Properties Of Mixed Gels Research Articles

Construction of mixed gels of yolk granules and salted ovalbumin driven by pH: phase behavior and calcium bioaccessibility

Mixed gels of egg yolk granules (EYGs) and salted ovalbumin (SO) with different pH values were constructed to design gels of great quality and nutritional properties. However, the formation and dietary properties of mixed gels may be affected by the phase behavior of the mixed protein solution. In this study, the pH was adjusted from 3.0 to 8.0 to tune phase behavior of mixed protein solution before heating. The results demonstrated the presence of a collapsed gel and a dense phase network at pH 3.0 caused by phase separation. As the pH increased and phase separation disappeared, the EYGs-SO gel network showed a filling network structure and then changed to a loose interpenetrating network gel structure with a decreased fractal dimension (from 2.94% to 2.89%). The interpenetrating network improved gel hardness and water-holding capacity. During gelation, the phase separation reduced the gelation transition temperature. The main forces that support EYGs-SO gel were hydrogen and disulfide bonds. Moreover, EYGs-SO showed greater calcium bioaccessibility (7.85%–8.08%) at pH 3.0, 4.0, and 5.0. In summary, the phase behavior in mixed solution modulates the gelation of mixed gels. The construction of mixed gels also provides ideas and strategies for the value-added utilization of salted egg whites.

Characterizing acidified and renneted gels with different soy milk and skim milk proportions

To understand the properties of differently acidified and renneted gels with different soy milk and skim milk proportions, mixed milks were prepared and treated using sequenced renneting then acidification at 4 °C, and the formation, spontaneous whey separation, and microstructure of the gels were monitored. The results showed that both acidification and renneting promoted gel formation in mixed milk and increased gel strength. In gels, the pH range was narrow (pH ≤ 5.2) at low soy milk proportion (25%) and low renneting degrees (0%, 25% and 50%), and the pH range was extended such that gels were formed with increasing soy milk proportion and renneting degree. When compared with pH, soy milk proportion and renneting degree influenced whey separation percentages more strongly. Soy milk significantly reduced whey separation percentages in gels, and gel strength was highest at 50% soy milk. Protein aggregates sizes increased with increasing soy milk proportion at the 75% renneting degree, and the pore sizes of skim milk-dominated gels was strongly influenced by acidification. These results help us understand mixed gel properties and provide valuable information for the manufacture of mixed fermented dairy products.

Microstructure determined the gel properties of gelatin/dextran more than the macrophase separation

Hydrogels are important in foods. Although the hydrogel microstructure has been commonly reported, the effect of the microstructure before and after gelation on gel properties was rarely investigated. This work aims to explore the effects of micro- and macro-phase separation of type-A gelatin-dextran (GE A /DE) aqueous solutions on the rheological, texture, and hydration properties of GE A /DE hydrogels. Three types of phase separation microstructures at both pH 5.0 and 7.0, e.g., DE-in-GE A emulsion, bicontinuous microstructure, and GE A -in-DE emulsion, were designed by adding different DE concentrations. GE A /DE mixtures showed macro-stability at pH 5.0, but macroscopic phase separation at pH 7.0, in which the phase separation time increased with the increasing DE concentration. During cooling-gelation, microstructures of mixtures were almost unchanged at pH 5.0, but significantly changed at pH 7.0. Interestingly, the microstructure determined the gel properties of phase-separated gels more than the macrophase separation. Microstructures of continuous phase with the gelling ability, e.g., DE-in-GE A and bicontinuous phase, hardly changed the moduli ( G′ and G″ ) and hardness of GE A /DE mixed gels, while the microstructure of GE A -in-DE without the gelling ability for continuous phase greatly reduced the moduli and hardness. This might be due to the different GE A volume fractions in GE A /DE mixed gels with different microstructures, and the mixed gel strength decreased with decreasing GE A volume fractions. Water holding capacity and swelling ratio of GE A /DE mixed gels reduced with the increasing DE concentration. This work provides some new information on how microstructure and macro-stability affect the physical properties of mixed gels. Effect of microstructure of GE A /DE before and after gelation on G′ and G″ at pH 5.0 and 7.0. • Three microstructures were designed based on gelatin/dextran phase separation. • Microstructures of macro-stable gelatin/dextran at pH 5.0 unchanged after gelation. • Microstructure determined gel properties more than the macrophase separation. • GE A volume fraction in the mixed gel might explain the effect of microstructures. • The gel strength of gelatin/dextran decreased with decreasing GE A volume fraction.

