Addition Of Sodium Chloride Research Articles

Ultrasound-assisted water-in-palm oil nano-emulsion: Influence of polyglycerol polyricinoleate and NaCl on its stability

This study aimed to formulate a stable palm oil-based water-in-oil (W/O) nano-emulsion. Emphasis was placed on the effects of polyglycerol polyricinoleate (PGPR), medium chain triglyceride (MCT), lecithin and sodium chloride (NaCl) addition towards the stability of nano-emulsion. Among the performed analyses were mean droplet diameter (MDD), dispersity index (DI), critical micelle concentration (CMC), lipid peroxidation, viscosity, sedimentation index (SI) and surface morphology. The most stable optimized palm oil-based W/O nano-emulsion was produced using 61.25 wt% of palm oil, 26.25 wt% of MCT, 2.5 wt% of PGPR and 10 wt% of water (0.5 M of NaCl). The MDD and DI of the obtained W/O nano-emulsion were 143.1 ± 8.8 and 0.131 ± 0.094, respectively. After 2 weeks, no sedimentation was observed in W/O nano-emulsion with MDD and DI were 151.2 ± 6.5 nm and 0.156 ± 0.025 respectively. This study clearly found that polyricinoleate non-polar fatty acids of PGPR bound to non-polar fatty acids of palm oil through van der Waals intermolecular forces. While, polyglycerol polar head of PGPR interacts with water molecules through hydrogen bonding, as well as by the bound glyceride units of palm oil. The addition of NaCl further reduced MDD by 70 nm and improved the stability of nano-emulsion through electrostatic and steric repulsions attributed to the dissociation of Na+ and Cl− ions. This study aids to widen the knowledge and interest on the utilization of palm oil for the generation of W/O nano-emulsion, as well as to better understand the interaction between palm oil and PGPR/NaCl in producing nano-emulsion.

Salinidade na cultura do arroz irrigado: características agronómicas e qualidade de sementes

The aim of this study was to evaluate the effect of saline stress on different stages of rice development on agronomic characteristics and the physiological quality of seeds produced. Two concentrations of water salinity (16 and 12 mM) by the addition of sodium chloride were used. The experiment model used was a randomized block design arranged in a split-plot scheme, the plots consisted of different stages of rice development and the subplots consisted of two rice cultivars (IRGA 417 and BRS Bojuru) with four replications. On the basis of the results of these experiments, it can be concluded that the salinity negativelyaffects the agronomic characteristics and the physiological quality of seeds produced from the BRS Bojuru and IRGA 417 cultivars. The most critical rice stages for the yield and seed quality of rice cultivars were EM- from emergency (E) to harvest maturity (M), EAN- from emergency to anthesis (AN), and 35AN- from emergency to anthesis (AN). BRS Bojuru cultivar presents better performance against saline stress for the agronomic characteristics than for the physiological quality under the same conditions of cultivation.

Phase diagram of colloidal crystals of poly(methyl methacrylate) spheres in the exhaustively deionized dispersion

Phase diagram of colloidal crystals of poly(methyl methacrylate) (PMMA) spheres (100 to 300 nm in diameter) was measured precisely for the exhaustively deionized aqueous dispersion. Strong iridescent colors changed from bluish to reddish and metallic as sphere size increased at high sphere concentrations around 0.1 in volume fraction. Large single crystals, on the other hand, were recognized with the naked eyes at low sphere concentrations around 0.0005 to 0.001 especially for PMMA spheres smaller than 200 nm. The critical concentrations of melting (or crystallization), ϕc of all the PMMA spheres examined were quite low between 0.00025 and 0.00060 in volume fraction. The ϕc values were insensitive to kind (polystyrene, silica, and fluorine-containing spheres) and also to size (90~300 nm) of colloidal spheres. The ϕc value of the deionized dispersion with the coexistence of the ion-exchange resins was lowest, and that without resins was tenfold large. Addition of sodium chloride increased the ϕc values sharply. Extension of the electrical double layers forming around the colloidal spheres is most important to determine the ϕc values.

