Development and characterization of self-healing gel temporary plugging agent for well killing

Influence of immobilization of bacteria, yeasts and fungal spores on the mechanical properties of agar and alginate gels

The aim of this study was to investigate the modification of mechanical, rheological, and sensory properties of chickpea pastes and gels by incorporating other ingredients (olive oil or quinoa flour), to develop plant-based alternatives that meet consumer demands for healthy, natural, and enjoyable food products. The pastes and gels were made with different amounts of chickpea flour (9% and 12%, respectively). For each product, a first set of products with different oil content and a second set with quinoa flour (either added or replaced) were produced. The viscoelastic properties of the pastes and the mechanical properties of the gels were measured. Sensory evaluation and preference assessment were carried out with 100 participants using ranking tests. The study found remarkable differences in rheological, mechanical, and sensory properties of chickpea products upon the inclusion of oil and quinoa flour. The addition of oil increased the viscosity and decreased the elastic contribution to the viscoelasticity of the pastes, while it improved the firmness and plasticity in gels. It also increased the creaminess and preference of both pastes and gels. Replacing chickpea with quinoa flour resulted in less viscous pastes and gels with less firmness and more plasticity. In terms of sensory properties, the use of quinoa as a replacement ingredient resulted in less lumpiness in the chickpea paste and less consistency and more creaminess in both the pastes and gels, which had a positive effect on preference. The addition of quinoa increased the viscosity of pastes and the firmness and stiffness of gels. It increased the consistency and creaminess of both pastes and gels. Quinoa flour and/or olive oil are suitable ingredients in the formulation of chickpea-based products. They contribute to the structure of the system, providing different textural properties that improve acceptance.

The mechanical properties of fibrin and protofibrin gels in the presence of physiologic levels of Ca(II) and Zn(II) are described. As monitored with a thrombelastograph, Ca(II) (0.5-2 mM) increases the rate of development and the maximum level of gel elastic modulus (G) of fibrin and protofibrin gels. Zn(II) (10-50 microM) decreases the elastic modulus of those gels, even in the presence of a large excess of Ca(II). This contrasts with the ability of both divalent cations to increase fibrin and protofibrin gel turbidity. Unlike the turbidity or fibre thickness of fibrin and protofibrin gels, both of which are increased by these cations, gel elasticity is increased by Ca(II) but decreased by Zn(II). It is demonstrated that Ca(II) and Zn(II) modulate fibrin and protofibrin gels independently of one another, and that they have opposing effects on the mechanical properties of the gels. The disparity between the visual (turbidity, TEM) and the mechanical (elasticity) properties of (proto)fibrin gels indicates the need for new conceptual and analytic paradigms.

Starch gelatinization inside a whey protein gel formed by cold gelation

We explore the phase diagram and mechanical properties of molecular gels produced from mixing water with a dimethyl sulfoxide (DMSO) solution of the aromatic dipeptide derivative fluorenylmethoxycarbonyl-diphenylalanine (Fmoc-FF). Highly soluble in DMSO, Fmoc-FF assembles into fibrous networks that form gels upon addition of water. At high water concentrations, rigid gels can be formed at Fmoc-FF concentrations as low as 0.01 wt %. The conditions are established defining the Fmoc-FF and water concentrations at which gels are formed. Below the gel boundary, the solutions are clear and colorless and have long-term stability. Above the gel boundary, gels are formed with increasing rapidity with increasing water or Fmoc-FF concentrations. A systematic characterization of the effect of Fmoc-FF and water concentrations on the mechanical properties of the gels is presented, demonstrating that the elastic behavior of the gels follows a specific, robust scaling with Fmoc-FF volume fraction. Furthermore, we characterize the kinetics of gelation and demonstrate that these gels are reversible in the sense that they can be disrupted mechanically and rebuild strength over time.

Effect of the conformation of gelatin macromolecules on mechanical properties of gels and films

Mechanical properties of composite gels consisting of fractionated whey proteins and fractionated milk fat

Thermoreversible gelation of mixed triblock and diblock copolymers in n-octane

Changes with retrogradation of mechanical and textural properties of gels from various starches

Polymer gels have been widely used in the field for tissue engineering, sensing, and drug delivery due to their excellent biocompatibility, hydrophilicity, and degradability. However, common polymer gels are easily deformed on account of their relatively weak mechanical properties, thereby hindering their application fields, as well as shortening their service life. The incorporation of reversible non-covalent bonds is capable of improving the mechanical properties of polymer gels. Thus, here, a poly(methyl methacrylate) polymer network was prepared by introducing host–guest interactions between pillar[5]arene and pyridine cation. Owing to the incorporated host–guest interactions, the modified polymer gels exhibited extraordinary mechanical properties according to the results of the tensile tests. In addition, the influence of the host–guest interaction on the mechanical properties of the gels was also proved by rheological experiments and swelling experiments.

ABSTRACTTo relate to mechanical and sensory properties of soft gels, electromyography (EMG) of the suprahyoid musculature during palatal reduction (i.e., compression between the tongue and the hard palate) followed by normal swallowing was investigated. EMG was recorded using healthy adults as subjects to monitor the activities of the masseter muscle and the suprahyoid musculature during oral processing. Mechanical properties of gels were examined by compression tests at various strains and deformation rates. The duration of oral processing was prolonged and the EMG activity of the suprahyoid musculature increased with increasing concentration of gelling agents. The EMG activity of the suprahyoid musculature correlated well with the compression load of gels at extremely large strains (e.g., 90% strain) and with sensory perceived hardness. The EMG activity of the suprahyoid musculature is an effective parameter in analyzing human oral processing of soft gels and is deducible objectively by compression load at large strains.PRACTICAL APPLICATIONSTexture design of nursing‐care foods is important challenges in the food industry, as there is an increasing demand with increasing number of people with difficulties in mastication and/or swallowing in this aged society. The electromyography (EMG) activity of the suprahyoid musculature can be used as an objective parameter to analyze eating behavior of soft gels that are broken down through palatal reduction without chewing before swallowing. Surface EMG provides food manufactures with a strategy for the texture design of nursing‐care foods because soft gels are the base of these food products.

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.

Mechanical characterization of active poly(vinyl alcohol)–poly(acrylic acid) gel

Ternary macromolecular gels made from propylene carbonate including an inorganic salt. Influence of the salt on mechanical properties of such gels

The thermoreversible gelation of three triblock copolymers polystyrene−b-poly(ethylene/butylene)−b-polystyrene, with different molar masses and a similar chemical composition, in n-octane was studied. The solvent is selective for the middle poly(ethylene/butylene) block of the copolymers. The influence of the molar mass of the copolymer on the sol−gel transition and on the mechanical properties of the gels was analyzed. The sol−gel transition temperature increased with the copolymer concentration and the copolymer molar mass. The mechanical properties of the different gels were examined through oscillatory shear and compressive stress relaxation measurements. The concentration dependence of the elastic storage modulus was established with an exponent close to that expected for systems in good solvents (2.25) that possess a structure similar to that of chemical networks. The experimental data of the three copolymers fit a sole straight line in a double-logarithmic scale. The relaxation rates observed were high for the copolymers with lower molar masses, indicating a considerable mobility in the gel over the measurement time. The relaxation rate decreased as the copolymer molar mass increased. Some of the copolymer gels examined exhibited some elasticity, allowing reversible deformation. The degree of elastic response of SEBS gels increased the higher the gelation temperature of the gel was, that is, the longer the lifetime of the gel junctions was.