Effect of partial substitution of NaCl by KCl , CaCl 2 , and MgCl 2 on properties of mixed gelation from myofibrillar protein and Flammulina velutipes protein

The effects of substitution of sodium chloride (NaCl) by chloride salt mixtures (KCl, CaCl2, and MgCl2) with different formulas on quality characteristics of mixed protein system containing 80% myofibrillar protein (MP) and 20% Flammulina velutipes protein (FVP) were investigated in this study. The addition of chloride salts (KCl, CaCl2, and MgCl2) into a reduced-sodium (0.3 M NaCl) mixed gel system, increased the gel properties, and network structure of the MP-FVP gel, which might be attributed to the increase in protein solubility and rheological properties. The examination of the turbidity, particle size, zeta potential, UV spectroscopy, and Fourier transform infrared spectroscopy indicated that the protein molecules were obviously aggregated, that the electrostatic interaction was weakened, that the hydrophobic interaction and β-sheet content was increased. The results showed that when KCl, CaCl2, and MgCl2 were used to replace NaCl at 35, 10, and 5%, respectively, the gel properties reached the maximum. Practical applications This study evaluated the effects of different types of sodium salt substitution on the structural properties of proteins and the structural properties of mixed myofibrillar protein and Flammulina velutipes protein gels. The results revealed that the mixed protein molecules apparently aggregated under different replacement of KCl, CaCl2, and MgCl2 (i.e., 35, 10, and 5%). The hydrophobicity and β-sheet content significantly increased, while the electrostatic interaction decreased, leading to enhanced mixed gel properties. The results indicated the different replacements of sodium salts could improve the gels characteristics, which may be a guide for the future production of low-salt meat products.

Acid-induced gelation of thermal co-aggregates from egg white and hempseed protein: Impact of microbial transglutaminase on mechanical and microstructural properties of gels

The thermal co-aggregates from mixed egg white protein (EWP) and hempseed protein isolate (HPI), named mixed EWP/HPI aggregates, was produced by heating the mixture solutions (5.0% w/v) at different EWP/HPI weight ratios (0/100, 75/25, 50/50, 25/75 and 100/0) under alkaline pH. Subsequent, the acid gelation of the thermal aggregates was induced by adding glucono-δ-lactone (GDL). The thermal treatment at alkaline pH produced the aggregates assembled by both disulfide and non-disulfide covalent bonds, and they exhibited low viscosity, and high solubility EWP alone formed gels of high mechanical strength in the presence of GDL, whereas no gels were obtained from the thermal aggregates of HPI alone. The EWP/EWP aggregates of different EWP/HPI ratios formed acid-induced self-supported gels. With increasing HPI content, the elastic modulus, tan δ, creep performance, texture parameters, fracture stress/strain, and microstructural homogeneity of the mixed EWP/HPI gels tended to decrease. Treatment with transglutaminase (TGase) relatively improved the mechanical properties of mixed gels, but not enough to completely off-sets the weakening effects. This research has offered insight into the fabrication of cold-set gels from different protein aggregates and the generated information may provide the opportunity to develop functional food formulations enriched in plant proteins.

Rheological Properties of Mixed Gel Based on Lepidium perfoliatum seed gum and Lathyrus sativa protein isolate

Rheological Properties of Mixed Gel Based on Lepidium perfoliatum seed gum and Lathyrus sativa protein isolate

The properties and formation mechanism of oat β-glucan mixed gels with different molecular weight composition induced by high-pressure processing.

High pressure, an emerging nonthermal technology has been widely applied in food product modifications. The effects of oat β-glucan concentration and pressure on the properties of mixed gels with the different ratios of varying molecular weight (MW) β-gulcan induced by HPP were investigated. The results showed that the lowest β-glucan concentration forming a gel was 15% at 200 MPa, while 8% β-glucan was required to form a gel at 500 MPa. The gel intensity and textural properties increased with elevating β-glucan total concentration and pressure. The characteristic compact and smooth mixed gel formed with 12% β-glucan at a ratio of 50:50 at 400 MPa for 30 min. Under this optimal parameters, the mixed solution showed a relatively lower particle size and turbidity, and the hydrogen bonding and electrostatic interaction played the main role during the gel formation process by high pressure. In addition, the core molecular structure of β-glucan was maintained in the mixed gel formed under the optimal parameters.

