by crystalline ammonium salts can increase the gel strength and salinity tolerance as a result of the unique structure of “crab's big claws.” The gelation performance is not seriously affected by the shearing effect in porous media, while the final gel strength still can reach Code I and exhibit a favorable long-term stability. Some application recommendations of the target gel are also discussed in this paper.

Biochemical and rheological characterization of a protease from fruits of Withania coagulans with a milk-clotting activity

A protease from Withania coagulans fruits was evaluated for milk-clotting properties. The optimum temperature and pH for enzyme activity were 70°C and 4, respectively. The protease also exhibited an excellent thermal stability at 60°C for 30 min. Fractional precipitation using ammonium sulfate showed that the 40–50% fraction (F5) possessed the highest milk-clotting activity. The F5 fraction showed a Mw band of 66 kDa by SDS-PAGE. Gel formation was monitored using low amplitude oscillatory rheology at different temperatures. An Arrhenius plot was used to describe the temperature dependence of the gelation rate parameter. Time sweep testing showed that an increase in temperature was accompanied by a decrease in the gelation onset time, a higher gel formation rate, and higher values for final gel strength. W.coagulans fruits have potential for use as a rennet substitute.

The gelation of oil using ethyl cellulose.

The characterization of the thermo-gelation mechanism and properties of ethyl cellulose/canola oil oleogels was performed using rheology and thermal analysis. Thermal analysis detected no evidence for thermal transitions contributed to secondary conformational changes, suggesting a gelation mechanism that does not involve secondary ordered structure formation. Rheological analysis demonstrated a relationship between the polymer molecular weight and the final gel strength, the cross-over behavior as well as the gel point temperature. Increasing polymer molecular weight led to an increase in final gel strength, the modulus at cross-over, and the gel point temperature. Cooling/heating rates affect gel modulus only for the low molecular weight samples. A decrease in gel strength with increasing cooling rate was detected. The cross-over temperature was not affected by the cooling/heating rates. Cooling rate also affected the gelation setting time where slow cooling rates produced a stable gel faster.

Effect of calcium source and exposure-time on basic caviar spherification using sodium alginate

Gelation speed is directly proportional to the concentration of calcium. Although the kinetics of gelation are altered by the source of calcium, the final alginate gel strength nor the resistance to calcium diffusion are altered. Calcium chloride reaches a gel strength plateau fastest (~100s), followed by calcium lactate (~500s) and calcium gluconoate (~2000s). Calcium chloride is the best option when the bitter taste can be masked and a fast throughput is required, while calcium gluconoate may have an advantage when the membrane thickness/hardness needs to be manipulated.

PHYSICO‐CHEMICAL AND FUNCTIONAL PROPERTIES OF PROTEINS OF TILAPIA (OREOCHROMIS MOSSAMBICUS)

ABSTRACT The properties of total proteins from fresh tilapia (Oreochromis mossambicus) have been assessed. The meat had high moisture (81.34%) and low lipid (<1%) content. The nitrogen solubility index, with water as solvent, showed minimum solubility of 25.52% of total nitrogen at pH 6.0. The solubility profile of total proteins as a function of molar concentration of sodium chloride indicated maximum solubility at 0.8 M and thereafter it decreased. The total proteins comprised three different fractions as revealed by gel filtration profile. The high molecular weight component was more predominant. The sodium dodecyl sulphate polyacrylamide gel electrophoresis pattern revealed multiple bands in the molecular weight range of 205–18 kDa. Higher value of adenosine triphosphatase (ATPase) activity (4.1 µg Pi/mg of protein/min) obtained in the present study may be due to combination of sarcoplasmic and myofibrillar ATPase activity. High modori‐inducing proteases (MIPase) activity at 55C was observed in the muscle extract that might interfere in the gelling ability. The gel‐forming ability of tilapia meat was found to be moderate as indicated by large strain and small strain test.PRACTICAL APPLICATIONSTilapia is one of the growing aquacultured species all over the world. In India, the mossambique Tilapia (Oreochromis mossambicus) was introduced in inland water bodies like reservoirs to boost the production. Because of its prolific breeding habit and occupation of similar trophic niches, this species has overpopulated many bodies of water. Hence, there is growing need to utilize this species for surimi production and, consequently, generate more revenues for the inland fisheries sector. Knowledge of the physicochemical and functional properties of this species would help in understanding its suitability in surimi production. The rheological properties like dynamic viscoelastic behavior, flow profile, Ca‐ATPase activity, and MIPase activity would shed light on the final gel strength of the surimi prepared from this species, and also indicate the guidelines for ameliorating the quality of the gel by addition of different concentrations of cryoprotectants or change of washing cycles.

NMR relaxometry and rheology of ionic and acid alginate gels

The relationship between NMR relaxometry and rheology of acid alginate gels has been investigated in vitro and compared to that of ionic alginate gels. The onset and early stages of the gelation process were characterized by the time dependent changes in the storage modulus G′ and transverse relaxation rate R2 of the water, demonstrating how this NMR parameter can be used as a non-invasive/non-destructive indicator of the formation of these gels. Compression tests on the final gels showed that the acid gels were much weaker. No direct correlation was observed between the final strength of these types of gels and the measured NMR R2 values. The results suggest that in MRI studies in vivo the R2 relaxation rate could provide valuable information on the rate of gelation (but not on the actual final gel strength) of alginate-containing foods in the human gastric lumen.

Rheological and gelation properties of rice starch modified with 4-α-glucanotransferase

Rheological measurements were performed to characterize rice starch modified with 4-α-glucanotransferase (4αGTase) isolated from Thermus scotoductus, in terms of effects of the enzyme and starch concentration on flow behavior, gel strength, and melting and gelling kinetics of the modified rice starch. Consistency index decreased and flow behavior index increased with the level of enzyme treatment, and at high level of enzyme treatment, it demonstrated Bingham plastic behavior. As the level of enzyme decreased and the starch concentration increased, gelation time decreased and the final gel strength increased significantly. Regardless of treatment variables, all the modified starch gels melted at similar temperature.

The effect of binary cosolvent systems (glycerol–sucrose mixtures) on the heat‐induced gelation mechanism of bovine serum albumin

SummaryThe influence of cosolvent composition on the thermal denaturation and gelation of bovine serum albumin (BSA) has been studied. Cosolvent composition was varied by changing the ratio of glycerol to sucrose in 40 wt% cosolvent solutions containing BSA. Differential scanning calorimetry measurements on 0.5 wt% BSA solutions showed that the thermal denaturation temperature of the protein increased with increasing sucrose content. Temperature scanning dynamic shear rheology and turbidity measurements on 4 wt% BSA solutions showed that the gelation temperature and final gel strength increased with increasing sucrose concentration. These observations were attributed to the fact that sucrose was more effective than glycerol at increasing the thermal stability and attraction between globular BSA molecules through a steric exclusion effect. The molecular origin of these effects is the tendency for the system to minimize the contact area of the protein molecules with the surrounding cosolvent solution.