Levels Of Salt Concentration Research Articles

Nitrification of an industrial wastewater in a moving‐bed biofilm reactor: effect of salt concentration

Nitrification of wastewaters from chemical industries can pose some challenges due to the presence of inhibitory compounds. Some wastewaters, besides their organic complexity present variable levels of salt concentration. In order to investigate the effect of salt (NaCl) content on the nitrification of a conventional biologically treated industrial wastewater, a bench scale moving‐bed biofilm reactor was operated on a sequencing batch mode. The wastewater presenting a chloride content of 0.05 g l−1 was supplemented with NaCl up to 12 g Cl− l−1. The reactor operation cycle was: filling (5 min), aeration (12 or 24h), settling (5 min) and drawing (5 min). Each experimental run was conducted for 3 to 6 months to address problems related to the inherent wastewater variability and process stabilization. A PLC system assured automatic operation and control of the pertinent process variables. Data obtained from selected batch experiments were adjusted by a kinetic model, which considered ammonia, nitrite and nitrate variations. The average performance results indicated that nitrification efficiency was not influenced by chloride content in the range of 0.05 to 6 g Cl− l−1 and remained around 90%. When the chloride content was 12 g Cl− l−1, a significant drop in the nitrification efficiency was observed, even operating with a reaction period of 24 h. Also, a negative effect of the wastewater organic matter content on nitrification efficiency was observed, which was probably caused by growth of heterotrophs in detriment of autotrophs and nitrification inhibition by residual chemicals.

An investigation into the effect of fabrication parameter variation on the characteristics of screen‐printed thick‐film silver/silver chloride reference electrodes

PurposeThe purpose of this paper is to show how the fabrication parameters of screen‐printed thick‐film reference electrodes have been experimentally varied and their effect on device characteristics investigated.Design/methodology/approachThe tested devices were fabricated as screen‐printed planar structures consisting of a silver back contact, a silver/silver chloride interfacial layer and a final salt reservoir layer containing potassium chloride. The fabrication parameters varied included deposition method and thickness, salt concentration and binder type used for the final salt reservoir layer. Characterisation was achieved by monitoring the electrode potentials as a function of time following initial immersion in test fluids in order to ascertain initial hydration times, subsequent electrode drift rates and useful lifetime of the electrodes. Additionally, the effect of fabrication parameter variation on electrode stability and their response time in various test media was also investigated.FindingsResults indicate that, although a trade‐off exists between hydration times and drift rate that is dependent on device thickness, the initial salt concentration levels and binder type also have a significant bearing on the practical useful lifetime. Generally speaking, thicker devices take longer to hydrate but have longer useful lifetimes in a given range of chloride environments. However, the electrode stability and response time is also influenced by the type of binder material employed for the final salt reservoir layer.Originality/valueThe reported results help to explain better the behaviour of thick‐film reference electrodes and contribute towards the optimisation of their design and fabrication for use in solid‐state chemical sensors.

The Influence of Salt Stress on the Accumulation of Na+ and K+ in Tamarix Hispida

Taking Tamarix hispida as test materials, a group of different concentrations of NaCl were then added to the pots and the salinity was maintained at 3.0(CK), 5.0, 10.0, 15.0 and 20.0 g/L. Na+ content and K+ content of different samples were analyzed by ICP-AES. This paper has studied the influence of salt stress on the content and the distribution of Na+ and K+ in Tamarix hispida and discussed the ion transport and selective absorption mechanism of plants under the salt stress. The result shows that Na+ content of Tamarix hispida were increasing prominently with increased salinity and K+ content was rising at first and then decreasing. In the same level of salt concentration, the order of Na+ content and K+ content in Tamarix hispida is leaf>root>stem, leaf is the main part of Na+ accumulation and K+ accumulation. And the stem is just a transmission channel for Na+ where does not exist the cumulative process. In different growth areas, Na+ content is always greater than K+ content. That is because Tamarix hispida is a salt secretion plant. It has expelled the excess salt in leaves outside the body through the salt glands, which will relieve the damage of Na+ on roots to a certain extent. K+/ Na+ in leaves are greater than the one in roots, which explains the salt resistance of leaf is greater than the root.

