Viscosity Of Pectin Solutions Research Articles

Effect of combination of pectin substances on viscosity of their aqueous solutions

Viscosity is one of the characteristic properties of pectin substances, as well as other lyophilic colloids. Pectin molecules are easily associated with each other or with large molecules of related substances. This article contains the results of the study of dynamic viscosity, internal friction, thixotropic index of aqueous solutions (1 % and 4%) of various types of pectin substances and their combinations. The article presents the results of the study of the influence of different types of pectin substances and their combinations on the dynamic viscosity of pectin solutions and their internal friction. The analysis of values of dynamic viscosity and friction force depending on the type of pectin substances and their combinations is given. It is established that in cases where information on dissipative processes in pectin structures at low speeds and shear loads is required, it is necessary to rely on data on internal friction, in others - on the given information on their viscosity. The thixotropic index is calculated. It is established that the internal friction in pectin solutions and their dynamic viscosity depend on the type of pectin substances and their combinations. In pectin solutions, the internal friction is maximum for Apple pectin, and the dynamic viscosity – for a combination of citrus pectins with beet. When combining pectins, both indicators are most important for the combination of citrus with beet. The obtained data on the viscosity, internal friction and thixotropic index of solutions of different types and combinations of pectins make it possible to regulate the rheological properties of food systems with the addition of pectin substances.

The Effect of Concentration on the Cross-Linking and Gelling of Sodium Carbonate-Soluble Apple Pectins.

The cross-linking and gelation of low-methoxy pectins are basic processes commonly used in different industries. The aim of this research was to evaluate the cross-linking process of the sodium carbonate-soluble pectins (named DASP) extracted from apples, characterized by a low degree of methylesterification as a function of its concentration in water (CDASP). The cross-linking process was studied with a dynamic light scattering method, atomic force microscope (AFM), viscosity and pH measurements. An increase in CDASP above 0.01% resulted in a decrease in the aggregation index (AI) and the change of its sign from positive to negative. The value of AI = 0 occurred at CDASP = 0.33 ± 0.04% and indicated the formation of a pectin network. An increase in CDASP caused the changes in viscosity of pectin solutions and the nanostructure of pectins spin-coated on mica observed with AFM, which confirmed results obtained. The hydrogen bonds were involved in the cross-linking process.

PARÁMETROS REOLÓGICOS DE SOLUCIONES DE GOMA XANTANA/PECTINAEN FUNCI ́ON DE LA TEMPERATURA Y COMPOSICIÓN

The rheological behavior of individual solutions and blends of xanthan gum (0.1 to 0.5 %) and pectin (1.6 to 2.0 %) was studied at 25, 50 and 75 °C using a D-optimal mixture experimental design. Pectin and xanthan gum solutions were found to be Newtonian and non-Newtonian fluids, respectively. The effect of the temperature on the viscosity of pectin solutions and the consistency index (K) of xanthan gum were modeled by the Arrhenius equation. The xanthan gum/pectin mixtures predominantly behaved as pseudoplastic fluids and were described by the power law model. Mathematical models were developed to predict the flow behavior index and the consistency index as a function of the blends composition, at the studied temperature. The activation energy of flow was expressed in terms of the concentrations of the components of the mixtures. The obtained mathematical models are useful for predicting the rheological parameters of pectin and xanthan gums blends and for evaluating possible applications.

Cloning, expression of Aspergillus niger JL-15 endo-polygalacturonase A gene in Pichia pastoris and oligo-galacturonates production

