Effects Of Salt Type Research Articles

Alaska Pollock Fish Protein Gels as Affected by Refined Carrageenan and Various Salts

AbstractRefined iota and kappa carrageenans were added (0, 0.25, 0.5, 0.75 and 1.0%) to Alaska pollock surimi and combined with various salts (NaCl, KCl or CaCl2, respectively) at 2%. Sample pastes were subjected to dynamic rheology (temperature sweep heating 20–80C and cooling 80–20C). Gel properties (breaking force, penetration distance and water retention ability [WRA]) were measured at 0, 3, 6 and 9 freeze/thaw cycles. The effect of salt type indicated that NaCl significantly (P < 0.05) increased force values, whereas KCl increased (P < 0.05) penetration distance. WRA was improved (P < 0.05) by KCl, followed by NaCl and CaCl2, respectively. Kappa carrageenan increased (P < 0.05) force values. However, adding kappa and iota carrageenans tended to decrease penetration distance. Iota carrageenan (0.25–1.0%) generally increased (P < 0.05) or did not significantly (P > 0.05) affect WRA compared to kappa carrageenan. Utilizing KCl and NaCl combined with kappa and iota carrageenans could increase gel strength and WRA.Practical ApplicationsIota carrageenan tended to improve or maintain water retention ability of Alaska pollock fish protein gels during extended freeze/thaw cycles compared to when kappa carrageenan was added. However, kappa carrageenan tended to improve force values or gel strength of Alaska pollock fish protein gels. Therefore, a mixture of kappa and iota carrageenans should be evaluated to maximize the respective properties and optimize the amount of each carrageenan type in order to improve functionality of Alaska pollock fish protein gels. In addition, further study to utilize a combination of NaCl and KCl rather than a single salt type could further maximize the functionality of an iota–kappa carrageenan blend in Alaska pollock fish protein gels.

The effects of raw materials particle size and salt type on formation of nano-CaZrO3 from molten salts

Nano-CaZrO3 was successfully synthesized at 800°C using the molten-salt method, and the effects of salt type and raw materials particle size on the formation of CaZrO3 were investigated. Na2CO3, CaCl2, nano-ZrO2 and micro-ZrO2 were used as starting materials. On heating, Na2CO3 reacted with CaCl2 to form NaCl and in situ CaCO3. Na2CO3–NaCl molten eutectic salt provided a liquid medium for reaction of CaCO3 and ZrO2 to form CaZrO3. The results demonstrated that in both nano- and micro-ZrO2 inclusive samples, CaZrO3 started to form at about 700°C and that, after the temperature was increased to 1000°C, the amounts of CaZrO3 in the resultant powders increased with a concomitant decrease in CaCO3 and ZrO2 contents. After washing with hot-distilled water, the samples containing nano- and micro-ZrO2 heated for 3h at 800°C and 1000°C, were single-phase CaZrO3 with 70–90nm and 400–450nm particle size, respectively. Also, the synthesis process was completed in lower temperatures using eutectic salts. Furthermore, the synthesized CaZrO3 particles retained the size and morphology of the ZrO2 powders, which indicated that a template formation mechanism dominated the formation of CaZrO3 by molten-salt synthesis.

Dilute solution properties of wild sage (Salvia macrosiphon) seed gum

In this paper, the effect of salt type (sodium and calcium chlorides), salt concentration (0, 0.5, 20 and 50mM) and temperature (20, 30 and 40°C) on the properties of dilute sage seed gum (SSG) solutions were investigated. SSG was evaluated for intrinsic viscosity by various models i.e. Huggins, Kraemer, Higiro and Tanglertpaibul and Rao equations. The results showed that the Tanglertpaibul & Rao and Higiro equations were chosen as the best models for intrinsic viscosity determination of SSG at different temperatures and salts concentrations, respectively. The increase in ionic strength of the NaCl and CaCl2 from 0 to 0.5mM caused increase in intrinsic viscosity, but increasing the temperature from 20 to 40°C and salts concentrations from 0.5 to 50mM decreased the intrinsic viscosity. Divalent ions from CaCl2 showed a more pronounced effect on the intrinsic viscosity compared with monovalent ions from NaCl. SSG solutions at all temperatures and salts concentrations were in the dilute domain. The weight-average molecular weight of sage seed gum was obtained as 1.5×106Da.

