Partition Of Salts Research Articles

Quantitative multivalent binding model of the structure, size distribution and composition of the casein micelles of cow milk

Compatible theories describing the size distribution of milk casein micelles, the partition of milk salts and the formation of calcium phosphate nanocluster complexes are combined to provide the first quantitative model of the cow casein micelle. Complexes of caseins with calcium phosphate nanoclusters associate with each other and the remaining (free) caseins to form a stable, polydisperse distribution of micelle sizes. The micelles in the distribution have a highly hydrated coat-core structure in which the calcium phosphate nanoclusters, and caseins bound directly to them, occur only in the core whereas the free caseins are found in both the coat and core. The theory is used to describe the structure, substructure, surface potential, size distribution, and the salt and protein composition of casein micelles in a standard cow milk. Multivalent casein–casein interactions through short, linear, amino acid sequence motifs determine many aspects of casein micelle formation and stability.

The influence of cows stresses resistance on cheese yield and quality

The influence of cows stresses resistance on cheese yield and quality

The fate of heavy metals and salts during the wet treatment of municipal solid waste incineration bottom ash

Bottom ash contains unfavorable contaminants that could leach into the circulating water used for wet treatment, and its improper disposal of bottom ash could cause ecological pollution. This study was to discuss the partition of heavy metals and salts of bottom ash into circulating water and ash stockpile runoff in wet treatment plants in southern China. The leachability of bottom ash before and after the wet treatment was also investigated. The checked heavy metals Pb, Cu, and Ni and dissolved salts Cl− and SO42− show lower available fractions in leachate from the treated bottom ash than that in raw bottom ash. Circulating water is contaminated by target heavy metals, which the contents of Cu and Pb is higher than its limit for urban wastewater discharge. The circulating water owned the highest concentration of Cl− and SO42−, above10000 mg/L, and 1100 mg/L, which is far higher than the limits. The detected heavy metals, Cl− and SO42− in runoff also exceed the limits for urban wastewater discharge. Locations for bottom ash processing and storage sites should be selected to control and prevent any leaching and runoff impacts. Any runoff and circulation water should be discharged to the lined landfill’s leachate collection system or suitable industrial wastewater treatment facilities.

Salt partition, ion equilibria, and the structure, composition, and solubility of micellar calcium phosphate in bovine milk with added calcium salts

Increasing dietary calcium has been suggested to have a range of health benefits, such as reducing the risk of osteoporosis and hypertension. However, producing calcium-fortified products is challenging due to the destabilizing effect caused by added calcium. We provide new data on the effect of adding either calcium gluconate or calcium lactate at up to 50 mM on the partition of salts and the structure and solubility of micellar calcium phosphate (MCP). The empirical chemical formula of the MCP in milk with added calcium was Ca(HPO4)0.6(PO4)0.267, similar to that previously reported for the MCP in native bovine casein micelles. Ion equilibria calculations showed that the solubility of the MCP was decreased as measured by an increase in negative logarithm of the solubility constant (pKS) from 6.8 to 7.3 ± 0.1 and 7.5 ± 0.1 for milk with added calcium gluconate and calcium lactate, respectively. No substantial change in the amorphous structure of the MCP was observed by either X-ray powder diffraction or infrared spectroscopy of dried casein micelles as a result of added calcium. The conclusion is that the added calcium caused an increase in the concentration of the MCP and decreased its solubility without changing its amorphous structure or chemical composition.

The partition of salts (i) between two immiscible solution phases and (ii) between the solid salt phase and its saturated salt solution

The partition of salts between two polar immiscible solvents results from the partition of the cations and anions. Because electroneutrality rules in both phases, the partition of cations is affected by that of anions, and vice versa. Thus, the partition of a salt is determined by the chemical potentials of cations and anions in both phases, and it is limited by the boundary condition of electroneutrality. Whereas the partition of neutral molecules does not produce a Galvani potential difference at the interface, the partition of salts does. Here, the equations to calculate this Galvani potential difference are derived for salts of the general composition {text{Cat}}_{{nu_{text{Cat}} }}^{{(z_{text{Cat}} ) + }} {text{An}}_{{nu_{text{An}} }}^{{(z_{text{An}} ) - }} and for uni-univalent salts {text{Cat}}^{ + } {text{An}}^{ - } . The activity of a specific ion in a particular phase can thus be purposefully tuned by the choice of a suitable counterion. Finally, the distribution of a salt between its solid phase and its saturated solution is also presented, together with a discussion of the Galvani potential difference across the interface of the two phases.Graphical abstract

A quantitative model of the bovine casein micelle: ion equilibria and calcium phosphate sequestration by individual caseins in bovine milk.