Quantifying kinetics of mineralization of carbon dioxide by olivine under moderate conditions

Global warming mitigation is an urgent issue all over the world and the mineralization for CO2 sequestration is one of the best methods to permanently store CO2 gas. The current work has developed a quantified mineralization formula through the systematic investigation of the kinetics of mineralization of a dunite containing high-grade olivine under the chemical reaction control. The effect of the most important CO2 partial pressure, addition of sodium bicarbonate, specific surface area of the olivine, addition of sodium chloride and reaction temperature can be quantified to the 1.6th, 0.8th, 0.7th, 0.34th power and 47.97 kJ/mol activation energy respectively with a relative error less than ±5%. When there was high addition of sodium bicarbonate, the effect of sodium chloride was not significant. Once the addition of sodium bicarbonate and the CO2 partial pressure were high enough, the mineralization was always controlled by dissolution of olivine. The following quantified mineralization formula has been developed. α = (1 − (1 − k0 × [S]0.7 × [PCO2]1.6 × [NaHCO3]0.8 × e(−Ea×1000/RT) × t)3) × 100%, where k0 is the correction factor, related to the mineralization capability of the material and others. The developed formula and the transformations can be applied to predict the mineralization efficiency, the necessary requirements of reaction time, required sodium bicarbonate and the relationship between the required specific surface area and CO2 partial pressure. It can be theoretically suitable for the materials where the majority are olivine and it is necessary to carry out several pre-tests to determine the value of the correction factor (k0).

Effect of Sample Diluents on the Quantitation of Basic Compounds by High Performance Liquid Chromaography

The detrimental effect of the interaction between basic analytes and silanol groups on the stationary phases during high-performance liquid chromatography (HPLC) separations has been well characterized, and many new stationary phases have been developed to minimize this effect. Similar interactions can happen between basic analytes and silanol groups on glassware surfaces during sample preparation but are often neglected. In this study, we used amitriptyline and its impurity, nortriptyline, as an example to study the effects of sample diluents on their quantitation by HPLC with four different types of glass HPLC vials. Three diluents were studied including water, 100 mM sodium chloride, and 0.1% trifluoroacetic acid. The method performance was evaluated in terms of linearity, precision and accuracy. Low sensitivity and high variability was observed for sample solutions prepared in water, which can be attributed to random adsorption of basic analytes onto the silanol groups of the glassware surfaces. Addition of sodium chloride to increase the ionic strength improved the method performance for both assay and impurity level measurements but did not completely eliminate the interaction with silanols. The most accurate and precise results across all concentration ranges regardless of HPLC vial type were obtained using 0.1% trifluoroacetic acid as the diluent.

Phase equilibrium condition measurements in carbon dioxide hydrate forming system coexisting with sodium chloride aqueous solutions

Three phase equilibrium conditions of (sodium chloride aqueous solution + carbon dioxide hydrate + vapour carbon dioxide) were measured to establish seawater desalination technology using clathrate hydrates. The three phase equilibrium condition measurements were performed at temperatures between 271.85 K and 279.05 K, and at pressures between 1.283 MPa and 3.617 MPa. The concentrations of sodium chloride aqueous solution were 0.0350, 0.0700, 0.1000, and 0.1050 in mass fraction. It was found that the equilibrium temperature difference between pure water system and each sodium chloride concentration system at the same pressure was hardly influenced by the pressure level. In addition, it was found that the equilibrium temperature depression of carbon dioxide hydrate by the addition of sodium chloride is smaller than that of ice and cyclopentane hydrate especially at the high concentration of sodium chloride.

Thermodynamic Characterization of the Dimerization of an Anionic Perylene Bisimide Dye Using Molecular Simulation

The thermodynamic signature of dimerization of an anionic di(glycyl) perylene bisimide derivative in aqueous solution is characterized using molecular dynamics simulations in explicit solvent with the aim of determining the impact of temperature, pressure, and solvent composition on the free energy of aggregation and its enthalpic and entropic contributions. The change in free energy varies only weakly with temperature independent of whether the solvent consists of pure water, an aqueous ethanol/water mixture, or an aqueous solution of sodium chloride. In agreement with experimental findings, the addition of ethanol weakens the interactions between the solute molecules, whereas the addition of sodium chloride leads to more stable aggregates. The temperature dependence of the potential of mean force can be accurately described using a simple expression derived from thermodynamic perturbation theory of first order. Molecular driving forces are discussed in terms of solute–solute and solute–solvent interactions.