Effect of Aqueous Two-Phase System Constituents in Different Poly(ethylene glycol)–Salt Phase Diagrams

Eight different poly(ethylene glycol) (PEG)/salt aqueous two-phase systems (ATPS's) were characterized at 23 °C. PEGs with different molecular weights (1500 and 8000) were combined with different salts (sodium or potassium citrates and formates) to study the effect of each ATPS constituent in the phase diagram. The binodal curve and several tie-lines were determined for each system using common analytical techniques described in the literature for ATPS's (cloud point method, conductivity, and gravimetric analysis after lyophilization). According to the results, it was found that each ATPS constituent produced a particular effect in the phase diagram. For the salts, changes in the anion produced larger variations in the heterogeneous region size than changes of the cation. Thus, the effect of salt type seems to be largely dependent on the anion, which makes the dominant contribution. The ability to form ATPS's is connected with the Gibbs energy of hydration, ΔGhyd, of the anions: more negative ΔGhyd values facilitate ATPS formation. Changes in the PEG molecular weight affected also the phase diagram: the size of the heterogeneous region increases with the increase in the polymer molecular weight.

Partition of Pepsinogen from the Stomach of Red Perch (Sebastes marinus) by Aqueous Two Phase Systems: Effects of the Salt Type and Concentration

An important acidic protease, pepsin is synthesized and secreted in the gastric membrane in an inactive state called pepsinogen (PG) and has applications in the food and manufacturing industries, collagen extraction, gelatin extraction and in regulating digestibility. Fish processing waste can be used to produce commercially valuable byproducts such as pepsinogen. In the present study, the purification of pepsinogen from the stomach of red perch using aqueous two phase systems (ATPS) formed by polyethylene glycol (PEG) and salt at 4°C was optimized. The effects of salt type (MgSO4, (NH4)2SO4, Na3C6H5O7 and K2HPO4) and concentration (6, 7, 8, 9, 10, 11, 12, 13, 15, 17, 19%) on the partitioning of PG were studied and parameters including total volume (TV), volume ratio (VR), enzyme activity (AE), protein content (Cp), specific activity (SA), partition coefficient (Kp), purification fold (PF) and recovery yield (RY) were evaluated. Salt type and salt concentration had significant effects on each parameter. MgSO4, (NH4)2SO4, Na3C6H5O7 and K2HPO4 required different critical salt concentrations (9, 12, 12 and 10%, respectively) to form biphasic systems. TV and VR decreased with increased salt concentration since salt formed hydrogen bonds with water molecules and created a more compact and ordered water structure. AE, CP, SA, PF and RY showed a maximum increase with intermediate salt concentration, while KP had the opposite pattern. The highest TV and AE values were obtained at 12% (NH4)2SO4 while the highest SA and PF values were obtained at 12% MgSO4. The highest TV and Cp values were obtained at 12 and 15% Na3C6H5O7, respectively. (NH4)2SO4 at 15% concentration gave the highest RY (71.7%) and was selected as the optimum salt type and concentration. Thus, 15% (NH4)2SO4 18% PEG 1500 was the optimal ATPS combination and presented the best partition. The values of SA and PF and RY obtained with ATPS method were two fold higher than those obtained with the ammonium sulphate fractionation (ASF) method.

