Mixed Gels Research Articles

Evaluation of the antibacterial activity of Lactobacilli probiotics supernatants against Enterococcus faecalis (in-vitro study)

BackgroundThere is an increasing demand to find a potent antibacterial agent against endodontic pathogens with the least toxic effect. The study aimed to evaluate the antibacterial activity of Lactobacilli probiotics on Enterococcus faecalis (E. faecalis) in comparison to calcium hydroxide paste.MethodsThe study involved two stages; (stage one): determination of the antibacterial properties of three strains of Lactobacilli probiotics supernatants (PS); Lactobacillus plantarum, Lactobacillus rhamnosus, Lactobacillus acidophilus, and a cocktail mix of the three supernatants against E. faecalis using agar well diffusion method in both solution and gel phase. The formed zones of inhibition (ZOI) were measured in millimeters (mm) and compared to each other. PS solution and gel of the largest ZOI were further compared with calcium hydroxide paste (35% Ultra Cal XS Ca(OH)2) This was followed by (stage two): assessment of the minimum inhibitory concentration (MIC) of the PS that showed the largest ZOI against E. faecalis by agar well diffusion assay for both PS solution and gel.ResultsAll supernatants showed growth inhibition against E. faecalis, and the cocktail mix showed the largest ZOI. However, no significant difference was found between the supernatants in both the solution and gel phases (p > 0.05). Ca(OH)2 showed a significantly lower effect than both the cocktail mix solution and gel (p < 0.05). The MIC of the cocktail mix solution and gel against E. faecalis was 50 mg/ml. (p > 0.05).ConclusionPS has an antibacterial effect on E. faecalis and was more effective than Ca(OH)2.Lactobacilli probiotics could be a promising antibacterial agent used as an irrigant or an intracanal medication.

Gellan gum improves the gel properties and thermal stability of tilapia ( Oreochromis spp.) skin gelatin sterilized at 121°C

The gel strength and thermal stability of fish gelatin are poorer than mammal gelatin. It's very important to improve the thermal stability which can sustain autoclave sterilization so as to expand the application of fish gelatin. In this study, 10% (w/v) tilapia skin gelatin sols with or without 1% (w/v) low acyl gellan gum were sterilized at 121°C before gelation, and the effects of autoclave sterilization on the textural properties and gel structures were investigated. The results showed that autoclave sterilization decreased the hardness (from 661.8 g to 505 g) and chewiness (from 27.44 mJ to 20.33 mJ) of the gels, which were raised more than four times by gellan gum. The gel point and melting point were increased from 16.7°C and 24.3°C to 40°C and 57°C respectively by gellan gum, both of which could sustain autoclave sterilization. Autoclave sterilization significantly decreased the relative intensity of the secondary structures and increased the interaction between proteins and water. The polypeptide chains in fish gelatin formed spherical aggregates and further formed a spatial network structure, which was destroyed by autoclave sterilization. Gellan gum prevented the damage by forming a continuous phase of a tight network that could sustain autoclave sterilization. So gellan gum strengthened the gelatin network and further increased the gel strength and gel point of the mixed gel. Novelty impact statement The gel point and melting point of tilapia skin gelatin were lower than room temperature, which limited its application. Gellan gum significantly improved the gel properties and thermal stability of tilapia skin gelatin, both of which could sustain autoclave sterilization. Gellan gum formed a continuous phase of a tight network in the mixed gel, which strengthened the gel structures and would not be damaged by autoclave sterilization.

Improving 3D printability of pumpkin pastes by addition of surimi

In the field of food 3D printing, the printable range of pumpkin powder is small, and the printing research on natural food protein and polysaccharide systems is very rare. Therefore, the feasibility of improving the 3D printing properties of pumpkin paste by adding surimi was investigated. The effects of surimi content in the range of 2%–17% (w/w) on the water distribution, rheological properties, 3D printing accuracy and stability, water-holding capacity, and texture of 3D printed composite slurries were determined. The composite gel containing 2% (w/w) surimi has suitable storage and loss moduli with higher water retention properties. This composite gel exhibits higher 3D printing accuracy, support performance, and fidelity. What's more, the texture properties of its 3D printed samples are suitable for people with dysphagia. On the other hand, the slurry containing 12% (w/w) surimi exhibited the worst support performance due to the high mobile water content and the 3D printed samples also had the worst texture. Practical applications With people's pursuit of healthy and nutritious diet, we found that adding 2% (w/w) surimi can functionally replace additives to improve the printable range of pumpkin powder, and the mixed gel system as this content has better supporting ability and printing accuracy.