Effects of salinity and temperature on germination and seedling growth of nine medicinal plants

Salinity stress is a major environmental constraint in arid and semi-arid regions such as Iran. Excessive amounts of salt in soil severely reduce seed germination and seedling growth of crops in agricultural systems. The purpose of this research was to study the effect of temperature, salinity and their interaction on the germination and seedling growth of nine medicinal plant species including Salvia nemorosa L., Marrubium vulgare L., Hyssopus officinalis L., Origanum majorana L., Ocimum basilicum L., Nepeta racemosa Lam., Oenothera biennis L., Silybum marianum L. and Cnicus benedictus L. Treatments included three temperatures (15, 25 and 35°C) and four NaCl concentrations (0, 5.3, 8.48 and 10.6g.l-1). A completely randomized design with three replications was used. Results showed that salinity treatments had significant effect on germination percentage, germination rate, seedling growth and seedling vigor in all nine medicinal plant species. Germination percentage and germination rate of all medicinal plant species gradually declined as the concentration of NaCl increased. Significant decrease in germination percentage and germination rate was observed at higher levels of salt concentration. Ocimum basilicum L. and Salvia nemorosa L. were the only two among nine medicinal plants in this study that germinated in salinity concentration higher than 5.3g.l–1. Germination rate and germination percentage of all species, except Ocimum basilicum were adversely affected by increasing temperature to 35°C. The highest seedling vigor in most species was observed in a temperature range of 15–25°C and increasing temperature up to 35°C, strongly decreased it. The interaction effect of temperature and NaCl concentration on final germination in all species was significant, indicating that germination response to salinity depended on temperature. The inhibitory effect of high salinity on final germination, germination rate, seedling growth and seedling vigor was greater at 35°C than at 15°C.

Effect of acidification and salt concentration on two black brined olives from Sicily (cv moresca and giarraffa)

In the present work the effects of different brining treatments on mature table olives during natural fermentation were evaluated. The considered olive cultivars are typical of Sicily: Moresca and Giarraffa. They were harvested at pigmented state. The carpological data revealed their good quality as table olives. Natural fermentation was performed with or without acidification up to pH 4, and at 8% and 15% salt concentrations. The physical, chemical and microbiological changes in olives and brines were monitored throughout the processing period. The acidification affected and selected the microbial population and maintained the low pH necessary for the hygienic safety of the product. In fact, in Moresca brines,the lactic acid bacteria totally disappeared after 60 days of fermentation while in Giarraffa they maintained their presence in the brines up to 180 days with a value between 10 4 UFC/mL and 10 6 UFC/mL, depending on the salt concentration. The microbial population was also affected by the polyphenol content, which was different between the cultivars. The color of olive fruits was greatly influenced by acidification and less by salt concentration. The addition of salt showed a different influence on the studied cultivars, in fact only the chemical analyses of Giarraffa showed a significant difference between the two levels of salt concentration.

GREEN SALAD PRODUCTION IN SOILLESS CULTURE UNDER SALINE IRRIGATION PRACTICE

This study was carried out under protected conditions, using soilless culture inert substrates: Pozzolana (PZ), Gravel (GR) and Perlite (PR) to evaluate the possibility of using saline water as an irrigation source for producing the green salad lettuce variety 'Delia' (winter variety), and endive variety 'St. Levrent Midori' (spring variety). Mean daily water consumption (L m -2 day -1 ) varied with crop variety and substrates; higher values were found for plants grown on PZ (1.2 and 4.4) than those for plants grown on GR (0.6 and 2.3) and PR (0.8 and 3.5) for lettuce and endive varieties, respectively. The pH of drained nutrient solution was with an average value of 7.9 for lettuce and 8.5 for endive, while the EC-values were around 4.0 for lettuce and 4.5 for the endive variety. The pH values of the investigated substrates for both varieties showed a high value (8.7) for the GR exceeding the ones around 8.1 reached in PZ and PR. Regarding the EC-values, two pictures appeared under successive irrigation with saline water: the first, gradual increments in the EC-values of the collected drained nutrient solution reaching 4 dS/m and 4.5 4 dS/m for lettuce and endive varieties respectively and the second, regarding the substrates showing no changes in its EC-values, being more or less equal to their initial values. This clearly indicates that with the use of inert substrates, the accumulated salts due to frequent irrigation with saline water could be easily leached out, keeping the growing media at a relatively low salt concentration level, indicating the high potentiality of using saline water (EC=4 dS/m) for the production of green salad. The plant growth parameters did behave similarly under the different investigated substrates for both varieties. The yield of lettuce was nearly three times greater than that of endive (2.14 and 0.83 kg m -2 , respectively); for both varieties higher yields were observed on PZ and lower on GR. The yield on PR was intermediate.

