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Cveto Klofutar - One of the best experts on this subject based on the ideXlab platform.
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viscosities and apparent specific volumes of Pectic Acid and its lithium salt in aqueous solutions
Food Hydrocolloids, 1998Co-Authors: Helena Abramovic, Cveto KlofutarAbstract:Abstract From commercially available apple pectin, Pectic Acid was isolated by alkaline catalysed hydrolysis and physico-chemically characterised. The densities and viscosities of aqueous solutions of Pectic Acid and its lithium salt were determined at concentrations up to 0.016 g cm −3 . The effect of the addition of simple salt and the degree of neutralisation on the apparent specific volume and on the limiting viscosity number of dilute aqueous solutions of Pectic Acid and its lithium salt was investigated
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conductivity of some tetra n alkylammonium salts of Pectic Acid
European Polymer Journal, 1997Co-Authors: Helena Abramovic, Cveto KlofutarAbstract:From commercially available pectin, (OBIPEKTIN AG), Pectic Acid was isolated by alkaline catalysed hydrolysis and physicochemically characterized. The conductivities of aqueous solutions of tetramethyl-, tetraethyl-, tetra-n-propyl- and tetra-n-butyl pectate were determined. The concentration dependence of the conductivity as well as the conductometric titration of the investigated systems exhibited typical polyelectrolyte behaviour. The mobility of the polyelectrolyte solute was found to be influenced by the nature of the counterion. The calculated values of the molar conductivity deduced on the basis of the Manning limiting law were found to be lower than the experimental ones. The fraction of free counterions was evaluated and found to depend on the concentration and on the nature of the counterion.
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apparent molal volumes of Pectic Acid and some tetra n alkylammonium salts of Pectic Acid
European Polymer Journal, 1997Co-Authors: Helena Abramovic, Cveto KlofutarAbstract:Abstract From commercially available pectin (OBIPEKTIN AG), Pectic Acid was isolated by alkaline catalysed hydrolysis and physico-chemically characterised. The densities of aqueous solutions of tetramethyl-, tetraethyl-, tetra-n-propyl- and tetra-n-butylammonium pectate were determined at concentrations up to 0.016 g·cm −3 with a vibrating tube densimeter at 298 K. The concentration dependence of the derived apparent molal volumes and the influence of the nature of the counterion on the apparent molal volume was investigated. Thereby, a linear increase in the apparent molal volume, determined at the reference concentration, with increasing number of carbon atoms in the counterion was found. The experimental values of the apparent molal volumes approached a logarithmic dependence on concentration. The theoretical expression for the concentration dependence of the apparent molal volumes was interpreted on the basis of the cell-model of a polyelectrolyte solution and on the basis of infinite-line-charge theory. The experimental values of the apparent molal volumes were found to be higher than theoretical ones in the concentration range investigated.
Helena Abramovic - One of the best experts on this subject based on the ideXlab platform.
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viscosities and apparent specific volumes of Pectic Acid and its lithium salt in aqueous solutions
Food Hydrocolloids, 1998Co-Authors: Helena Abramovic, Cveto KlofutarAbstract:Abstract From commercially available apple pectin, Pectic Acid was isolated by alkaline catalysed hydrolysis and physico-chemically characterised. The densities and viscosities of aqueous solutions of Pectic Acid and its lithium salt were determined at concentrations up to 0.016 g cm −3 . The effect of the addition of simple salt and the degree of neutralisation on the apparent specific volume and on the limiting viscosity number of dilute aqueous solutions of Pectic Acid and its lithium salt was investigated
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conductivity of some tetra n alkylammonium salts of Pectic Acid
European Polymer Journal, 1997Co-Authors: Helena Abramovic, Cveto KlofutarAbstract:From commercially available pectin, (OBIPEKTIN AG), Pectic Acid was isolated by alkaline catalysed hydrolysis and physicochemically characterized. The conductivities of aqueous solutions of tetramethyl-, tetraethyl-, tetra-n-propyl- and tetra-n-butyl pectate were determined. The concentration dependence of the conductivity as well as the conductometric titration of the investigated systems exhibited typical polyelectrolyte behaviour. The mobility of the polyelectrolyte solute was found to be influenced by the nature of the counterion. The calculated values of the molar conductivity deduced on the basis of the Manning limiting law were found to be lower than the experimental ones. The fraction of free counterions was evaluated and found to depend on the concentration and on the nature of the counterion.