Phase equilibria for salt-induced lysozyme precipitation: Effect of salt type and temperature

The salt-induced precipitation of lysozyme from aqueous solutions was studied through precipitation assays in which the equilibrium compositions of the coexisting phases were determined. Lysozyme precipitation experiments were carried out at 5, 15 and 25 °C and pH 7.0 with ammonium sulfate, sodium sulfate and sodium chloride as precipitating agents. In these experiments a complete separation of the coexisting phases (liquid and solid) could not be achieved. Nevertheless it was possible to determine the composition of the precipitate. The enzymatic activity of lysozyme in the supernatant phase as well as in the precipitate phase was also determined. The activity balance suggests that there is a relationship between the composition of the true precipitate and the total activity recovery.

Investigation of protein retention in hydrophobic interaction chromatographic (HIC) systems using the preferential interaction theory and quantitative structure property relationship models

The retention of proteins in hydrophobic interaction chromatographic (HIC) systems was investigated using the preferential interaction theory in concert with quantitative structure property relationship (QSPR) modeling. The numbers of water molecules and salt ions released upon protein binding were determined from ln ( k′) vs. salt concentration plots for a large number of proteins with a range of properties. The effect of salt type on protein binding was also studied by comparing the number of water molecules released in the presence of different salts. Quantitative structure property relationship (QSPR) models based on a support vector machine (SVM) approach were successfully generated for predicting the water molecules released values. These models employed protein crystal structure and primary sequence information as well as a set of hydrophobicity descriptors based on the solvent accessible surface area of the proteins. In addition to successfully predicting the water release values, the selected descriptors provide insights into the protein physicochemical properties which influence protein affinity in HIC system.

Effects of Salts and Preheating Temperature of Brine on the Texture of Pickled Cucumbers

ABSTRACTThe effects of salt type and preheating temperature on the texture and quality of pickled cucumber were studied. Four types of salt were used: bay salt, purified salt, and 2 prepared salts, 1 containing the same amount of Ca2+ and Mg2+ as those of bay salt, and the other containing a 3‐fold higher concentration of Ca2+ and Mg2+ than bay salt. Two different temperatures were used for the salt solutions: 98 °C and 65 °C. All samples were fermented for 30 d at 25 °C. To evaluate the quality of the pickled cucumber with fermentation, the pH level, total acidity, alcohol insoluble solids, and mineral contents were analyzed. Texture and sensory evaluation as well as a microscopic observation were performed to observe the textural change of the pickled cucumber during fermentation. Pickled cucumbers with 98 °C of preheated brine showed better texture than the ones with 65 °C. The pickled cucumbers brined with prepared salt, 1 which had the same amount of Ca2+ and Mg2+ to bay salt, displayed the best result among the samples tested, in terms of sensory, textural, and physical properties.

Effect of Salt Type on Hygroscopicity of a New Cephalosporin S-3578

Effect of salt type on hygroscopicity was evaluated using S-3578 salts. The hydration behavior of a sulfate and a nitrate salt of S-3578 were evaluated by powder X-ray diffraction (PXRD), simultaneous measurement of PXRD-differential scanning calorimetry (DSC), moisture sorption analysis, simultaneous measurement of thermogravimetric/differential thermal analyses, and solid state 13C-nuclear magnetic resonance (C-NMR). The sulfate salt incorporated two types of lattice water to form a monohydrate or a trihydrate. Additional water could also be absorbed as channel water to expand the lattice structure. The activation energy for dehydration was very high, probably due to steric hindrance in the lattice structure. The nitrate salt incorporated only one water molecule per compound as the lattice water. The additional water was absorbed as channel water as observed for the sulfate salt. X-ray diffractograms showed little dependence on the salt type under the ambient condition. The hydration number was likely to be affected by the size of the counter acids. The hygroscopicity of S-3578 salts was significantly altered by the salt type. The difference in the amount of the lattice water could be explained in terms of the difference in the molecular size of the counter acids.