Salinity Effects on Yield and Yield Components of Contrasting Naked Oat Genotypes

ABSTRACT Global crop production systems are challenged by the increasing areas of saline soil in arid and semi-arid regions. Two naked oat (Avena sativa L.) lines (‘VAO-7’ and ‘VAO-24’) with distinct seedling tolerance to salinity were subjected to six levels of salt concentrations in a controlled greenhouse, and the response of yield and yield components to salinity stress was determined. The salt treatments 50, 100, 150, 200, and 250 mM sodium chloride (NaCl) (corresponding to EC: 3.42, 6.74, 9.66, 12.40, 15.04 dS m−1) imposed through modified Hoagland solution. Plain Hoagland was used as control. Complete nutrient elements were provided during the entire growth period. At maturity, the number of tillers with emerged heads was counted; the plant was then harvested and separated into shoots, seeds, and roots. Both plant height and days to maturity were shortened with increasing salt stress. Among the yield components, spikelet, tiller number, and grain dry weight per plant were significantly reduced by increasing salt concentration. Number of spikelets and grain weight per plant were the most salt-sensitive yield components. Thousand grain weight also varied as salinity stress increased. Harvest index remained relatively unchanged until the salinity reached 150 mM and higher. Our data indicate that grain yield reduction in oat due to salinity stress is associated with reduced number of grains per plant and mean grain weight.

Breeding for salinity resistance in mulberry (Morus spp.)

Soil salinity is one of the major abiotic stresses that reduce agricultural productivity. The levels of salt concentration that are inimical to plant growth have already affected more than one-third of the irrigated land in the world. In order to utilize the vast saline costal lands present in sericulturally important countries in Asia, attempts have been made to develop salt resistant varieties in mulberry. Controlled crosses were made between salt resistant parents that were identified through both in vitro and in vivo screening. Ripened fruits were harvested, and the seeds extracted were germinated on agar-agar containing MS basal medium with 1.25% NaCl. Young seedlings were rescued and nurtured under normal growth conditions. Mature seedlings were transferred to field. Based on comparative performance on survival and growth under salinity, three hybrids namely SR1, SR2 and SR3 were selected and were subjected to detailed investigation using C776 as control. SR3 outperformed other hybrids and the control, hence, was selected for large scale field testing. The encouraging results have tremendous implications on expanding sericulture industry into the costal saline areas in tropical and subtropical regions in Asia.

Responsiveness of κ-carrageenan microgels to cationic surfactants and neutral salts

The objective of this study was to examine the responsiveness of chemically cross-linked κ-carrageenan microspheres to different types of neutral salt electrolytes as well as to surfactants of varying chain lengths. In the presence of increasing salt concentration microsphere size changed radically from D[4,3] values of 320 μm to approximately 160 μm. The level of salt concentration needed to bring about this change varied depending on electrolyte type. This common behaviour was attributed to the difference in free cationic counter-ions concentration between the inside and outside of the microsphere and can be explained due to the effect of the Donnan equilibrium. The rheological properties of these microgels in their swollen and collapsed states were also explored with results showing that the collapsed microspheres had a greater impact on the viscosity of the system probably as a result of some aggregation of the collapsed microgels at rest due to surface charge screening at these high salt concentrations. The effect of surfactant on microsphere size showed a dramatic drop in D[4,3] values from 320 μm to approximately 120 μm for BAC, DoTAB, MTAB and CTAB at specific critical concentrations. This critical aggregation concentration was found to increase linearly on a log–log scale with the critical micelle concentration of these surfactants in water, indicating that the alkyl chain length of the surfactants had an effect on the critical aggregation concentration.