The white appearance of skim milk is due to strong light scattering by colloidal particles called casein micelles. Bovine casein micelles comprise expressed proteins from four casein genes together with significant fractions of the total calcium, inorganic phosphate, magnesium and citrate ions in the milk. Thus, the milk salts are partitioned between the casein micelles, where they are mostly in the form of nanoclusters of an amorphous calcium phosphate sequestered by caseins through their phosphorylated residues, with the remainder in the continuous phase. Previously, a salt partition calculation was made assuming that the nanoclusters are sequestered only by short, highly phosphorylated casein sequences, sometimes called phosphate centres. Three of the four caseins have a proportion of their phosphorylated residues in either one or two phosphate centres and these were proposed to react with the nanoclusters equally and independently. An improved model of the partition of caseins and salts in milk is described in which all the phosphorylated residues in competent caseins act together to bind to and sequester the nanoclusters. The new model has been applied to results from a recent study of variation in salt and casein composition in the milk of individual cows. Compared to the previous model, it provides better agreement with experiment of the partition of caseins between free and bound states and equally good results for the partition of milk salts. In addition, new calculations are presented for the charge on individual caseins in their bound and free states.

The effect of transglutaminase treatment on the physico-chemical properties of skim milk with added ethylenediaminetetraacetic acid

The influence of transglutaminase (TG) treatment on the changes in the physico-chemical properties of reconstituted skim milk (10 wt%) with different amounts of added ethylenediaminetetraacetic acid (EDTA) (0–50 mM) was studied. The partition of salts (Ca, Mg, K, Na and inorganic phosphate) was determined experimentally by atomic absorption and emission spectroscopy, colorimetry and 31P-nuclear magnetic resonance spectroscopy, and calculated with a model of the salt partition in milk based on equilibrium thermodynamics. Hydrodynamic radius, skim milk viscosity and casein micelle medium resolution substructure were measured by dynamic light scattering, rheology, and small-angle X-ray scattering (SAXS), respectively. TG treatment of milk did not influence the partition of salts upon the addition of EDTA as TG crosslinking is unlikely to disrupt the phosphate centre motifs on the short exon-encoded amino acid sequences on caseins. However, TG treatment prevented full dissociation of casein micelles when >15 mM EDTA was added, and induced higher viscosity increase than TG-untreated milk upon addition of EDTA. In accordance with the particle sizing results, SAXS demonstrated that TG treatment reduced the extent of EDTA-induced micellar disruption, as compared to milk without TG treatment.

Effects of bile salts on glucosylceramide containing membranes

The glycolipid transfer protein (GLTP) is capable of transporting glycolipids from a donor membrane, through the aqueous environment, to an acceptor membrane. The GLTP mediated glycolipid transfer from sphingomyelin membranes is very slow. In contrast, the transfer is fast from membranes composed of phosphatidylcholine. The lateral glycolipid membrane organization is known to be driven by their tendency to mix non-randomly with different membrane lipids. Consequently, the properties of the membrane lipids surrounding the glycolipids play an important role in the ability of GLTP to bind and transfer its substrates. Since GLTP transfer of glycolipids is almost nonexistent from sphingomyelin membranes, we have used this exceptionality to investigate if membrane intercalators can alter the membrane packing and induce glycolipid transfer. We found that the bile salts cholate, deoxycholate, taurocholate and taurodeoxycholate, cause glucosylceramide to become transferrable by GLTP. Other compounds, such as single chain lipids, ceramide and nonionic surfactants, that have membrane-perturbing effects, did not affect the transfer capability of GLTP. We speculate that the strong hydrogen bonding network formed in the interfacial region of glycosphingolipid–sphingomyelin membranes is disrupted by the membrane partition of the bile salts causing the glycosphingolipid to become transferrable.

METHOD OF PREDICTION OF THERMAL CONDUCTIVITY COEFFICIENT OF WALL MATERIALS CONTAINING SALTS / SIENŲ DRUSKINGŲ MEDŽIAGŲ ŠILUMOS LAIDUMO KOEFICIENTO PROGNOZĖS METODAS