Effect of transglutaminase on gel properties of surimi and precocious Chinese mitten crab (Eriocheir sinensis) meat

We examined the effect of transglutaminase (TG) on the gel properties of silver carp (Hypophthalmichthys molitrix) surimi in combination with different proportions (0–30%) of precocious Chinese mitten crab (Eriocheir sinensis) meat. Our results show that in the presence and absence of TG, the protein breaking force and deformation reduced significantly (P < 0.05) as the proportion of crabmeat increased. However, following incorporation of TG (0.4%), the breaking force, deformation, and unfrozen water (Wu) content were markedly increased (P < 0.05), most notably when crabmeat was absent. Moreover, with increasing proportions of crabmeat the a* (redness/greenness) and b* (yellowness/blueness) of the product increased significantly (P < 0.05), while L* (lightness) and whiteness decreased. Moreover, noticeable differences were observed between groups that contained TG compared to those that did not. Further, the concentrations of myosin heavy chain (MHC) was found to increase in the presence of crabmeat, while the addition of TG served to catalyze the formation of non-disulfide covalent bonds, thereby causing less MHC to be detected. Nevertheless, no significant change in the secondary structure (P > 0.05) of the proteins was noted, yet all gels that contained TG exhibited a more compact and regular protein network compared to those without TG. These results suggest that the addition of crabmeat may negatively impact gel formation by surimi, while the incorporation of TG may serve to improve mixed gel properties.

Effects of high-speed shear homogenization on properties and structure of the chicken myofibrillar protein and low-fat mixed gel

Effects of high-speed shear homogenization on the properties of myofibrillar protein (MP) and low-fat mixed gel were studied. The morphological structure, secondary structure, surface hydrophobicity, sulfhydryl groups and zeta potential of mixed gels were also measured. Under our experimental conditions, 14,500 rpm was the optimum speed to facilitate the gel strength, water holding capacity and G’ values of mixed gel. The fat particles evenly distributed in mixed gel and MP molecules formed a uniform network structure were the important reasons for shear homogenization treatment enhancing the properties of mixed gel. More β-sheet structure content was the underlying cause of shearing treatment to enhanced the mixed gel properties. The changes of zeta potential indicated that MP molecules were difficult to form gel by excessive shear homogenization treatment (higher than 14,500 rpm). Therefore, 14,500 rpm was the optimum shear homogenization speed to modify the structure properties, so as to achieve better gel properties of MP-fat mixed gel.

Rheological and water holding alterations in mixed gels prepared from whey proteins and rapeseed proteins

Whey proteins (WP) were replaced with rapeseed proteins (RP) at various protein mixing ratios at neutral pH and ionic strength of 150 mM. Protein gels were formed at 95 °C and another temperature of 80 °C, below the denaturation temperature of RP, to understand the importance of whether RP gelled or not for changes in rheological properties in mixed gels. Gels were analyzed for their microstructure, rheological responses (e.g. G') and water holding (maximum amount of exuded water (Amax) and ease with which water can be exuded (k)). The rheological responses obtained for mixed gels was compared to the ones of the single systems at the corresponding concentrations to understand the importance of the rheological moduli of the single systems to the modulus of the mixed gel and to enable the quantification of synergistic stiffening (S = G΄mixture/(G΄WP + G΄RP)). For gels formed at 95 °C a broader window for synergistic stiffening was formed compared to gels formed at 80 °C. Synergistic stiffening occurred when gel coarseness decreased and/or when the differences between the moduli of the individual protein gels were minimized. Water holding properties of mixed gels were tailored due to changes in the gel microstructure or due to synergistic stiffening. The behavior of k as a function of protein mixing ratio in mixed gels was similar to the behavior of gel stiffness. The decrease of k correlated well with an increase in gel stiffness. Gel coarseness and gel stiffness were inextricably linked in regards to their importance for changes in Amax.

