Electric double layer and electrokinetic potential of pectic macromolecules in sugar beet

Electrokinetic potential is an important property of colloidal particles and, regarding the fact that it is a well defined and easily measurable property, it is considered to be a permanent characteristic of a particular colloidal system. In fact, it is a measure of electrokinetic charge that surrounds the colloidal particle in a solution and is in direct proportion with the mobility of particles in an electric field. Gouy-Chapman-Stern-Graham's model of electric double layer was adopted and it was proven experimentally that the addition of Cu++ ions to sugar beet pectin caused a reduction in the negative electrokinetic potential proportional to the increase of Cu++ concentration. Higher Cu++ concentrations increased the proportion of cation specific adsorption (Cu++ and H+) with regard to electrostatic Coulombic forces. Consequently, there is a shift in the shear plane between the fixed and diffuse layers directed towards the diffuse layer, i.e. towards its compression and decrease in the electrokinetic potential or even charge inversion of pectin macromolecules

Mass transfer and microbiological profile of pork meat dehydrated in two different osmotic solutions

The effects of osmotic dehydration on mass transfer properties and microbiological profile were investigated in order to determine the usefulness of this technique as pre-treatment for further treatment of meat. Process was studied in two solutions (sugar beet molasses, and aqueous solution of sodium chloride and sucrose), at two temperatures (4 and 22°C) at atmospheric pressure. The most significant parameters of mass transfer were determined after 300 minutes of the dehydration. The water activity (aw) values of the processed meat were determined, as well as the change of the microbiological profile between the fresh and dehydrated meat. At the temperature of 22°C the sugar beet molasses proved to be most suitable as an osmotic solution, despite the greater viscosity

Chromatographic behavior and lipophilicity of s-triazine derivatives on silica gel impregnated with paraffin oil

The chromatographic behavior of four group of s-triazine derivatives (14 compounds) has been studied by TLC on silica gel impregnated with paraffin oil. Retention mechanism has been determined using the following mobile phases: water-acetone, water-acetonitrile, water-dioxane, water-tetrahydrofuran, water-methanol and water-ethanol, by changing the volume fraction of modifier in the mobile phase. On impregnated silica gel, a reversed-phase chromatographic process occurs. Good correlation was obtained between the retention constants, RM 0 (determined by linear extrapolation), and slope, S, of chromatographic equations. There was also satisfactory correlation between these retention constants and logP values calculated using different theoretical methods. The study showed that the retention constants can be used as a measure of lipophilicity of investigated compounds

Chromatographic behavior and lipophilicity of s-triazine derivatives on silica gel impregnated with paraffin oil

The chromatographic behavior of four group of s-triazine derivatives (14 compounds) has been studied by TLC on silica gel impregnated with paraffin oil. Retention mechanism has been determined using the following mobile phases: water-acetone, water-acetonitrile, water-dioxane, water-tetrahydrofuran, water-methanol and water-ethanol, by changing the volume fraction of modifier in the mobile phase. On impregnated silica gel, a reversed-phase chromatographic process occurs. Good correlation was obtained between the retention constants, RMθ (determined by linear extrapolation), and slope, S, of chromatographic equations. There was also satisfactory correlation between these retention constants and logP values calculated using different theoretical methods. The study showed that the retention constants can be used as a measure of lipophilicity of investigated compounds

Osmotic dehydration of carrot in sugar beet molasses: Mass transfer kinetics

The osmotic dehydration process of carrot in sugar beet molasses solutions (40, 60 and 80%), at three temperatures (45, 55 and 65°C) and atmospheric pressure, was studied. The main aim was to investigate the effects of immersion time, working temperature and molasses concentration on mass transfer kinetics during osmotic dehydration. The most important kinetic parameters were determined after 20, 40, 60, 90, 120, 180, 240 and 300 min of dehydration. Diffusion of water and solute was the most intensive during the first hour of the process and the maximal effect was observed during the first 3 hours of immersion. During the next two hours of dehydration, the process stagnated, which implied that the dehydration time can be limited to 3 hours

Osmotic dehydration of red cabbage in sugar beet molasses: Mass transfer kinetics

The paper describes a study of osmotic dehydration of red cabbage in sugar beet molasses of different concentrations (40, 60 and 80%) at 50°C and under atmospheric pressure. The best results were obtained at the sugar beet molasses of 80% as an osmotic medium. The most important kinetic parameters of the process were determined: water loss, solid uptake, weight reduction, normalized solid content and normalized moisture content. The kinetic parameters were determined after 1, 3 and 5 hours. Mass transfer coefficients were calculated using Hawkes and Flink's model and the results indicate that the diffusion of water and solids was the most intensive during the first three hours of dehydration