The salt presence in porous structure of wall materials causes changes in thermal conductivity. The real value of material thermal conductivity in service conditions is necessary for engineering applications. The method of prediction of the thermal conductivity coefficient for wall materials containing salt using corrective factor is presented in the paper. By means of corrective coefficients, for well-known content of moisture and salt in wall material, it is possible to calculate thermal conductivity coefficient with regard to the presence of specific salt or mix of salts in material. The corrective coefficient values were determined for different groups of salts. The partition of salts into groups was made by means of cluster analysis, in dependence on their influence on material thermal conductivity. Clustering, in data mining, is a useful tool for discovering groups and identifying interesting distributions in the underlying data. Santrauka Druskos poringųjų medžiagų sienų struktūroje sukelia jų šilumos laidumo kitimą. Tikroji eksploatacinė medžiagų šilumos laidumo koeficiento vertė būtina atliekant inžinerinius tyrimus. Straipsnyje pristatomas sienų, kurių medžiagos turi druskų, šilumos laidumo koeficiento prognozės metodas naudojant pataisos daugiklį. Naudojant pataisos koeficientus, esant tiksliai žinomam drėgmės ir druskų kiekiui sienos medžiagoje, galima apskaičiuoti šilumos laidumo koeficientą, atsižvelgus į tam tikrų druskų ar jų mišinių buvimą medžiagoje. Buvo nustatytos įvairių druskų grupių pataisos koeficientų vertės. Druskos buvo paskirstytos grupėmis pagal klasterinę analizę, priklausomai nuo jų įtakos medžiagos šilumos laidumui. Klasterių metodas yra naudinga priemonė duomenims apdoroti—grupėms atskleisti ir įdomiems duomenų pasiskirstymams rasti.

Theoretical Model for Calculating Ionic Equilibria in Milk as a Function of pH: Comparison to Experiment

Acidification is fundamental for the processing of milk into cheeses, caseins, and fermented dairy products. It is established that a pH decrease changes the ionic equilibria of milk, inducing the solubilization of micellar calcium phosphate. This study aimed to present a theoretical model calculating ionic equilibria in milk as a function of pH. From the pH and total concentrations of minerals and caseins, the model calculated the concentrations of all ionic species and their partition between micellar and aqueous phases of milk. As the pH decreased, the minerals present in the micellar phase were gradually displaced into the aqueous phase. The calculated concentrations of minerals were in a good agreement with the experimental ones determined from acidified milk. A very satisfactory accuracy of the calculations, estimated by a root-mean-square error (RMSE) value of 5% for Ca and P(i) and a slope of the plot close to a unit, was obtained. The model is proposed for the simulation of ionic equilibria and the partition of salts between the aqueous and micellar phases of milk and dairy formulations during acidification.

Heat stability and enzymatic modifications of goat and sheep milk

Heat treatments are important processes that affect the quality of milk and especially the physico-chemical and renneting properties. Goat and sheep milk are less stable to heat treatments than cow milk. Although heat-induced reactions are similar between animal species, the changes relative to temperature differences are due to differences in micellar structure, partition of salts between colloidal and aqueous phases, and protein interactions. Goat milk contains less protein and caseins but also less calcium and phosphate, approximately 1200 and 900 mg/kg, respectively, against 2200 and 1300 mg/kg for sheep milk, which affects their micellar systems noticeably. Caprine and ovine milk are also characterised by a lower colloidal stability than bovine milk. Change in pH, addition of salts (phosphate or citrate), or use of membrane technologies (e.g., change of whey protein to casein ratio) can decrease problems of heat instability. In addition to the instability of the milk itself due to heat treatments, milk enzymes are also inactivated by thermal processing, which can be used as a barometer of the effectiveness and for meeting legal requirements of, e.g., milk pasteurization by testing activities of, e.g., alkaline phosphatase (AP). However, there are considerable variations in AP contents between species, breed within species, and individual animals. The ranges of AP concentrations in goat, sheep and cow milk are 115–1300, 8300–17,300, and 1800–4750 μg phenol/ml, respectively, and are not related to the fat content in milk apparently, but rather to species uniqueness. However, in the case of incomplete inactivation of enzymes, proteolysis and lipolysis can occur and affect the quality of milk and dairy products.

A biological perspective on the structure and function of caseins and casein micelles

Caseins belong to a larger group of secreted calcium phosphate‐binding phosphoproteins that have a natively unfolded conformation. Nearly all members of the group are involved in aspects of calcium phosphate biology and nearly all have recognition sites for phosphorylation by the Golgi protein kinase. In the caseins these are often close together in the primary structure, forming the so‐called phosphate centres. Certain highly phosphorylated phosphopeptides derived from the calcium‐sensitive caseins will combine with amorphous calcium phosphate to form defined chemical complexes called calcium phosphate nanoclusters. Both the substructure of casein micelles and the partition of salts in milk can be explained quantitatively by the ability of the calcium‐sensitive caseins to sequester calcium phosphate and form nanocluster‐like structures. A simple stability rule for milk can be derived by applying equilibrium thermodynamics to the process of calcium phosphate sequestration. In principle, the stability rule can be extended to problems of instability encountered in milk‐processing operations and to the formulation of other types of high calcium foods.