Salt-Induced Phase Separation of Water and Cyclohexane within a Kaolinite Nanopore: A Molecular Dynamics Study

Using a molecular dynamics simulation, the behavior of water and cyclohexane confined in a model clay (kaolinite) nanopore (∼4–6 nm) was studied at 298.15 K and 1 atm. On a dry clay basis, the water weight concentration ranged from 6 to 30% while that of cyclohexane was kept at 14%. The formation of water bridge(s) connecting the two basal surfaces was observed at all concentrations. Upon analyzing the surface potentials using the Gouy–Chapman theory, the observation was found to be attributed to the overlapping of the positive potential (octahedral) and the negative potential (tetrahedral) of the two surfaces in the interior region of such a confined environment. The wettability of the tetrahedral sheet was found to be dependent on the water content. Larger areas of this surface would become water-wet with the increase in water concentration to minimize the contact area between the oil and water phases. Addition of sodium chloride to the aqueous phase at the concentrations of 0.1, 0.5, and 1 M substantia...

A6369 TRPV1 Activation Attenuates High-Salt Diet-Induced Vascular Fibrosis Via Inhibition Of TGF-β1 Signaling

Objectives: To investigate the effect of capsaicin on vascular fibrosis induced by high-salt in vivo and in vitro through TGF-β1 signaling. Methods: Four-week-old male Wistar rats were randomly divided into 3 groups: normal-salt (NS)diet group (0.9% NaCl), high-salt (HS) group receiving 4% NaCl diet, and high salt plus capsaicin (HS+Cap) group receiving 4% NaCl diet in conjunction with 0.01% capsaicin for 24 weeks. The collagen deposition in aorta was evaluated with Masson's trichrome staining. The rat vascular smooth muscle cells (VSMCs) were cultured in a standard medium containing 139 mmol/L of sodium. The high-sodium medium (159mmol/L) contained additional sodium chloride. Cell viability and cycle distribution were determined by MTT and flow cytometry. The expression of PCNA, TRPV1 and fibrosis-related proteins (collagen I/III) and TGF-β1 as well as its downstream proteins (p-Smad2; p-Smad3; p-ERK1/2) were determined by Western blot. Results: High-salt augmented vascular fibrosis and cell proliferation in vivo and in vitro. This effect was associated with increased protein expression of TGF-β1 and its downstream proteins (p-Smad2; p-Smad3; p-ERK1/2). The TRPV1 expression in the HS group was lower than that in the NS group. The treatment with capsaicin attenuated the proliferative effect and fibrosis induced by high salt in vivo and in vitro. Additionally, capsaicin-treated cells and rats also displayed a decrease in the protein expression of TGF-β1 and its downstream proteins which was accompanied by the up-regulation of TRPV1 protein expression. Conclusion: The activation of TRPV1 by capsaicin attenuates the progression of high salt-induced vascular fibrosis and cell proliferation in vivo and in vitro possibly via suppression of TGF-β and its downstream regulatory signaling.

A6695 Effects of high sodium on the proliferation and phenotype transformation of rat cardiac fibroblasts cells