Mixing plant-based proteins: Gel properties of hemp, pea, lentil proteins and their binary mixtures

One of the challenges in substituting dairy products by alternative proteins is that the properties of mixed protein gels cannot necessarily be predicted by those of single protein gels, whereas the need of mixing is often driven by nutritional aspects. However, mixing plant proteins could also open a door to new textures.The main goal of this study was to investigate the impact of binary mixing of hemp (H), yellow pea (P), and brown lentil (L) protein concentrates/isolates on their gel and water-holding properties. Dispersions of reconstituted proteins and mixtures thereof were gelled using glucono-δ-lactone (GDL), transglutaminase (TG), and temperature (T) at a protein content of 12% (w/w).Mixtures of pea and lentil proteins showed gel strengths for TG- and T-induced gels that are proportional to the ratio of the mixture constituents (linear mixing behavior), whereas synergistic effects were observed for GDL-induced gelation. In contrast, all mixtures containing hemp exhibited a non-linear mixing behavior for the three gelation methods, usually resulting in lower gel strengths compared to theoretically expected values.The study showed that mixing plant-based proteins of different protein sources can lead to very different mixing behaviors in terms of gel properties, showing either a reinforcing, an indifferent or a weakening effect compared to the theoretically expected properties. The results can help developing more targeted plant protein-based soft gel products such as yogurt alternatives with specific techno-functional properties, while adjusting the nutritional characteristics.

Shaping gels and gels mixture to create helices

In cooking, food gels, such as agar-agar or alginate, are often prepared and presented in the form of spheres or spaghetti. While experimenting in our kitchen, we realized that it is quite difficult to make more advanced shapes. In this study, we sought to develop new methods to obtain more complex shapes. Our first challenge was to obtain helices. The best method we selected was to deposit the solutions before their gelation in a thread. The robustness of the method is tested by systematically changing the thread pitch, diameter, and depth. From the deformation under its own weight, we propose to deduce the mechanical characteristics of the helix. These values are compared to those obtained in the laboratory using indentation testing. Finally, we experimented with mixed gels obtained by combining agar-agar and alginate.

In vitro digestion of a mixed gel of pork muscle and resistant starch: Salt-soluble protein perspective

The in vitro digestion of a mixed gel (MS) of pork muscle and resistant starch (RS) was investigated and the role of the salt-soluble protein (SSP) in the function promotion of the mixed gel was clarified. The results showed that the mixed muscle gel (MS) and the addition of RS to muscle gel (M + S) presented an improved protein digestion, as indicated by a reduced particle size of the hydrolysates, more degradation of proteins with large molecular weight and more generation of free amino acids compared with the RS-free muscle gel (M). Meanwhile, the hydrolysates of the M + S and MS showed intensified DPPH radical scavenging activities. Specifically, the MS exerted preferable properties in protein digestion and antioxidant activity. Similar digestion characteristics were noticed in mixed SSP gels.The current study revealed that the reinforced functionality of the mixed muscle gel was associated with the binding relationships between SSP and RS during cooking.

Gel properties and interactions of scallop (Patinopecten yessoensis) male gonad hydrolysates and nonionic polysaccharide mixtures

The involvement of hydrogen bonding and hydrophobic interactions in a mixture of scallop (Patinopecten yessoensis) male gonad hydrolysates (SMGHs) and guar gum (GG) or locust-bean gum (LBG) was investigated using guanidine hydrochloride (GuHCl) and urea treatments in this study. The addition of GG and LBG (5.56 mg/mL) increased the viscosity of SMGHs at 0.1 s-1 by almost 2.5-fold and 1.7-fold, respectively, reaching 254.8 and 177.0 Pa·s. After treatment with GuHCl or urea, the mixed gels (SMGHs/GG and SMGHs/LBG) became relatively transparent and more fluid, as the viscosity significantly reduced. Moreover, changes of moisture distribution and conformational characteristics suggested that hydrogen bonding and hydrophobic interactions were the main intermolecular forces in the mixed gels of SMGHs and GG or LBG. Furthermore, the SMGHs/GG and SMGHs/LBG mixtures yielded strong gels with viscous network structures, indicating that these materials can be used as thickening agents in food systems.