Molecular structure and properties of κ-carrageenan-gelatin gels

Rheological studies, FTIR spectroscopy and a molecular docking approach were used to explore the structural basis of the peculiar physicochemical properties of gelatin gels modified with a κ-carrageenan admixture. Mixed gel properties are affected by the polysaccharide-to-gelatin ratio, Z, and can be divided into two categories. At low ratios, the strength of mixed gels varies insignificantly compared to gelatin due to the similar structures of the gels. Above the threshold content of κ-carrageenan (Z > 0.1), the storage modulus and yield stress of mixed gels are significantly enhanced. The nonadditivity and threshold character of the rheological properties could be the result of conformational ordering of both gelatin and κ-carrageenan, leading to the formation of additional junction zones in the gel network. According to molecular docking studies, the junctions could be formed as a result of complementary interactions between the gelatin triple helix and the κ-carrageenan double helix. The stack formation increases the interaction energy, which explains the strengthening of the gel network.

Textural behavior of gels formed by rice starch and whey protein isolate: Concentration and crosshead velocities

ABSTRACT Fabricated food gels involving the use of hydrocolloids are gaining polpularity as confectionery/convenience foods. Starch is commonly combined with a hydrocolloid (protein our polyssacharides), particularly in the food industry, since native starches generally do not have ideal properties for the preparation of food products. Therefore the texture studies of starch-protein mixtures could provide a new approach in producing starch-based food products, being thus acritical attribute that needs to be carefully adjusted to the consumer liking. This work investigated the texture and rheological properties of mixed gels of different concentrations of rice starch (15%, 17.5%, and 20%) and whey protein isolate (0%, 3%, and 6%) with different crosshead velocities (0.05, 5.0, and 10.0 mm/s) using a Box-Behnken experimental design. The samples were submitted to uniaxial compression tests with 80% deformation in order to determinate the following rheological parameters: Young’s modulus, fracture stress, fracture deformation, recoverable energy, and apparent biaxial elongational viscosity. Gels with a higher rice starch concentration that were submitted to higher test velocities were more rigid and resistant, while the whey protein isolate concentration had little influence on these properties. The gels showed a higher recoverable energy when the crosshead velocity was higher, and the apparent biaxial elongational viscosity was also influenced by this factor. Therefore, mixed gels exhibit different properties depending on the rice starch concentration and crosshead velocity.

卵白加熱ゲルの構造と物性への他成分共存の影響

We investigated the relationship between the phase separated structure and fracture properties of multicomponent gels. Specifically, we focused on the fracture properties and structure of three types of gels with different continuous phases (egg white protein (EWP) continuous, bicontinuous for both EWP and agar, and agar continuous). In addition, we revealed the effect of oil addition on EWP-agar gels with three different continuous phases. The fracture properties of mixed gels were analyzed by a large deformation test. The gel structure was also observed by confocal laser scanning microscopy and scanning electron microscopy. Results demonstrated that the continuous phase component contributed to the physical fracture properties of multicomponent gels.

Milk protein–gum tragacanth mixed gels: Effect of heat-treatment sequence

The aim of this study was to investigate the role of the heat-treatment sequence of biopolymer mixtures as a formulation parameter on the acid-induced gelation of tri-polymeric systems composed of sodium caseinate (Na-caseinate), whey protein concentrate (WPC), and gum tragacanth (GT). This was studied by applying four sequences of heat treatment: (A) co-heating all three biopolymers; (B) heating the milk-protein dispersion and the GT dispersion separately; (C) heating the dispersion containing Na-caseinate and GT together and heating whey protein alone; and (D) co-heating whey protein with GT and heating Na-caseinate alone. According to small-deformation rheological measurements, the strength of the mixed-gel network decreased in the order: C>B>D>A samples. SEM micrographs show that the network of sample C is much more homogenous, coarse and dense than sample A, while the networks of samples B and D are of intermediate density. The heat-treatment sequence of the biopolymer mixtures as a formulation parameter thus offers an opportunity to control the microstructure and rheological properties of mixed gels.

Rheological Properties of Rice Protein-Dextran Composite System

Rheological properties of rice protein-dextran composite system were studied. The formation of gel network-like structure appeared to have occurred through the interaction of rice protein and dextran at certain biopolymer concentration. An increase in the protein and/or polysaccharide concentration of the mixtures would contribute to the mechanical properties of mixed gels. The differences in fracture forces among samples as noticed in experiments also suggested the difference in microstructures.