Objectives: To investigate the effects of high salt on the proliferation and phenotype transformation of rat cardiac fibroblasts cells. Methods: Rat cardiac fibroblasts were isolated from neonatal rat and cultured using tissue block culture method, and the growth curve was made according to MTT assay. CFs were synchronized by serum starvation for 24 h before high sodium treatment, the cells were cultured in a standard medium containing 139 mmol/L of sodium, the high sodium medium (146, 149, 152, 155, 158, 161, 164, 167, 170, 173 and 176mmol/L) contained additional sodium chloride, then continually cultured for 24 h, 48 h, 72 h and 96 h, respectively. The proliferation of CFs were measured using Cell proliferation Kit assay. Na+ concentration and action time of the most significant CFs proliferating were chosen for follow-up experiment with Na+ 139mmol/L as a control. The effect of osmotic pressure on the proliferation of CFs was confirmed by CCK-8 assay. The localization and protein expression of α-smooth muscle actin and fibronectin extra domain-A were employed by immunofluorecence staining and Western blot. Results: CCK8 assay showed that Compared with Na+ 139 mmol/L group, Na+ treatment (146∼176mmol/L) for 48 h and 72 h could significantly promote the proliferation of CFs, high- sodium (Na+ 161mmol/L) promoted rat CFs proliferation for 48 h markedly (P < 0.05), and excluding the effect of osmotic pressure on CFs. Compared with the control group, the protein levels of α-SMA, Fn ED-A were increased in high- sodium group (P < 0.05). Conclusion: High sodium can induce the proliferation of rat cardiac fibroblasts cells, the mechanism may be related to the high sodium induced cell phenotype transformation.

Dielectric relaxation spectroscopy of aqueous micellar electrolyte solutions: A novel application to infer Dukhin number and zeta potential of a micelle.

The complex permittivities of aqueous SDS solutions, with and without the addition of sodium chloride (NaCl), are measured in the frequency range from 200 MHz to 14 GHz. The SDS concentrations are chosen such that the SDS molecules aggregate to micelles. In this frequency range, the measured spectra allow for the identification of two different relaxation processes. That is, the relaxation of the water molecules at frequencies above 1 GHz and the micellar relaxation at frequencies lower than 1 GHz. It is found that the addition of NaCl to the system mostly affects the micellar relaxation process. In detail, the time constant as well as the amplitude of the relaxation decrease by adding NaCl. These effects are attributed to the change in the solution conductivity that changes the properties of the micelle's electrical double layer. We also extract the Dukhin number of the micelles as a function of surfactant and electrolyte content from the measurements. The Dukhin number is a dimensionless group that describes the influence of the surface conductivity on a phenomena. A regression between Dukhin numbers and free sodium ions is found so that all data collapses on a single curve independent of the surfactant concentration. The surface conductivity is a manifestation of the electrical double layer and we use the Bikerman equation to infer the zeta potential of the micelles. Comparison to literature data shows very good agreement and proves that dielectric relaxation spectroscopy can be engaged to infer the zeta potential of micelles. Abbreviations: CMC critical micelle concentration, DRS dielectric relaxation spectroscopy, EDL electrical double layer.

The Synergistic Effect of Chloride Ion and 1,5-Diaminonaphthalene on the Corrosion Inhibition of Mild Steel in 0.5 M Sulfuric Acid: Experimental and Theoretical Insights.

The inhibition efficiency of 1,5-Diaminonaphthalene (1,5DNA) compound was studied by itself as well as in a mixture that included sodium chloride (NaCl), noted [1.5DNA][Cl−], for mild steel in 0.5 M sulfuric acid. Gravimetric, electrochemical techniques and computational chemistry calculations were utilized for the assessment of corrosion inhibition efficiency and explanation of the mechanism involved during the corrosion inhibition process. The results show that inhibition efficiencies on mild steel increase with increase in concentration of the inhibitor and enhancement in inhibition efficiency was observed on addition of sodium chloride due to synergism. This inhibition has been attributed to the stabilization of adsorbed inhibitor film and, consequently, increasing its inhibitive properties. The [1.5DNA][Cl−] acts as mixed type inhibitor and the Nyquist curves show that with the increase in the concentration, the charge transfer resistance Rct increased. In addition, [1.5DNA][Cl−] obeyed Langmuir monolayer adsorption isotherm. Moreover, Molecular Dynamic Simulations and DFT calculations showed that [1.5DNA][Cl−] owned a higher adsorption ability.