Accumulation of Potentially Toxic Elements in Invasive Ambrosia artemisiifolia on Sites with Different Levels of Anthropogenic Pollution

This study investigated invasive Ambrosia artemisiifolia from five localities with different levels of anthropogenic pollution in order to determine the potential for accumulation of trace metals and metaloids. Physical characteristics of the soil are presented, together with concentrations of As, B, Ba, Ca, Cd, Co, Cu, Fe, Mg, Mn, Mo, Ni, Pb, Sb, Sr, and Zn in both plant and soil. The tested samples displayed considerable differences in element concentrations, depending on the level of anthropogenic activities, with the highest concentrations of elements observed in samples from Stolice and Piskanja, the sites with most intensive human influence. A trend of shoot accumulation can be observed in A. artemisiifolia, but without hyperaccumulation, along with lower root concentrations in almost all analyzed samples. This may pose an additional environmental risk, as accumulated elements can spread to other components of the ecosystem. While A. artemisiifolia acumulates a high and even toxic rate of B in shoots regardless of boron concentration in soil, there is a high correlation of Ba, Pb, and Zn concentrations in species shoots with their respective concentration in the soil. Successful colonization of both natural and anthropogenically polluted habitats indicates high tolerance of A. artemisiifolia, which complements its wide environmental amplitude

Estimation of the correlation between the retention of s-triazine derivatives and some molecular descriptors

In this study, 14 newly synthesized s-triazine derivatives were investigated by means of reversed-phase thin-layer chromatography (TLC) on C-18 stationary and two different mobile phases: acetonitrile-water and methanol-water. Quantitative structure-retention relationship (QSRR) was developed for a series of s-triazine compounds by the multiple linear regression (MLR) analysis. An MLR procedure was used to model the relation-ships between molecular descriptors and retention of s-triazine derivatives. Physico-chemical molecular descriptors were calculated from the optimized structures. Statistically significant and physically meaningful QSRRs were obtained

Application of lipophilicity parameters in QSRR analysis of newly synthesized s-triazine derivatives: Prediction of the retention behavior

Considerable attention has been paid to the analysis of chemicals in the s-triazine group, due to their widespread use in agricultural chemistry and their subsequent impact on biological systems. For initial chemical screening of the activity of newly synthesized compounds, it is recommended to determine their lipophilicity and physico-chemical property in relation to biological activity. Lipophilicity is difficult to quantify. The most widely accepted measure of lipophilicity is the octanol-water partition coefficient. Measurement of the octanol-water partition coefficients is achieved by an alternative method, i.e. reversed-phase liquid chromatography. Reversed-phase thin-layer chromatography (RP TLC) is a rapid method for the analysis of large number of s-triazine type compounds. Certain relationship between the structure of s-triazine compounds and their mobility on silica gel impregnated with paraffin oil have recently been demonstrated. The retention behavior of compounds in various chromatographic systems strongly depends on their physico-chemical properties. Recently, much effort was given in finding adequate mathematical model relating the retention of the given analyte to its physico-chemical and structural parameters (descriptors). These correlations are known as quantitative structure-retention relationships (QSRR), which offer a powerful tool for the prediction of separation behavior. The QSRR equations describing retention constants RM0, determined for different modifiers in mobile phase in terms of logarithms of n-octanol-water partition coefficients, were derived. The partition coefficients (AlogPs, AClogP, AB/logP, milogP, AlogP, MlogP, logPKowin, XlogP2, XlogP3, ACDlogP i ClogP) were calculated by application of different software packages. The goal of this paper was to select the logP data and TLC system that best characterize octanol/water partitioning and thus the lipophilicity of the investigated molecules

Application of Peleg model to study mass transfer during osmotic dehydration of apple in sugar beet molasses

The applicability of Peleg equation was examined for the description of mass transfer during osmotic dehydration (OD) of apple in sugar beet molasses. Mass transfer was investigated in terms of water loss (WL) and solid gain (SG), during OD in 40-80% sugar beet molasses solutions, at 45, 55 and 65ºC. High regression coefficients obtained for Peleg constants (R2>0.975) indicate good fit to the experimental data. The Peleg rate constant varied from 0.144 to 0.785 (g/g i.s.w.) and from 2.006 to 4.436 (g/g i.s.w.) for WL and SG, respectively. The Peleg capacity constant varied from 1.142 to 1.553 (h g/g i.s.w.) and from 8.254 to 11.930 (h g/g i.s.w.) for WL and SG, respectively. The equilibrium WL∞ and SG∞ were estimated using the Peleg model. In addition, the activation energy (Ea) for WL and SG was determined from the relationship between the Peleg rate constant and Arrhenius equation