The endo-galacturonase A gene (pgaA) was cloned using the cDNAs synthesized from total RNA of Aspergillus niger JL-15 by reverse transcription as template. The open reading frame (ORF) of pgaA was 1113bp, encoding a peptide of 370 amino acids with the predicted molecular mass of 38.8kDa. The pgaA was successfully expressed in Pichia pastoris GS115 under the control of AOX1 promoter. After induction by methanol for 96h, the activity of the recombinant endo-galacturonase A (rePgaA) in culture supernatant was 2091.0U/mg. SDS–PAGE analysis showed that the molecular mass of rePgaA was about 40.0kDa. Enzymatic properties assays showed that the optimum temperature and pH for rePgaA were 50°C and pH 5.0, respectively. The Michaelis–Menten constant (Km) and maximal velocity (Vmax) of rePgaA for citrus pectin were 3.20mgml−1 and 40.97μmolmin−1ml−1, respectively. The rePgaA mediated a rapid decrease in viscosity of pectin solution with release of small amount of reducing sugar. High performance liquid chromatography (HPLC) analysis revealed that digalacturonate (G2) and trigalalcturonate (G3) were the main hydrolysis products released from pectin by rePgaA. The rePgaA showed very low activity on G2 and G3, which suggested it was a typical endo-acting enzyme.

Characterization of orange peel pectin and effect of sugars, l-ascorbic acid, ammonium persulfate, salts on viscosity of orange peel pectin solutions

Anhydrogalacturonic acid, methoxyl, acetyl, ash contents and optical rotation of pectin obtained by a HCl extraction procedure (90°C, pH=2.5, 90 min) were found to be 74.30, 12.15, 0.37, 6.07% (DM basis) and +252° respectively. The degree of methylation was found to be over 50%, indicating that the orange peel pectin had a high methoxyl content. The reduced viscosities of orange peel pectin obtained by the HCl extraction procedure were measured in aqueous solutions and in the presence of dextrose, maltose and dextrin. Dextrose and maltose were found to increase the reduced viscosity of pectin solutions whereas dextrin decreased it. The viscosity-enhancing effect of dextrose and maltose can be interpreted in terms of the decrease in dielectric constant of the solvent, dehydration action, and hydrogen bonding formation. The specific fluidity of pectin solutions has been observed to be directly proportional to time through the depolymerization effect of l-ascorbic acid. When the concentrations of the pectin solutions were increased in the presence of ammonium persulfate, the increase in the ratio of reduced viscosity to initial reduced viscosity was higher. In addition, the effect of some salts on the viscosity of the pectin solution was examined. The viscosity of the pectin solutions decreased in the presence of salts. When the salt concentration increased, great decreases were observed in the low salt concentrations.

The use of commercial pectinase in fruit juice industry. Part I: viscosimetric determination of enzyme activity

The kinetics of commercial pectinase, Pectinex Ultra SP-L, in a batch reactor was studied. The change in viscosity of pectin solution was followed by an enzymatic assay to determine pectolytic activity of the enzyme preparation. The pectolytic activity of Pectinex Ultra SP-L was measured at pH 3.5 and 35°C and found to be 0.025 pectin % (w/v)/sec/enzyme % (v/v). The Michaelis-Menten constant (Km) of enzyme preparation was found to be 1.137 pectin % (w/v). The temperature dependence of the reaction rate was obeying the Arrhenius Law. The activation energy of the biochemical reaction catalysed by commercial pectinase was calculated as 9.316 kcal mol−1.

Filtration of sugar-beet pulp pectin extract and flow properties of pectin solutions

Sugar-beet pulp pectin extract was vacuum filtered at 25 °C and different filtration pressures (0.20 × 10 5, 0.33 × 10 5 and 0.47 × 10 5 Pa). The measurement of the average specific cake resistance was discussed. The specific cake resistance was dependent on the filtration pressure. The cake compressibility coefficient at 25 °C was calculated as 0.389. The correlation between the pressure drop and the average specific cake resistance showed that sugar-beet pectin forms a compressible filter cake. By using kieselguhr as a filter aid to increase the filtration efficiency, the effects of varying the precoating amount and the filter aid dose on the average specific cake resistance of cake at a constant pressure filtration were studied. The effects of temperature and concentration on the viscosity of pectin solutions were examined at six different temperatures between 20 and 70 °C and four concentration levels between 0.005 and 0.020 kg l −1. The activation energy for viscous flow was in the range 6.69–13.46 kJ mol −1. Equations describing the combined effects of temperature and concentration on the viscosity are given.