Tripartite Relationships in Legume Crops Are Plant-Microorganism-Specific and Strongly Influenced by Salinity

This study investigated the effects of specific strains of two arbuscular mycorrhizae fungi (AMF) (Rhizophagus irregularis and Claroideoglomus claroideum) and of two plant growth-promoting bacteria (PGPB) (Rhizobium leguminosarum and Burkholderia spp.), supplied either individually or as combination of a mixture of both arbuscular mycorrhizae fungi with each bacteria on root morphology, growth and fresh grain yield in pea (Pisum sativum L.) plants. Inoculated and non-inoculated pea plants were subjected to two levels of salinity (0 and 50 mM) by the addition of sodium chloride into tap water. Prior to fresh grain harvesting the morphology of root system was analyzed and the dry matter of roots and shoots were individually measured in randomly selected plants. Fresh pods were individually harvested per each plant; fresh (green) grains were separately counted and weighted per each pod at each individual plant, and the average grain weight was calculated by dividing total grain weight of plant with the respective number of green grains. The raise of salinity in the irrigation water strongly diminished the growth of pea plants by significantly reducing weight, length, surface area and root volume of pea plants. The relationships of pea plants with beneficiary fungi and bacteria were specific to each microorganism and highly depended on the environment. We found that under saline conditions, Rhizophagus irregularis provided a better vegetative growth and a higher yield than Claroideoglomus claroideum. Although, single application of Burkolderia spp. provides a better vegetative growth than single application of Rhizobium leguminosarum the best results, in terms of growth and harvested yield, were still obtained by combined application of AM fungi with Rhizobium leguminosarum. This combination was able to sustain the average grain weight at the level of non-saline plants and provided a significantly higher yield than the control plants.

Rheological, textural and emulsifying properties of an exopolysaccharide produced by Mesorhizobium loti grown on a crude glycerol-based medium

In the present study, a new extracellular polysaccharide (EPS-M816) was obtained during the growth of Mesorhizobium loti Semia 816 on a crude glycerol-based medium. EPS-M816 precipitate mainly consisted of carbohydrates (82.54%) and proteins (11.31%), and the weight average molecular weight was estimated at 1.646 × 106 Da. The biopolymer was characterized by FT-IR and NMR spectroscopy, and was found to have typical functional groups of other rhizobial polysaccharides. Furthermore, the rheological and emulsifying properties were investigated. The EPS-M816 solution (1.0% w/v) showed typical pseudoplastic non-Newtonian fluid behavior, and the addition of sodium and potassium chloride (1 mol L−1) increased the apparent viscosity. Regarding its emulsification activity, EPS-M816 formed emulsions with different food-grade vegetable oils (soybean, rice, canola, sunflower and corn oils), showing emulsification index values over 65% in 24 h, indicative of strong emulsion-stabilizing capacity. The biopolymer was able to form gels with texture parameters similar to those reported for xanthan gum and low syneresis. Overall, these results suggest that EPS-M816 is a good candidate for application in the food, cosmetics and pharmaceutical industries as a thickening, gelling, stabilizing and emulsifying agent.

Galvanic Leaching of Seafloor Massive Sulphides Using MnO2 in H2SO4-NaCl Media

This paper reports the leaching of seafloor massive sulphides (SMS) from the Loki’s Castle area at the Arctic Mid-Ocean Ridge in sulphuric acid with manganese dioxide and sodium chloride. The results presented are of various leaching experiments conducted under different conditions in order to optimise the dissolution of copper and silver. It was shown that the main copper bearing minerals in the SMS were chalcopyrite and isocubanite, while silver could occur as an admixture in the crystallographic lattice of sulphides or as disseminated micro inclusions. Based on the results, the leaching mechanism was discussed and elucidated. It was shown that the dissolution of the SMS was mainly due to galvanic interactions between the primary marine minerals of SMS and manganese dioxide. Addition of sodium chloride promoted the extraction mechanism.