Two-Phase Medium – A New Approach to Microbiological Culturing

We tested a new two-phase culture medium for culturing microorganisms, in particular algae and fungi. In media composed of mixed gel and solid phases of granite, basalt, sandstone, limestone and sodium glass, we observed the growth of selected species inhabiting the boundaries of the gel medium with the solid phase. The species used were Klebsormidium dissectum (F.Gay) H.Ettl & Gärtner, Vischeria polyphem (Pitschmann) Kryvenda, Rybalka, Wolf & Friedl and Muriella decolor Vischer (algae); and Aspergillus tubingensis R.Mosseray, Aureobasidium pullulans (de Bary) G.Arnaud, Chaetomium globosum Kunze and Penicillium sp. Link (fungi). In the six-weeks period of parallel cultures, the growth rate of the algae inoculum in two-phase media was twice that observed in the control culture (gel medium). The algae also maintained high viability in the new medium.

Engineering Emulsion Gels as Functional Colloids Emphasizing Food Applications: A Review.

Gels are functional materials with well-defined structures (three-dimensional networks) assembled from the dispersed colloids, and capable of containing a large amount of water, oil, or air (by replacing the liquid within the gel pores), known as a hydrogel, oleogel, and aerogel, respectively. An emulsion gel is a gelled matrix filled with emulsion dispersion in which at least one phase, either continuous phase or dispersed phase forms spatial networks leading to the formation of a semisolid texture. Recently, the interest in the application of gels as functional colloids has attracted great attention in the food industry due to their tunable morphology and microstructure, promising physicochemical, mechanical, and functional properties, and superior stability, as well as controlled release, features for the encapsulated bioactive compounds. This article covers recent research progress on functional colloids (emulsion gels), including their fabrication, classification (protein-, polysaccharide-, and mixed emulsion gels), and properties specifically those related to the gel-body interactions (texture perception, digestion, and absorption), and industrial applications. The emerging applications, including encapsulation and controlled release, texture design and modification, fat replacement, and probiotics delivery are summarized. A summary of future perspectives to promote emulsion gels' use as functional colloids and delivery systems for scouting potential new applications in the food industry is also proposed. Emulsion gels are promising colloids being used to tailor breakdown behavior and sensory perception of food, as well as for the processing, transportation, and targeted release of food additives, functional ingredients, and bioactive substances with flexibility in designing structural and functional parameters.

Modulation of Metabolome and Overall Perception of Pea Protein-Based Gels Fermented with Various Synthetic Microbial Consortia.

Moving to a more sustainable food system requires increasing the proportion of plant protein in our diet. Fermentation of plant product could thus be used to develop innovative and tasty food products. We investigated the impact of fermentation by synthetic microbial consortia (SMC) on the perception of pea protein-based gels, giving possible keys to better understand the origin of sensory perception (e.g., beany, bitter). Two types of pea gels, containing (i) 100% pea proteins and (ii) 50% pea proteins/50% milk proteins, were fermented with three different SMC. Major species developing in both types of gels were Geotrichum candidum, Lactococcus lactis, and Lactobacillus rhamnosus. In pea gels, sensory analyses revealed that bitterness increased after fermentation, which could be due to hydrophobic amino acids resulting from protein hydrolysis, but also decreased pea note intensity in pea gels. In mixed gels, pea perception was similar whatever the SMC, whereas cheesy perception increased. Olfactometry experiments revealed that some specific “green” aroma compounds, responsible for green off-note, were suppressed/reduced by fermentation. The data presented investigated to which extent the design of SMC, together with gels composition (pea gels versus mixed gels), could modulate sensorial perception and drive consumer acceptability.

Influence of Levan on the Thermally Induced Gel Formation of β-Lactoglobulin

In this study, the influence of levan on the phase behavior and the thermally induced gelation of the mixed β-lactoglobulin—levan gels as a function of polymer content, molecular weight and ionic strength was characterized. For this purpose, rheology was used to study the mechanical properties of the gels and the water binding of the network structure was investigated by time domain nuclear magnetic resonance. Phase behavior and network type were analyzed by optical observation and electron microscopy. Levan enhanced the aggregation and gel formation of β-lg due to segregative forces between the polymer species. Segregation was caused by the excluded volume effect and was more pronounced at lower ionic strength, higher levan contents and higher levan molecular weights. The presence of levan increased the water binding of the gel networks. However, this effect decreased with increasing levan content. At high ionic strength and high levan content, phase separated gels were formed. While segregative forces enhanced network formation, and therefore, increased the gel strength of mixed gels at low ionic strength, levan had also antagonistic effects on the network formation at high ionic strength and high polymer contents.