INFLUÊNCIA DA COMPOSIÇÃO DO MEIO DE CULTIVO E DO TIPO DE EXPLANTE NA MICROPROPAGAÇÃO DO PORTA-ENXERTO DE Prunus sp. ‘GXN-9’

Objetivou-se estudar a composição de diferentes meios de cultura, concentrações de BAP e tipos de explante, na multiplicação in vitro do porta-enxerto ‘GxN-9’, como também a influência desses fatores na ocorrência de vitrificação. Explantes basais cultivados em meio QL e WPM apresentaram as melhores respostas para porcentagem de brotação (80%). O número de brotações por explante também foi maior com explantes basais, porém apenas aqueles cultivados no meio QL (3 brotações por explante). Os meios QL e WPM permitiram obter o melhor desempenho de crescimento das brotações formadas, para ambos os tipos de explante. Contudo, explantes basais cultivados em meio QL, apresentaram 55% de vitrificação, ao passo que explantes provenientes do meio WPM, não apresentaram esta anormalidade. Concluiu-se que a redução na concentração de sais com adição de 0,5 mg dm-3 de BAP reduz a vitrificação, promovendo aumento no crescimento das brotações, sem influenciar na formação das mesmas.

Germination and reproductive biology in salty conditions of Asplenium marinum (Aspleniaceae), a European coastal fern

Although there are several species of ferns that are important components of many coastal ecosystems, the adaptations that allow these species to live in salty conditions have been studied only in two Acrostichum species. We have studied the effects of salt on germination, development of the gametophyte and sexual expression of the fern Asplenium marinum, which lives on coastal cliffs of Europe. Cultures at four different levels of salt concentration, 0%, 0.98%, 1.96% and 3.26%, were established for this purpose. Salt caused a significant delay in spore germination, and prevented it completely at high concentrations (3.26%). However, spores were able to recover germination ability after a period of seawater incubation once salinity concentrations decreased. Variable salinity conditions are a typical feature of sea cliffs where halophytes can grow. A salty culture medium also affects the development of the prothalli. Higher salinity of the substrate produced a significant decrease in gametophyte sizes, and affected the development of gametangia as well. Only males were found in a 0.98%-salt medium, and no gametangia were observed in cultures at 1.96%-salt medium. Recovered spores after one and a half month in high salinity concentration, 3.26%, were able, when transplanted to 0%-salt medium, to develop normal sexual prothalli, and this occurred in a shorter time than spores without any prior treatment. A. marinum can be considered as a halophyte fern that is able to germinate and grow in salty conditions. But it takes advantage of rainy periods that cause decrease of salt concentration, which seems to be important in particular for gametangia development and fertilization.

SOLUBILITY OF QUAIL (COTURNIX COTURNIX JAPONICA) EGG WHITE PROTEIN

ABSTRACT This work evaluated the influence of different values of pH (3.0, 4.6, 6.0, 8.0, 9.0 and 10.0) and salt concentrations (0.05, 0.1, 0.2, 0.35 and 0.5) mol/L on the solubility and density of quail (Coturnix coturnix japonica) egg white proteins for three types of salts (NaCl, Na2SO4and [NH4]2SO4). The experiment was carried out in a completely randomized design, using six pH values, five salt concentration levels and two repetitions. The variations in pH and salt concentration values had a significant effect on the protein solubility data. The highest solubility value (99.40 g/100 g) was obtained in the system containing NaCl (0.1 mol/L), at pH 3.0. The lowest solubility value (63.46 g/100 g) was obtained in the system containing Na2SO4 (0.5 mol/L), at pH 8.0. Under the tested conditions, the aqueous solutions of Na2SO4at 0.5 mol/L and pH 8.0 might lead to a higher protein extraction.PRACTICAL APPLICATIONSDetermination of protein solubility data are relevant for the food industry and for academic researchers, because they are necessary (1) to define the processing conditions of foods containing different protein sources, (2) to obtain protein concentrates, (3) for the development of the extraction and purification processes of proteins with high aggregate value, such as quail egg white proteins, and (4) to use in the acquirement of other functional properties of foods.