Tailor made protein based aerogel particles from egg white protein, whey protein isolate and sodium caseinate: Influence of the preceding hydrogel characteristics

Protein based aerogel particles derived from heat set whey and egg white protein hydrogels were prepared. The influence of the hydrogel preparation on aerogel properties was studied. Variations in pH, ionic strength and protein type and concentration were assessed as a means to vary hydrogel and corresponding aerogel structures in a targeted manner. An adjustment of pH of the precursor protein solution led to fragile hydrogels with obvious syneresis in the pH region around the isoelectric point. Corresponding aerogels were brittle and lacked the typically large specific inner surface area of aerogels. In an acidic environment, hydrogels were firm but also fragile. Aerogels were brittle but had a large specific inner BET-surface area. In an alkaline environment, the hydrogels were soft and elastic. Thus, resulting aerogels were mechanically stable and possessed a large BET-surface area. The addition of sodium chloride or calcium chloride to the protein solution had the same effect as lowering the pH towards the isoelectric point. The process of supercritical drying was also applied to enzymatically cross-linked sodium caseinate hydrogels with varying protein concentration. Corresponding aerogels had a smaller BET-surface area compared to heat set gels. The protein concentration did not affect the BET-surface area of the aerogel. Finally, an emulsion method was used to produce protein aerogel particles, suitable for microencapsulation purposes. All three types of protein formed single spherical aerogel particles with comparable aerogel properties to the related aerogel monolith. The properties of the protein aerogel particles may be tailored towards special needs for microencapsulation purposes in food, cosmetic or pharmaceutical applications.

The acidic ferric sulfate leaching of primary copper sulfides under recycle solution conditions observed in heap leaching. Part 1. Effect of standard conditions

Understanding the dissolution of copper from chalcopyrite is important as chalcopyrite is the most abundant copper mineral in the earth's crust. The main method for extraction of copper from chalcopyrite is by flotation concentration before being smelted and electro-refined. However, this process is not suitable for the treatment of the vast reserves of low grade chalcopyrite ores, where hydrometallurgical extraction through heap leaching is a better option. While pressure or high temperature leaching with the addition of sodium chloride or HCl have been proposed to extract copper from chalcopyrite concentrates, this process is too expensive to treat low grade copper ores. Currently the research focus to develop a treatment process involves the use of bacteria to oxidise the sulfide minerals and produce sulfuric acid. Given the slow extraction rates of this process it requires decades to extract all the copper from the mineral which would mean the leach solution would therefore be recycled during the process once the copper had been removed. While previous studies have reported the effect of leach temperature, pH (acid concentration) and Eh on copper extraction, these have only considered initial leaching conditions. Studies using recycle leach solution conditions have not been undertaken, and this is the focus of the study reported here. The recycle solution conditions were based on a simulated long term solution composition. This article is part of a series of papers that has investigated the effect on copper and iron extraction from chalcopyrite which has evaluated conditions, major species and additives under recycle leach concentrations. This article examines the effect of the conditions, specifically temperature, pH, Eh and solids density. It was determined that the temperature had the most significant effect on the copper and iron extraction while the pH, Eh or solids density had no appreciable effect on the extraction of either copper or iron under the recycle leach conditions tested. While the effect of temperature on chalcopyrite dissolution is known, the activation energy, the rate of dissolution and the degree of copper extraction is lower under these high solute or recycle concentrations. Similar observations were found when studying pyrite but this study attributed the lowering of these parameters under recycle conditions to the sulfate concentration causing a diffusion layer around the mineral particles which alters or slows the response of pH, Eh or temperature on the dissolution reaction.

Functionalizable thermoresponsive polymers synthesized from renewable 5-hydroxymethylfurfural derivative via the thiol-Michael addition reaction

Thermoresponsive copoly(β-thioether ester)s were efficiently synthesized from 2,5-furan diacrylate (2,5-FDA) via the thiol-Michael addition reaction under mild reaction conditions. The structures, compositions and thermal properties of copoly(β-thioether ester)s were analyzed by FTIR, 1H NMR, DSC and TGA. The resulting copoly(β-thioether ester)s exhibited a reversible thermal-induced phase transition in aqueous medium. The adjustment of cloud point temperatures (Tcp) were performed by varying the ratio of 2,5-FDA in the copolymers, and their values are in the range of ∼20–53 °C. Furthermore, the polymer concentration and the addition of sodium chloride influenced the Tcp. 1H NMR analysis confirmed the occurrence of Diels-Alder reaction. The Tcp decreased due to the enhanced hydrophobicity after the modification. These results indicated that the thiol-Michael addition reaction could be used to synthesize potentially biodegradable and functionalizable thermoresponsive polymers.