Viscometric behavior of high-methoxy and low-methoxy pectin solutions

The hydrodynamic behavior of high-methoxy (HM) and low-methoxy (LM) pectin solutions was examined by capillary viscometric analysis. The LM-pectin was produced from the HM-pectin by PME-deesterification. As a result of the viscometric analysis, the PME-deesterified LM-pectin showed quite different solution behavior from the HM-pectin. The LM-pectin had larger intrinsic viscosity ([ η]) than HM-pectin when dissolved in 0.005 and 0.05 M concentrations of monovalent salts whereas HM-pectin had a higher value of [ η] when dissolved in 0.2 M salt than LM-pectin. The concentration dependence of HM-pectin η red values was fairly constant, whereas the concentration dependence of LM-pectin η red values had a tendency to decrease as the pectin concentration approached zero. The effect of salt-type on the hydrodynamic behavior of both HM- and LM-pectin solutions was almost negligible. The precipitous drop in LM-pectin [ η] upon increasing the salt concentration from 0.05 to 0.2 M is interpreted as arising from its disaggregation. This interpretation is based in part on data from HPSEC with online light scattering and viscosity detection.

An Analysis of the Interactions of BSA with an Anion-Exchange Surface Under Linear and Non-Linear Conditions

The interactions of BSA with an anion-exchange adsorbent have been studied to aid in the understanding of protein adsorption in ion-exchange chromatography. Linear chromatography, flow microcalorimetry and isotherm measurements were used to analyze adsorption energetics in the linear and overloaded regions of the equilibrium isotherm. The effects of salt type, salt and protein concentration, and temperature are reported. It was observed that under all conditions studied the adsorption process was entropically driven. This was contrary to expectations, since at the pH selected ion exchange is expected to dominate. A major driving force for the adsorption of BSA on the anion exchanger was concluded to be the increase in entropy from the release of water due to interactions between hydrophobic regions on the protein and adsorbent. The data further suggest that the conformational entropy change accompanying protein adsorption on the ion exchanger may also be significant.

Effect of salt type on mass transfer in reverse osmosis thin film composite membranes

Reverse osmosis separation of inorganic salts in aqueous solutions has been studied using polyamide thin film composite membrane, in spiral wound configuration. Various inorganic salts involving monovalent and divalent ions have been studied. The solute transport through the membrane and the mass transfer coefficient at the high pressure feed side of the spiral wound module were determined for each type of salt. The mass transfer coefficient of each inorganic salt was predicted from the experimental data for the reverse osmosis separation of sodium chloride as reference and the mass transfer empirical correlations. The values obtained were compared with the experimental ones. The free energy parameters for monovalent cations, monovalent anions and divalent cations have been calculated. These parameters were used to predict the reverse osmosis performance of inorganic salts in spiral wound reverse osmosis module. It was observed that the free energy values of the cations are negative while those of the anions are positive, suggesting that the surface of the membrane used is positively charged.

Modeling of the salt effects on hydrophobic adsorption equilibrium of protein

A two-state protein model is proposed to describe the salt effects on protein adsorption equilibrium on hydrophobic media. This model assumes that protein molecules exist in two equilibrium states in a salt solution, that is, hydrated and dehydrated states, and only the dehydrated-state protein can bind to hydrophobic ligands. In terms of the two-state protein hypothesis and the steric mass-action theory, protein adsorption equilibrium on hydrophobic media is formulated by a five-parameter equation. The model is demonstrated with the adsorption of bovine serum albumin to Phenyl Sepharose gels as a model system. The effects of salt type (sodium chloride, sodium sulfate and ammonium sulfate) on the model parameters are discussed. Then, the model formulism is simplified in terms of the small magnitude of the protein dehydration equilibrium constant in the model. This simplification has returned the model derived on the basis of the two-state protein hypothesis to its original mechanism of salt effects on the hydrophobic adsorption of protein. This simplified model also creates satisfactory prediction of protein adsorption isotherms.