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apparent molal volumes of Pectic Acid and some tetra n alkylammonium salts of Pectic Acid
European Polymer Journal, 1997Co-Authors: Helena Abramovic, Cveto KlofutarAbstract:Abstract From commercially available pectin (OBIPEKTIN AG), Pectic Acid was isolated by alkaline catalysed hydrolysis and physico-chemically characterised. The densities of aqueous solutions of tetramethyl-, tetraethyl-, tetra-n-propyl- and tetra-n-butylammonium pectate were determined at concentrations up to 0.016 g·cm −3 with a vibrating tube densimeter at 298 K. The concentration dependence of the derived apparent molal volumes and the influence of the nature of the counterion on the apparent molal volume was investigated. Thereby, a linear increase in the apparent molal volume, determined at the reference concentration, with increasing number of carbon atoms in the counterion was found. The experimental values of the apparent molal volumes approached a logarithmic dependence on concentration. The theoretical expression for the concentration dependence of the apparent molal volumes was interpreted on the basis of the cell-model of a polyelectrolyte solution and on the basis of infinite-line-charge theory. The experimental values of the apparent molal volumes were found to be higher than theoretical ones in the concentration range investigated.
Wosiacki Gilvan - One of the best experts on this subject based on the ideXlab platform.
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Enzimas pectinoliticas de Fusarium oxysporum Schlecht. ex. Fr. isolado de frutos de cafe
[s.n.], 2018Co-Authors: Wosiacki GilvanAbstract:Orientador: Yong K. ParkTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos e AgricolaResumo: Microrganismos isolados de frutos de café cereja foram testados no que diz respeito a sua capAcidade pectinolítica e maceração de tecidos vegetais. Fusarium oxysporum Schlecht.ex Pr., crescido em meio constituído de farelo -úmido, demonstrou produzir enzimas extracelulares capazes de despolimerizar rapidamente polissacarídeos vegetais, como celulose, amido, xilano e arabano, além de substâncias Pecticas. 0 sistema pectinolítico foi fracionado por técnicas de troca iônica e filtração em gel, demonstrando ser constituído de três endopoligalacturonases, com atividade ótima em torno de pH 6,0. Não foram constatadas as atividades pectinesterase nem pectina transeliminase. As enzimas pectinolíticas purificadas demonstraram Km 0,12%, 0,022% e 0,019% e como produto de hidrolise foram constata dos oligossacarídeos ácidos em todos os casos. A hidrólise de ácido péctico foi inibida pela presença de cátions divalentes no meio de reação e agentes quelantes de metais foram eficientes em proporcionar melhores condições para a atividade enzimática. Tanto enzimas purificadas quanto a preparação bruta foram capazes de hidrolisar substâncias pécticas isoladas de limão e de frutos de caféAbstract: The pectinolytic and cell-dissolving ability of microorganisms isolated from coffee cherries was studied. The fungus Fusarium oxysporum Schlecht.ex Fr., when grown on moistened bran, developed enzymes capable of rapidly depolymerizing such vegetable polysaccharides as celulose starch, xylan and araban besides Pectic substances. This pectinolytic enzyme system was fractionated by ion exchange chromatography and gel filtration into three polygalacturonases with optimal activity at a pH around 6,0. No pectinesterase and pectintranseliminase activity were detected. Michaelis-Menten constants (Km) measured for the three enzymes were 0,12 , 0,022 e 0,019% while Acid oligosaccharides were the end products in all cases. Pectic Acid hydrolysis was inhibited by the presence of divalent cations in the reaction mixture while chelating agents were effective adjuvants, sometimes accelerating the reaction. The crude extract as well as the purified enzymes obtained from this fungus were effective in hydrolysis of Pectic substances isolated from lemon and coffee fruitsDoutoradoDoutor em Ciência de Alimento
M Demarty - One of the best experts on this subject based on the ideXlab platform.
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calcium and Acidic pectin distribution in flax cell walls evidence for different kinds of linkages in the cell junction and middle lamella of the cortical parenchyma of flax hypotocyl
Plant Physiology and Biochemistry, 1995Co-Authors: Christophe Rihouey, Alain Jauneau, A Cabinflaman, M Demarty, F Lefebvre, C MorvanAbstract:We used three different sample preparation methods (conventional glutaraldehyde-fixation, pyroantimonate precipitation method and a cryo-method) to investigate the distribution of calcium by secondary ion mass spectrometry in the cortical cell walls of flax seedling hypocotyl. The ionic images of calcium distribution were compared to the transmission electron microscopy images of the distribution of Pectic polysaccharides. For Pectic Acid localization both a direct labelling with gold-labelled endopolygalacturonase (endoPG, EC 3.2.1.15), and an indirect subtractive method using the same enzyme as a specific extracting agent were used. Our results show that, whatever the method used to prepare the samples, the calcium signal was lower in the cell walls of the cortical parenchyma than in the cell walls of the epidermal and subepidermal layers especially in the tricellular junctions. In the cortical cell walls, Acidic pectins were mainly located in the middle lamella, in the corner of the intercellular spaces and the wall area surrounding air-spaces. The removal of Pectic polysaccharides from these wall-microdomains observed when samples were treated with the endoPG was strongly inhibited in the presence of calcium ions. Thus, these cations were able to prevent the endoPG-induced disorganization of the cortical parenchyma of flax hypocotyl. This finding indicates that at this step of flax growth (a) the amount of calcium loaded in these wall areas was too low to promote the formation of calcium bridges and (b) the Pectic polysaccharides were linked to the cell wall through different kinds of linkages depending to the wall areas, and most importantly through covalent linkages.