Effects of Saline and Sodic Stress on Yield and Fatty Acid Profile in Sunflower Seeds

Among the objectives concerned in this research, much importance has been attached to the assessment of the influence of soil type, irrigation water quality and leaching requirement on the production and composition in fatty acids of sunflower oil. The trial was run in 2001 on a sunflower crop (cv. HS 90) grown in cylindrical pots at the Campus of Bari University (Italy). 36 treatments obtained from the factorial combination of two clay soils with nine types of brackish water and two leaching fractions (10 and 20%) were compared. The nine types of irrigation water were obtained by dissolving the proper amounts of NaCl and CaCl2 in de-ionized water, according to the factorial combination of three salt concentration levels (0.01, 0.032 and 0.064 M) with three sodium levels (SAR = 5, 15 and 45). At ripening the main yield traits, oil yield and acid composition of seeds were analysed. At the highest salinity level about 70% yield reduction, in terms of seeds per plant was observed. The oil yield and the final acid composition of seeds were significantly affected by soil type, leaching requirement, salinity and the SAR levels of irrigation water. A progressive decline in oil yield was recorded as the salt concentration and sodium level of irrigation solutions increased. As to the fatty acid composition, a gradual increase in oleic and linolenic acid content and a corresponding decrease in the other fatty acids were found as the salinity and sodium levels of irrigation water increased. The oleic/linoleic acid ratio too increased as the salinity increased. The salt and sodium-induced stresses of irrigation water reduced the seed and oil yields while still favouring a progressive increase in the oleic acid content and a slight decrease of linoleic, palmitic and stearic acids, thus improving oil quality. The results point out both the influence of the soil and the positive effect of sodium and salt stress and of the leaching fraction on the food quality of sunflower oil.

Open fibre reinforced plastic (FRP) flat plate collector (FPC) and spray network systems for augmenting the evaporation rate of tannery effluent (soak liquor)

Presently, tanneries in Tamilnadu, India are required to segregate the effluent of soaking and pickling sections from other wastewater streams and send it to shallow solar pans for evaporation to avoid land pollution. A large area of solar pans is required for evaporating the water in the effluent at salt concentration in the range of 4–5%. An experimental study has been made by using fibre reinforced plastic flat plate collector (FRP–FPC) and spray system in a pilot plant with a capacity to handle 5000 l per day, which increases the evaporation rate. After increasing the salt concentration level to near saturation limit, the concentrated liquid was sent to conventional solar pans for its continued evaporation and recovery of salt. In this improved system, the rate of evaporation was found to be 30–40% more than that in the conventional solar pans. The performance is compared with the theoretically simulated performance.

Spreading of brine waste discharges into the Gulf of Oman

The effect of a tidally oscillating flow in dispersing brine waste discharge into the sea is investigated using a two-dimensional advection-diffusion equation. As a seawater desalination plant is continuously disposing of brines at a constant rate, unacceptably high salinity in coastal water on both sides of the outfall are created due to the flow reversals. It is found that by building a longer outfall, such potential environmental impacts may be reduced. Other discharge strategies that minimize the salt concentration levels at the beach are discussed.

Respon beberapa Varietas Padi terhadap Stress Garam

A study on the Responses of Several Rice Varieties toward Salt Stress has been carried out with a view to: 1) study the effect of salt stress on the physiological and anatomical responses of several rice varieties; 2) determine salt tolerant rice variety(ies). Research results showed that there were both physiological and anatomical changes on salt-stressed rice. Those changes were determined by the level of salt concentration given. The higher the concentration the more obvious the changes appeared. There was a dramatic decrease in the total chlorophyll content of the salt-stressed leaf, coupled by a sharp decrease in the chlorophyll a/b ratio. Salt stress also resulted in the decrease in mesophyll thickness, and in turn leads to the decrease of leaf’s length and width. In general, salt stress resulted in the decrease of plant growth, as indicated by the decrease of plant’s fresh and dry weights, eventual plant’s death was therefore imminent. The rice varieties used were sensitive to salt stress since an exposure of 50 mM NaCl has already resulted in the interference of rice growth.