Partition of Salts between N-Isopropylacrylamide Gels and Aqueous Solutions

Partition of Salts between <i>N</i>-Isopropylacrylamide Gels and Aqueous Solutions

Partition of diclofenac salts as ion-pairs: [formula omitted], N. Passerini∗, A. Fini∗∗, G. Fazio∗∗, M. Cini∗ and L. Rodriguez∗ ∗Dip. Scienze Farmaceutiche, Università di Bologna, Via S. Donato 19/2, 40127 Bologna, Italy. ∗∗ Istituto di Scienze Chimiche, Università di Bologna, Italy

Partition of diclofenac salts as ion-pairs: [formula omitted], N. Passerini∗, A. Fini∗∗, G. Fazio∗∗, M. Cini∗ and L. Rodriguez∗ ∗Dip. Scienze Farmaceutiche, Università di Bologna, Via S. Donato 19/2, 40127 Bologna, Italy. ∗∗ Istituto di Scienze Chimiche, Università di Bologna, Italy

Combined Effect of a Lecithin and a Bile Salt on Pancreatic Lipase Activity

Lipolysis is regulated by the presence of amphiphilic compounds such as bile salts and lecithin, which are adsorbed at the triglyceride–water interface and therefore influence the approach of water-soluble pancreatic lipase to its insoluble substrate (emulsified triglycerides). The partition of bile salts between the lipid and the aqueous phase is of prime importance in the expression of lipase activity. Lipase activity was determined as a function of different combinations of concentrations of deoxycholate and dipalmitoylphosphatidyl choline. From ζ-potential measurements, it is evident that lecithin affects the partition of bile salts, most probably by displacing deoxycholate molecules. Our results indicate that lecithin cannot be classified a priori as inhibitor or activator of pancreatic lipase. As an amphiphilic compound, lecithin exerts a synergistic effect with bile salts via the formation of mixed micelles. The final effect on lipolysis depends on the ratio of lecithin to bile salt: low ratios enhance enzyme activity, whereas high ratios lead to inhibition.

Solubilization of multilamellar liposomes of egg yolk lecithin by the bile salt sodiumtaurodeoxycholate and the effect of cholesterol — a rapid-ultrafiltration study

The solubilization of multilamellar egg yolk lecithin liposome by sodiumtaurodeoxycholate in aqueous phase was studied by ultrafiltration as a function of time, bile salt and cholesterol concentration. The corresponding equilibrium states were analysed. Complete solubilization was achieved at total bile salt/lecithin molar mixing ratios of approximately 5. The minimum ratio to start solubilization was 0.1, corresponding to a free bile salt concentration of only 5% of the critical micelle concentration (CMC). Mean equilibrium constants for the partition of bile salts between non-filterable aggregates and filterable mixed micelles and also the free bile salt concentration were determined. Sodiumtaurodeoxycholate had a higher affinity for small mixed micelles than for lamellar mixed aggregates especially in the presence of cholesterol, which reduces the degree and rate of the solubilization process. A non-homogeneous distribution of bile salts in the lipid phase was detected at low bile salt concentrations.

Interrelationships of constituents and partition of salts in milk samples from eight species

1. 1. Skim-milk samples from rat, rabbit, pig, sheep, goat, horse and man were analysed for lactose, casein and the total and ultrafilterable concentrations of the main salts. Results are compared with data for the cow. 2. 2. The ultrafiltrate concentrations of Ca and Mg were positively correlated with that of citrate and the colloidal concentrations of Ca, Mg and citrate were positively correlated with that of P i , suggesting that common, general, principles determine the partition of salts in milks. 3. 3. Casein concentration in the skim-milks was inversely related to that of lactose in accordance with a recent theoretical treatment of the principal mechanism of milk secretion. 4. 4. It is postulated that much of the interspecific diversity in milk composition can be explained by adaptations in a single secretory mechanism.

Partition of salts and their effects on partition of proteins in a dextran-poly(ethylene glycol)-water two-phase system

Partition of salts and their effects on partition of proteins in a dextran-poly(ethylene glycol)-water two-phase system

Some Observations on the Partition of Na + and K + into a Lipid Phase

It is likely that sodium and potassium must traverse a lipid membrane surrounding cells and that this membrane has to do with intracellular cation selection. Electrolyte theory is inadequate to predict the partition of salts of these cations between water and a lipid phase. The data obtained here demonstrate the partition and the cation selection to be a function of the anion species (or ionized lipid), the solvent and the presence of the unionized form of the lipid. Specificity in lipid partition is not synonymous with the cation specificity in precipitation of ionic crystals.