The Effect of Aeration and Hydrogen Peroxide on the Electrochemical Degradation of Methylene Blue Using Carbon Composite Electrodes

The effect of aeration and hydrogen peroxide to the electrolysis degradation of methylene blue using carbon composite has been done. Methylene blue is a dye which is most commonly used in the textile industry. In the coloring process, methylene blue only used about 5 %, while the remaining 95 % will be disposed of as waste. This compound is quite stable and non-degradable; hence it is very difficult to be degraded in nature and harmful to the environment. The aim of this study is to degrade methylene blue using electrochemical oxidation with the addition of sodium chloride as electrolyte and using carbon electrode. In this study, we use carbon composite in the electrolysis process. The advantages of carbon electrodes are low cost, wide potential window, inert and electrocatalysis activity for a variety of redox reaction. The study was conducted to determine the optimum result degradation of methylene blue by electrolysis method with aeration and hydrogen peroxide in the electrolysis process. The result of the analysis showed the aeration and hydrogen peroxide in the electrolysis process was shorter time electrolysis is 10 min. As a conclusion is the aeration and hydrogen peroxide can be used for improve performance to the electrochemical oxidation of methylene blue using carbon composite. This method is very simple equipment, easy operation and friendly for environmental.

Assessment of nutritional quality of cooked Swazi leafy vegetables

Swazi leafy vegetables are cheap, seasonal, locally grown and easily available, easy to propagate and store, highly nutritious food substances that are often used to supplement diets and whose nutrient content is affected by processing treatments. The effects of cooking on the nutrient composition of some Swazi vegetables were investigated. Common Swazi vegetables and some exotic cultivars were collected from the Manzini region, then cooked strictly according to Swazi traditional practice, digested and analysed for calcium, copper, iron, magnesium, manganese, potassium and zinc content using flame atomic absorption spectrophotometer and inductively coupled plasma spectrometer. The vegetables investigated were: Hibiscus escolentus [upright and exotic cultivars], Corchorius olitorus, Amaranthus spinosus, Amaranthus caudatus, Bidens pilosa, Solanum nigrum and Momordica involucrata. Brassica oleracea and Spinacia oleracea were also analysed and compared with other vegetables. Sampled vegetables were divided into two categories. All vegetables in category one were cooked without any additives. In category two Hibiscus escolentus and Corchorius olitorus were cooked with bicarbonate of soda and common salt; Amaranthus spinosus, Amaranthus caudatus, Bidens pilosa, Solanum nigrum, Brassica oleracea and Spinacia oleracea were prepared with sunflower cooking oil and salt. Only salt was added to Momordica involucrata . Results of the study show that cooking significantly (p £ 0.05) reduces zinc, calcium, iron, magnesium, manganese, potassium and copper content of all the vegetables analysed. The percent reductions were: 4.2 – 100% for zinc, 2.0 – 75.6% for calcium, 2.4 – 79.2% of iron, 1.2 – 73.2% for magnesium, 6.6 – 100% for manganese, 1.9 - 67.5% for potassium and 46.4 – 100% for copper. It was also found that addition of salt and bicarbonate of soda enhances loss of minerals. The cooked Swazi vegetables had significantly higher minerals content when compared to exotic varieties such as Brassica oleracea which lost most of the minerals when cooked. The loss of minerals in the vegetables may be due to leaching effect during the cooking process. It appears that this leaching effect is exacerbated by addition of sodium bicarbonate, sodium chloride and sunflower cooking oil. Cooking the common vegetables without additives or with small quantities of additives is, therefore, recommended. Key words : Additives, Minerals, Nutritional quality, Cooked, Swazi, Malvaceae, Amaranthaceae, Asteraceae, Solanaceae, Cucurbitaceae