THE EFFECTIVENESS OF GUAVA (Psidium guajava) AND SENDUDUK LEAVES (Melastoma malabathricum L.) EXTRACT GEL TOWARDS THE INFLAMMATION MARKERS AND COLLAGENS ON INDUCED MALE RATS (SPRAGUE DAWLEY) WITH DIABETES

This study aimed to measure the effectiveness of a mixed extract gel from Melastoma malabathricum L. (ML) and Psidium guajava leaves (PG) on inflammatory markers and collagen distribution wound tissue in rats (Sprague Dawley) induced with diabetes. This was an experimental study with a randomized block design to 20 male rats divided into 4 treatment groups. Group 1 is negative control (gel blank), Group 2 is positive control (clindamycin gel), Group 3 used 4% gel formula mixture of ML + PG leaves, and Group 4 used 6% gel formula, a mixture of ML + PG leaves extract the gel. The results showed that there was a significant difference (p&lt;0.001) in total Tumor Necrosis Factor-alpha (TNF-α) treated with 6% extract gel (ML + PG) from a level of 25.0 pg/mL on the 2nd day to 1.68 pg/mL on the 6th day. The smallest wound diameter was 0.75 mm2 as observed on the 6th day in rats treated with 6% extract gel (ML + PG). The largest distribution of collagen area was 219,8 (86,2%) treated by 6% extract gel (ML + PG).

Textural characteristics of mixed gels improved by structural recombination and the formation of hydrogen bonds between curdlan and carrageenan

The physicochemical properties of a single gel are strongly affected by an admixture of another ingredient as a cosolvent. Although many studies have proposed the gelation mechanism of mixed gels using scattering, spectroscopic, thermal, and rheological techniques, direct evidence at the molecular scale is still lacking. As molecular models, carrageenan and curdlan are linear polysaccharides suitable for studying gelation mechanisms of mixed gels. In this study, based on texture profile analysis and fourier transform infrared spectroscopy, we divided mixed gels into three stages. In stage 1, carrageenan molecules were dispersed into the dissociated curdlan matrix and improved the curdlan gel network. In stage 2, the dissociated curdlan competed with carrageenan for water molecules preventing the formation of single gel or mixed gels, causing the decreased textural parameters. In stage 3, owing to structural recombination and the formation of hydrogen bonds between curdlan and carrageenan, a denser gel was formed. X-ray diffraction results showed that at curdlan: carrageenan ratios from 1:1–1:3, the crystalline peak of carrageenan appeared near 2θ = 28.5° and the peak of curdlan disappeared at 2θ = 19.5°, indicating that the dissociated curdlan destroyed the original crystalline domains of curdlan and dispersed into the carrageenan matrix. Scanning electron microscopic analysis revealed that at a curdlan: carrageenan ratio of 1:3, shorter and smaller junction zones facilitated a considerably more compact and dense structure. Based on molecular docking, curdlan was found to dissociate into a single helical chain, bonding with double- or single-helical carrageenan. Thus, structural recombination and new intermolecular hydrogen bonds between curdlan and carrageenan afforded considerably short and small junction zones.

Synthesis of Fibrin-Type I Collagen Biomaterials via an Acidic Gel.

Fibrin-Type I collagen composite gels have been widely studied as biomaterials, in which both networks are usually formed simultaneously at a neutral pH. Here, we describe a new protocol in which mixed concentrated solutions of collagen and fibrinogen were first incubated at acidic pH to induce fibrinogen gel formation, followed by a pH change to neutral inducing collagen fiber formation. Thrombin was then added to form fibrin-collagen networks. Using this protocol, mixed gels containing 20 mg.mL−1 fibrin and up to 10 mg.mL−1 collagen could be prepared. Macroscopic observations evidenced that increasing the content of collagen increases the turbidity of the gels and decreases their shrinkage during the fibrinogen-to-fibrin conversion. The presence of collagen had a minor influence on the rheological properties of the gels. Electron microscopy allowed for observation of collagen fibers within the fibrin network. 2D cultures of C2C12 myoblasts on mixed gels revealed that the presence of collagen favors proliferation and local alignment of the cells. However, it interferes with cell differentiation and myotube formation, suggesting that further control of in-gel collagen self-assembly is required to elaborate fully functional biomaterials.

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.