カラギーナン混合ゼラチンゾルとゲルの特性(第4報)κ-カラギーナンおよびゼラチンの種類が牛乳添加ゲルの破断特性に及ぼす影響

カラギーナン混合ゼラチンゾルとゲルの特性(第4報)κ-カラギーナンおよびゼラチンの種類が牛乳添加ゲルの破断特性に及ぼす影響

Investigation into the preparation and stability of mixed gel soft capsules of Ephedrae herba

Objective: To investigate the method of improving the stability of Ephedrae herba soft capsules.Methods: The Ephedrae herba soft capsules were prepared by mixed gel of gelatin and hydroxypropyl methylcellulose(HPMC) as shell composition of the soft capsule in order to reduce the gelatin cross-linked reaction.The prescription and methodology of the mixed gel were optimized by central composite design.The gel properties of mixed gel were determined and the stability of mixed gel soft capsules was also studied.Results: The prescription of the mixed gel was as follows:gelatin(bloom 180 g)∶gelatin(bloom 240 g) ∶HPMC∶glycerin∶water=49∶26∶25∶30∶200.Gelling time of the mixed gel soft capsules was 5.72 min.The time limit of disintegration was 4.6 min and the time limit of accelerated 90 days was 11.2 min.Dissolution rate when accelerated 90 days was 86.6%.Conclusion: Gelatin-HPMC mixtures can improve the stability of the Ephedrae soft capsule.

Textural Properties of Beta-lactoglobulin - Sodium Alginate Mixed Gels at Large Scale Deformation.

The denaturation and gelling properties of mixed systems of β-lactoglobulin and sodium-alginate have been investigated as a function of alginate molecular weight, chemical composition, concentration, pH and ionic strength. Differential scanning calorimetry and small strain oscillatory measurements showed that denaturation temperature were lower than the gelling temperatures under the conditions examined. The denaturation temperatures were dependent on both pH and ionic strength, but unaffected by alginate concentration and type. The mechanical and textural properties of mixed gels of β-lactoglobulin and sodium alginate were dependent on several factors; the gel strength increased as a function of alginate concentration under ambient conditions, and decreased as the pH and/or the ionic strength were changed. High molecular weight alginate gave the most pronounced effects, probably due to the accessibility of the alginate for protein binding. The chemical composition of the alginate had negligible effect on the mechanical properties of the gels. PRACTICAL APPLICATIONS: As both proteins and polysaccharides are widely used in the food industry, it is important to understand the interactions between these two biopolymers in order to envisage final product properties. The present article gives an overview of several important parameters when mixing β-lactoglobulin and sodium alginate. β-Lactoglobulin is the main protein in whey and one of the major food protein ingredients. Alginate is a polysaccharide that is often used in the food industry because of its functional properties. This study shows that if the conditions and the alginate type are adequately chosen, the textural properties of food products can be controlled and tailored.

Texture Profile of Gelatin and Tea Polyphenol Mixed Gels

The effects of different factors including tea polyphenols concentration, gelatin concentration, pH and temperature on the properties of tea polyphenol/gelatin mixed gels were investigated by using texture profile analysis. The results indicated that the factors all had the influences on mixed gel properties, such as hardness, elasticity, cohesiveness, chewiness, resilience, ets.FTIR spectra verified that tea polyphenols mainly interacted with gelatin by the phenolic hydroxyl binded with reactive group of gelatin peptidyl by hydrogen in the formation of gels. Thermal stability were determined to evaluate the properties of the mixed gels by TGA analysis.

Effects of xylooligosaccharides and sugars on the functionality of porcine myofibrillar proteins during heating and frozen storage

The gel properties of mixed gels of salt-soluble proteins (SSP) and xylooligosaccharides (XOS) or other sugars were investigated. Furthermore, the water-holding capacity, synaeresis, and protein surface hydrophobicity of heated SSP/sugar mixed gels under frozen storage were evaluated. Addition of XOS and sugars lowered expressible moisture and thus elevated the water-holding capacity of mixed gels. The protein surface hydrophobicity (RSo) of heated (71.1 °C) XOS-added gels was lower than that of other treatments, indicating possible lower exposure of protein hydrophobic groups. Results from freeze/thaw stability and protein solubility showed a descending pattern of SSP/sugar mixed gels during frozen storage, with XOS-added gels being better in both test items than other treatments. Increasing saccharide levels improved freeze/thaw stability and protein solubility of frozen mixed gels. Addition of xylooligosaccharides resulted in the lowest RSo among treatments and appears to impact better cryoprotective function to meat proteins than other sugars.