Cloud-point temperatures for lysozyme in electrolyte solutions: effect of salt type, salt concentration and pH

Liquid–liquid phase-separation data were obtained for aqueous saline solutions of hen egg-white lysozyme at a fixed protein concentration (87 g/l). The cloud-point temperature (CPT) was measured as a function of salt type and salt concentration to 3 M, at pH 4.0 and 7.0. Salts used included those from mono and divalent cations and anions. For the monovalent cations studied, as salt concentration increases, the CPT increases. For divalent cations, as salt concentration rises, a maximum in the CPT is observed and attributed to ion binding to the protein surface and subsequent water structuring. Trends for sulfate salts were dramatically different from those for other salts because sulfate ion is strongly hydrated and excluded from the lysozyme surface. For anions at fixed salt concentration, the CPT decreases with rising anion kosmotropic character. Comparison of CPTs for pH 4.0 and 7.0 revealed two trends. At low ionic strength for a given salt, differences in CPT can be explained in terms of repulsive electrostatic interactions between protein molecules, while at higher ionic strength, differences can be attributed to hydration forces. A model is proposed for the correlation and prediction of the CPT as a function of salt type and salt concentration. NaCl was chosen as a reference salt, and CPT deviations from that of NaCl were attributed to hydration forces. The Random Phase Approximation, in conjunction with a square-well potential, was used to calculate the strength of protein–protein interactions as a function of solution conditions for all salts studied.

Effect of Salt on Temperature-Swing Adsorption of Nonionic Surfactant with Poly(Vinylmethyl Ether) Gel.

The effect of salt concentration on temperature-swing adsorption of nonionic surfactant Triton X-100 with poly(vinylmethylether) gel (PVMEG) was investigated with sodium salts of citrate, succinate, sulfate, hydrogen phosphate, chloride and nitrate. With increasing salt concentration, the amount of Triton X-100 adsorbed on PVMEG increased and the critical temperature range across which the adsorbed amount of Triton X-100 drastically changed shifted to the lower temperature side. The effects of salt type and concentration on temperature-swing adsorption process were evaluated in terms of effective adsorbed amount, midpoint temperature and temperature sensitivity. The effective adsorbed amount increased with increasing ionic strength up to a certain critical value depending on salt type, and then sharply decreased above the critical value. The dependency of midpoint temperature on ionic strength below the critical value was different from that above the critical value. The temperature sensitivity became minimum at ionic strength around the critical value .The critical ionic strength was found to be depend mainly on the valence of ion.

Effects of salts and moisture content on N 2 O emission and nitrogen dynamics in Yellow soil and Andosol in model experiments

The effects of salt type and its concentration on nitrification, N mineralization and N2O emission were examined under two levels of moisture content in Yellow soil and Andosol samples as simulated to agriculture under arid/semi-arid conditions and under heavy application of fertilizer in a glass-house, respectively. The salt mixtures were composed of chlorides (NaCl and NH4Cl) or sulphates [Na2SO4 and (NH4)2SO4] and were added at various concentrations (0, 0.1, 0.2, 0.4 and 0.6 M as in the soil solution). These salts were added to non-saline Yellow soil at different moisture contents (45 or 40 and 65% of maximum water-holding capacity; WHC) and their effects on the changes in mineral N (NH4 +-N and NO3 –-N) concentration as well as N2O emission were examined periodically during laboratory incubation. We also measured urease activities to know the effect of salts on N mineralization. Furthermore, Ca(NO3)2 solution was added at various concentrations (0, 0.1, 0.3, 0.5 and 0.8 M as in the soil solution) to a non-saline Andosol taken from the subsurface layer in a glass-house and incubated at different moisture contents (50% and 70% of WHC) to examine their effects on changes in mineral N. Nitrification was inhibited by high, but remained unaffected by low, salt concentrations. These phenomena were shown in both the model experiments. It was considered that the salinity level for inhibition of nitrification was an electric conductivity (1 : 5) of 1 dS m–1. This level was independent of the type of salts or soil, and was not affected by soil moisture content. The critical level of salts for urease activities was about 2 dS m–1. The emission rate of N2O was maximum at the beginning of the incubation period and stabilized at a low level after an initial peak. There was no significant difference in N2O emission among the treatments at different salt concentrations, while higher moisture level enhanced N2O emission remarkably.