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endopolygalacturonase gold complex parameters influencing the labelling of Pectic Acid in the cell walls of flax hypocotyl
Journal of Microscopy, 1993Co-Authors: A Cabinflaman, Alain Jauneau, Claudine Morvan, M DemartyAbstract:Summary An enzyme/colloidal-gold complex was prepared using a purified endopolygalacturonase (endoPGH, E.C. 3.2.1.15). Gold particles with a radius of 4·8 nm were prepared. To stabilize the gold particles, it was necessary to add a minimal amount of enzyme (approximately 0·5 μg) at a pH higher than its isoelectric pH. Under these conditions, the number of protein molecules adsorbed per gold particle was approximately one. The parameters influencing the diffusion of the endoPGH-gold complex to its target molecules were screened and tested through quantitative approaches: (i) the labelling efficiency q was calculated according to the equation for the diffusion of gold markers from the bulk solutions to target molecules and (ii) the labelling density N/S was measured by counting gold particles on electron micrographs. The highest value of N/S was obtained by determining the optimal values for the parameters outlined in the equation for q. To obtain the highest value of N/S, it was not necessary to choose values for these parameters which gave high values for q. The specificity of the probe towards homogalacturonic Acid blocks was established through controls. The localization of these blocks was illustrated throughout the walls of different kinds of flax seeding cells.
Gilvan Wosiacki - One of the best experts on this subject based on the ideXlab platform.
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Enzimas pectinoliticas de Fusarium oxysporum Schlecht. ex. Fr. isolado de frutos de cafe
2017Co-Authors: Gilvan WosiackiAbstract:Resumo: Microrganismos isolados de frutos de café cereja foram testados no que diz respeito a sua capAcidade pectinolítica e maceração de tecidos vegetais. Fusarium oxysporum Schlecht.ex Pr., crescido em meio constituído de farelo -úmido, demonstrou produzir enzimas extracelulares capazes de despolimerizar rapidamente polissacarídeos vegetais, como celulose, amido, xilano e arabano, além de substâncias Pecticas. 0 sistema pectinolítico foi fracionado por técnicas de troca iônica e filtração em gel, demonstrando ser constituído de três endopoligalacturonases, com atividade ótima em torno de pH 6,0. Não foram constatadas as atividades pectinesterase nem pectina transeliminase. As enzimas pectinolíticas purificadas demonstraram Km 0,12%, 0,022% e 0,019% e como produto de hidrolise foram constata dos oligossacarídeos ácidos em todos os casos. A hidrólise de ácido péctico foi inibida pela presença de cátions divalentes no meio de reação e agentes quelantes de metais foram eficientes em proporcionar melhores condições para a atividade enzimática. Tanto enzimas purificadas quanto a preparação bruta foram capazes de hidrolisar substâncias pécticas isoladas de limão e de frutos de caféAbstract:The pectinolytic and cell-dissolving ability of microorganisms isolated from coffee cherries was studied. The fungus Fusarium oxysporum Schlecht.ex Fr., when grown on moistened bran, developed enzymes capable of rapidly depolymerizing such vegetable polysaccharides as celulose starch, xylan and araban besides Pectic substances. This pectinolytic enzyme system was fractionated by ion exchange chromatography and gel filtration into three polygalacturonases with optimal activity at a pH around 6,0. No pectinesterase and pectintranseliminase activity were detected. Michaelis-Menten constants (Km) measured for the three enzymes were 0,12 , 0,022 e 0,019% while Acid oligosaccharides were the end products in all cases. Pectic Acid hydrolysis was inhibited by the presence of divalent cations in the reaction mixture while chelating agents were effective adjuvants, sometimes accelerating the reaction. The crude extract as well as the purified enzymes obtained from this fungus were effective in hydrolysis of Pectic substances isolated from lemon and coffee fruit