Search results for "Calcium alginate"
showing 10 items of 15 documents
Encapsulation of black mulberry microcuttings: studies on capsules and synthetic seeds
2017
The encapsulation technology for plant tissue culture can be an efficient tool to optimize the plant management systems and to preserve valuable plant germplasm. In this paper, two experiments were carried out to evaluate the encapsulation efficiency in mulberry (Morus nigra L.). In the first experiment, gel capsules were stored at 4°C for different times (0, 30, 90, 180 and 360 days). The highest percentage of shoot viability (82.5%) and regrowth (72.5%) was scored after 180 days of storage, with an average development of 2.5 shoots/capsule. The second experiment was aimed to point out an efficient protocol to turn the capsules of black mulberry in synthetic seeds ready to develop into who…
Aqueous two-phase system cold-set gelation using natural and recombinant probiotic lactic acid bacteria as a gelling agent
2016
The present study aimed to entrap probiotic lactic acid bacteria (LAB) in a sodium alginate and sodium caseinate aqueous two-phase gel system. The natural acidifying properties of two therapeutic probiotic LAB were exploited to liberate calcium ions progressively from calcium carbonate (CaCO3), which caused the gelation of the co-existing phases. Bi-biopolymeric matrix gelation of GDL/CaCO3 or LAB/CaCO3 was monitored by dynamic rheological measurements, and the final gels were characterized by frequency dependence measurements and confocal laser scanning microscopy. Weak to strong gels were formed with an elastic modulus G' from 10 to 1.000Pa, respectively. After cold-set gelation of our sy…
Localization of Lactococcus lactis ssp lactis bv diacetylactis in alginate gel beads affects biomass density and synthesis of several enzymes involve…
1993
Lactococcus lactis ssp lactis bv diacetylactis, immobilized in calcium alginate beads, was grown in synthetic medium in a continuous flow reactor. Cell distribution inside the gel, as well as the activity of various enzymes, was measured after 30 h of operation. The included biomass tended to concentrate at the periphery of the bead along a section of radius about 100 μm long. ATPase activity was maximal in this zone. The activity of NADH oxidase, alcohol dehydrogenase, diacetyl reductase and acetoin reductase, which are repressed in the presence of citrate, were higher in the deeper zones than at the surface of the beads. This result shows that only the peripheral zone of the bead is respo…
Cream fermentation by a mixed culture of lactococci entrapped in two-layer calcium alginate gel beads
1992
This investigation was directed towards the development of a process which produces a fermented cream of greatly reduced cell number.Lactococcus lactis subsp.Lactis andLactococcus lactis subsp.lactis biovardiacetylactis were entrapped separately in normal or two-layer Ca-alginate gel beads. Pasteurized cream (31% fat content) was inoculated with free-cells and with normal or two-layer beads. When 8% of the total volume was occupied by the gel, there was 300–800 times more inoculum in this system and the fermentation time was considerably reduced (5h against 18h). When pH 5.0 was reached, the residual free-cell count was 150 and 1800 times less than for a classical inoculation method with fr…
Modeling of continuous Ph-stat stirred tank reactor withLactococcus lactisssp.lactisbv.diacetylactisimmobilized in calcium alginate gel beads
1995
A dynamic diffusion-reaction-growth model is proposed for the study of lactic fermentation, the bioconversion of citric acid, and cell release in an immobilized cell reactor [pH-stat continuous stirred tank-reactor (CSTR)]. The model correctly simulates the onset of fermentation and colonization of the gel, followed by the steady state. External diffusion is nonlimiting and internal diffusion is limited by high cell densities at the periphery of the gel beads. Lactose-citrate cometabolism in the gel is related to the distribution of active included biomass within the gel and to gradients of substrates (lactose, citrate) and products (lactate, pH) in the beads. The utilization of lactose is …
Pb(II) adsorption by a novel activated carbon - alginate composite material. A kinetic and equilibrium study.
2016
The adsorption capacity of an activated carbon – calcium alginate composite material (ACAA-Ca) has been tested with the aim of developing a new and more efficient adsorbent material to remove Pb(II) ion from aqueous solution. The study was carried out at pH = 5, in NaCl medium and in the ionic strength range 0.1–0.75 mol L−1. Differential Pulse Anodic Stripping Voltammetry (DP-ASV) technique was used to check the amount of Pb(II) ion removed during kinetic and equilibrium experiments. Different kinetic (pseudo first order, pseudo second order and Vermuelen) and equilibrium (Langmuir and Freundlich) models were used to fit experimental data, and were statistically compared. Calcium alginate …
Kinetic and equilibrium study for cadmium and copper removal from aqueous solutions by sorption onto mixed alginate/pectin gel beads
2013
Abstract Kinetic and equilibrium studies have been carried out to evaluate Cd(II) and Cu(II) sorption from aqueous solution by calcium alginate and new synthesized hybrid calcium alginate/pectate gel beads with different alginate/pectate concentration ratios. Physical and chemical properties of the beads were characterized by different techniques (SEM, EDX, TGA). The best experimental pH conditions were selected on the basis of a study on the acid–base properties of pectin and alginate in aqueous solution and their ability to act as sequestering agents for copper(II) and cadmium(II) ions. Calcium released during the sorption process was determined in order to elucidate a possible ion exchan…
Enhancement of adsorption ability of calcium alginate gel beads towards Pd(II) ion. A kinetic and equilibrium study on hybrid Laponite and Montmorill…
2015
Abstract The adsorption ability of hybrid Montmorillonite and Laponite–calcium alginate gel beads towards Pd 2 + ion was studied in the pH range 2–4, in pure water and in aqueous NaCl solution at I = 0.01 mol L − 1 and T = 25 °C. The pseudo second order kinetic equation and the Langmuir and Freundlich isotherms were used to fit the kinetic and thermodynamic experimental data. A comparison of the results already published on the adsorption capacity of calcium alginate gel beads at the same experimental conditions was made. Enhancement of palladium(II) adsorption by alginate beads with the addition of the two clay minerals was obtained, with increments higher than 50% of Pd(II) ion recovered/…
Mercury(II) removal from aqueous solution by sorption onto alginate, pectate and polygalacturonate calcium gel beads. A kinetic and speciation based …
2013
Abstract Gel beads of calcium alginate, pectate and polygalacturonate salts have been tested as sorbent materials for mercury(II) removal from aqueous solutions. Physico-chemical properties of gel beads, defined by SEM–EDX, TGA and texture and density analysis, were correlated with gel beads sorption capacity towards Hg 2+ ion. A speciation study in aqueous solution was carried out to define the strength of interaction of mercury ion with the polymers investigated and to assess the more suitable experimental conditions to achieve the best effectiveness of Hg 2+ sorption by gel beads. On the basis of the speciation study, pH values in the 3–5.5 pH range were considered appropriated for mercu…
Sorption of Pd(II) ion by calcium alginate gel beads at different chloride concentrations and pH. A kinetic and equilibrium study
2016
Abstract A kinetic and thermodynamic study on the sorption ability of calcium alginate gel beads towards Pd(II) ion was made in aqueous solution at different pH and chloride concentrations. The experimental conditions adopted in the sorption experiments were established on the basis of a speciation study on the Pd 2+ -AA system in which all the side reactions, such as the hydrolysis of Pd(II), the protonation of alginate and the interactions of the ligand and the metal ion with ions of ionic medium were taken into account. In the pH range 2–5 and at chloride concentration in the range 0 ⩽ C Cl - /mmol L −1 ⩽ 10 the gel beads showed good sorption ability towards Pd(II) ion as confirmed by k…