Immobilization of pectin lyase from Penicillium italicum by covalent binding to nylon

Pectin lyase [PNL, poly(methoxygalacturonide) lyase; E.C. 4.2.2.10] from Penicillium italicum was immobilized by covalent binding to Nylon 6 in order to compare physico-chemical and kinetic properties of the soluble and immobilized counterpart. Optimum conditions for the immobilization process, kinetic parameters, and pH and temperature behavior of the enzyme were determined. The pH activity curve of the immobilized enzyme shifted toward a low pH compared with that of the soluble one. Similarly, the immobilized PNL was more stable at lower pHs than the soluble enzyme. The immobilization caused a marked increase in the thermal stability of the enzyme. The immobilized PNL was extraordinarily stable during storage at 4°C. No loss of activity was observed when the immobilized enzyme was used for 12 consecutive cycles of operation. In comparison with the soluble enzyme, the immobilized PNL caused a lower decrease in the viscosity of pectin solutions. Nevertheless, when fruit juices were used, the drop in initial viscosity was as marked as that observed when the soluble enzyme was used to clarify pectin solutions. Nylon-immobilized PNL appears promising for the clarification of fruit juices at 40°C and approximate pH of 3.0.

Filtration of pectin extract from grapefruit peel and viscosity of pectin solutions

The yield of pectin extracted (85 °C, pH = 2.5, 90 min) by acidified water in a ratio of 25 parts per part of dry peel from dried grapefruit peel was 21.1% (DM basis). The pectin extract was vacuum filtered at different temperatures and under various pressure differences, and the average specific cake resistances were determined. The specific cake resistance was highly dependent on the filtration pressure. The cake compressibility coefficients at 15 °C, 25 °C and 35 °C were calculated as 0.387, 0.379 and 0.379, respectively. The filtration rate observed at 15 °C was higher than that at 25 °C due to flocculation at low temperature. The effects of temperature and concentration on the viscosity of pectin solutions were examined at six different temperatures between 10 °C and 60 °C and four concentration levels between 0.3 g/100 ml and 1.4 g/100 ml. The activation energy for viscous flow was in the range 2·10–3·77 kcal mol −1. Finally, the combined effect of temperature and concentration on the viscosity was expressed as η = 8.52 × 10 −5 exp( −1.6162 C + 1.807 exp(0.5493 C) RT )

The effect of nitric acid extraction variables on orange pectin

Pectin was extracted from dry orange waste with nitric acid. A factorial experimental design was used and the effects of temperature, time and pH of extraction on pectin yield and ‘jelly units’, ie pectin yield × viscosity of pectin solution were determined. Optimum conditions for pectin extraction are also discussed. According to ash and methoxyl content determinations the product can be classified as low ash and high methoxyl pectin. Its purity expressed as anhydrogalacturonic acid content varied from 68.5 to 75.0%.

Optimization of pectin extraction from dried peel of citrus grandis

The influence of acid concentration, temperature, and extraction time on pectin extracted from dried peel of Citrus grandis have been investigated. The dependence of pectin yield and of the relative viscosity of pectin solution on experimental conditions has been described by mathematical models.

The effect of sugars on viscosity of pectin solutions. I. Comparison of corn sirup with sucrose solutions.

Abstract The relative viscosity of citrus pectin solutions in the range of 0 to 0.20% in 23.5% sucrose, in 23.5% corn sirup solids, and in mixtures of these was measured to investigate the interaction between pectin and sugar or corn sirup saccharides. Sucrose was found to increase the viscosity of pectin solutions whereas corn sirup solids reduced it. The interaction was found to involve conformational changes in the pectin micelle of the type reported by Liberti and Stivala for a number of polyelectrolytes. The results obtained conform better to the Liberti and Stivala interpretation of interaction than to the Fuoss interpretation. The difference between sucrose and corn sirup solids was ascribed to the possible effect of dextrins present rather than to the effect of dextrose or maltose.

Electrolytes and the Viscosity of Pectin Solutions

Electrolytes and the Viscosity of Pectin Solutions

Citrates and the Viscosity of Pectin Solutions

Citrates and the Viscosity of Pectin Solutions