Conformational change and aggregation of κ-carrageenan studied by flow field-flow fractionation and multiangle light scattering

The relatively novel combination of flow field-flow fractionation (FFF) and multiangle light scattering (MALS) was employed to study a nondegraded κ-carrageenan in different 0.1M salt solutions. The applicability of the technique was tested, and the effects of salt type and salt composition on the molar mass and radius of gyration were studied. A conformational ordering was induced at room temperature by switching the solvent from 0.1M NaCl (coil form) to 0.1M NaI (helix form). An approximate doubling of the average molar mass and an increase in radius of gyration was then observed, in agreement with results obtained previously using size exclusion chromatography–MALS. This increase in size was attributed to conformational ordering and to the formation of double helices. Severe aggregation was observed above 40% CsI in the 0.1M mixed salt solution of CsI and NaI. This was ascribed to the association of helices into large aggregates. For these large associates, having molar masses of several millions, a reversal of the elution order in flow FFF was detected. © 1998 John Wiley & Sons, Inc. Biopoly 45: 85–96 1998

A Simple Model for Reverse Micellar Extraction of Proteins

ABSTRACT A simple thermodynamic model is developed for the extraction of proteins with reverse micelles formed with the contact method. The model is based on the ionexchange reaction of the protein and the surfactant countenon at the reverse micellar interface. Using the equilibrium constant for this reaction and the equilibrium constants of the protein reactions in the aqueous phase, a simple expression is derived for the effects of salt type and concentration, pH, surfactant concentration, and volume ratio of two phases on the extraction. Results on the extraction of a-chymotrypsin into dioctyldimethyl ammonium chloride (DODMAC) reverse micelles are well predicted by the model. The negatively charged proteins are extracted from the aqueous phase by exchanging with the Cl∼ counterion of DODMAC at the reverse micellar interface. The presence of counterions different from chloride in the system, which are introduced through addition of a salt, has a significant effect on the extraction. The added counterions are exchanged with the chloride of the surfactant at the reverse micellar interface, therefore changing the nature of the surfactant. This change in the nature of the surfactant, in tum, alters the extraction of negatively charged proteins.

Extraction of Zwitterionic Amino Acids with Reverse Micelles in the Presence of Different Ions

The effects of salt type and concentration, of amino acid and surfactant concentrations, of volume ratio, and of solvent on the reverse micellar extraction of tryptophan and phenylalanine at their zwitterionic condition using Aerosol-OT were determined. The effect of solvent on the ion distribution was also examined. The extraction was mainly controlled by the chemical and electrostatic interactions between the amino acids and the surfactant headgroups at the active reverse micellar interface. A simple model which accounts for the effect of different variables and accurately predicts the amino acid solubilization in the reverse micellar phase is proposed.

Mechanism of growth of the open circuit insulating Oxide films on valve metals

AbstractThe kinetics of growth of the open circuit insulating oxide films on Hf, Ta, Nb, Zr and Al were studies in many salt solutions using potential and capacitance measurements. The effect of salt type and concentration, oxygen concentration, temperature and surface pretreatment on the growth kinetics were also investigated. In all cases, the potential and the reciprocal capacitance were found to increase linearly with logarithm of time. It is assumed that the oxide film grows via the solid state mechanism under the influence of highly enough electric field strength to cause the ionic migration. The field is created as a result of the adsorption of the electrolyte anions onto the metal oxide surface. The estimated field strengths (H ≈︁ 106 V cm−1) are in favour with the proposed mechanism. The results showed also that the growth rate constant is a function of the field strength.