Influence of Soybean Dietary Fiber on the properties of Konjac Glucomannan/κ-Carrageenan Corn Oil Composite Gel

The effects of soybean dietary fiber (SDF) on the gel properties of konjac glucomannan/κ-carrageenan (KGM/κ-CA) were assessed. The addition of SDF significantly changed the color of KGM/κ-CA composite gel, which was mainly expressed as an increment in whiteness. SDF improved the hardness and chewiness of the KGM/κ-CA composite gels. The KGM/κ-CA composite gel with SDF had better water- and oil-holding capacities due to the porous structures produced by SDF in the gels. SDF formed a spatial framework with KGM and κ-CA, it supported the internal structure of the gel, and it disrupted the cohesive structure of the systems, thus leading to an uneven gel structure. The existence of SDF significantly enhanced the melting temperature and thermal stability of the mixed gels. Based on the results of the frequency sweep it can be concluded that SDF increased the storage modulus of the mixed gels and stimulated the formation of more resilient gel structures. The result of steady shear rheology revealed that SDF increased the apparent viscosity of the mixed gel system. In general, the addition of SDF could improve optical, mechanical, and thermodynamic properties when using KGM and κ-CA to simulate solid fat. The results of this study had certain guiding significance and reference value for the development of solid fat products simulated by SDF/KGM/κ-CA composite gel.

Soy and whey protein isolate mixture/calcium chloride thermally induced emulsion gels: Rheological properties and digestive characteristics

We present the preparation and physicochemical properties of thermally induced emulsion gels of a soy protein isolate–whey protein isolate (SPI–WPI)/calcium chloride composite, and the analysis of their nutrient release behaviors using fat-soluble vitamin E as a model system by simulating its digestion in vitro. In general, the SPI–WPI composite emulsion gel was found to have better water-holding capacity and texture than the emulsion gels formed by the single protein. The microstructure and rheological properties of the gel suggested that the CaCl2 concentration significantly influences the fundamental structure and mechanical properties of the SPI–WPI gel. The in vitro digestion experiments revealed that the mixed protein emulsion gel improves the bioavailability of vitamin E. This study is of great significance in the utilization of these natural emulsifiers, as they can be used in the development of emulsion delivery systems for lipophilic nutrients and other health products.

Development of Products Based on a Combination of Animal and Plant Proteins

The article provides information on the possibility of combining products of animal and plant origin in one functional system. The design of model minced meat is based on a balanced complex of basic nutrients and ballast substances, vitamins, and has high nutritional and taste properties. The formation of the structure consists in increasing the strength of mixed protein gels, increasing the fat and water retention capacity of minced meat together with biologically active additives (wheat germ, Mobi-Lux universal additive, kelp and fucus), which create specific characteristics, flavor notes based on biopolymers of the food matrix. The types of dietary supplements and their dosages have been determined. The functional properties of the cutlet mass have been adjusted.

The Effect of Salt on the Gelling Properties and Protein Phosphorylation of Surimi-Crabmeat Mixed Gels.

The effects of different salt additions (1.0%, 1.5%, 2.0%, 2.5%, 3.0%, and 3.5%) on the gelling properties and protein phosphorylation of the mixed gels (MG) formed by silver carp (Hypophthalmichthys molitrix) surimi with 10% crabmeat were investigated. The MG’s breaking force, deformation, gel strength, and water-holding capacity (WHC) increased as the salt concentration increased. The intrinsic fluorescence intensity of the samples initially decreased and then increased, reaching the lowest when the NaCl concentration was 2.5%. The result of SDS–polyacrylamide gel electrophoresis indicated that large aggregates were formed by protein–protein interaction in the MG containing 2.5% or 3.0% NaCl, decreasing the protein band intensity. It was also found that with the addition of NaCl, the phosphorus content initially increased and then decreased, reaching the maximum when the NaCl concentration was 2% or 2.5%, which was similar to the changing trend of actin band intensity reported in the results of Western blot. These results revealed that the amount of salt used had a significant effect on the degree of phosphorylation of the MG protein. The increase in phosphorylation was linked to improved gelling properties, which could lead to new ideas for manufacturing low-salt surimi products in the future.

Effect of bacterial cellulose nanofibers incorporation on acid-induced casein gels: microstructures and rheological properties

Abstract In this study, the effect of bacterial cellulose nanofibers (BCNF) incorporation on the structural and rheological properties of casein gels was investigated, where the mixed BCNF and casein gels were prepared by adding gluconic acid δ-lactone (GDL) to acidify the mixed polymer solutions at 3.0% casein concentration (w/v) and varying BCNF concentrations (0–0.5%, w/v). By changing the addition amount of GDL, the mechanical and structural properties of the mixed gels were studied at above, near and below the electric point (pI) of the casein. At pH above the pI of the casein, the introduction of BCNF initially increased the gel strength, but further addition of BCNF weakened the mixed gels. At near and below the pI of the casein, the incorporation of BCNF continuously increased the gel strength. Besides, all gels showed good structural homogeneity, without macroscopic phase separation occurring, which indicated good compatibility of BCNF with the casein gels.