Analysis of RF heating and sample stability in aligned static solid-state NMR spectroscopy

Sample instability during solid-state NMR experiments frequently arises due to RF heating in aligned samples of hydrated lipid bilayers. A new, simple approach for estimating sample temperature is used to show that, at 9.4 T, sample heating depends mostly on 1H decoupling power rather than on 15N irradiation in PISEMA experiments. Such heating for different sample preparations, including lipid composition, salt concentration and hydration level was assessed and the hydration level was found to be the primary parameter correlated with sample heating. The contribution to RF heating from the dielectric loss appears to be dominant under our experimental conditions. The heat generated by a single scan was approximately calculated from the Q values of the probe, to be a 1.7 °C elevation per single pulse sequence iteration under typical sample conditions. The steady-state sample temperature during PISEMA experiments can be estimated based on the method presented here, which correlates the loss factor with the temperature rise induced by the RF heating of the sample.

Mathematical modeling of mass transfer in osmotic dehydration of onion slices

The study on osmotic dehydration of onion slices was carried out in order to remove the moisture prior to the further mechanical drying. Three salt concentration levels (5%, 12.5% and 20%), three temperature levels of osmotic solution (28 °C, 43 °C and 58 °C) and the observations on weight loss and solid gain were taken at an interval of 5 min up to first half an hour followed by interval of 10 min for next 1 h. The sample to solution ratio of 1:5, agitation of 100 shakes per minute, sample thickness of 4 mm and 0.2% potassium metabisulphite mixed with osmotic solution were used for the study. A two-parameter mathematical model developed by Azuara et al. was used for describing the mass transfer in osmotic dehydration of onions slices. The effect of time on mass transfer kinetics was investigated and the constants of two-parameter model and final equilibrium points for moisture loss as well as solid gain were found. The effect of solution concentration and solution temperature was also studied and it was found that equilibrium moisture loss and solid gain are related to solution concentration and solution temperature logarithmically. The optimum conditions of osmotic dehydration for further drying were found to be 20% salt concentration, 28 °C solution temperature and 1-h of osmosis.

Salt and nitrate concentrations in the surface waters of the CR-V irrigation district (Bardenas I, Spain): diagnosis and prescriptions for reducing off-site contamination

The return flows from irrigated agriculture may increase the salt and nitrate concentrations of the receiving water bodies, limiting their agricultural, industrial, urban and ecological uses. The objectives of this study are (i) to analyze the sources and levels of salt and nitrate concentrations in the surface waters of the irrigation district n° V of Bardenas I (CR-V), and (ii) to prescribe management practices aimed at protecting the quality of water resources. The electrical conductivity (EC) and nitrate concentration ([NO 3 −]) were measured in water samples collected in 28 drainage ditches of CR-V and in eight points along the Riguel River (the main drainage outlet for CR-V) in 14 dates of the 1999–2000 hydrological year. Drainage waters were moderate in salts (year-average EC=0.87 dS/m) and high in nitrates (year-average [NO 3 −]=55 mg/l), and both of them increased during the non-irrigation season. The lowest EC and [NO 3 −] in the Riguel River were measured at the entrance of CR-V and during the April–September irrigation season (season-average=0.45 dS/m and 2 mg/l, respectively), and attained the highest values at the river outlet (end of CR-V) and during the October–March non-irrigation season (season-average=1.55 dS/m and 50 mg/l, respectively). Salt loadings at the river outlet were correlated with river flows ( P<0.001), but nitrate loadings were independent of flows ( P>0.05) due to the higher nitrate variability in drainage waters. The unitary annual upper limit load emissions from CR-V were 7.2 t total dissolved salts/ha and 59 kg NO 3 −-N/ha. The optimization of nitrogen fertilization, the improvement of irrigation efficiency and the internal reuse for irrigation of the low EC-high NO 3 − drainage waters are the key management strategies for decreasing salt and nitrogen load emissions from CR-V and protecting the quality of the receiving water bodies.

Effect of pH and Sodium Chloride on Wheat Flour Dough Properties: Ultracentrifugation and Rheological Measurements

Salt linkages, electrostatic effects, and modified water structure are important for the properties of gluten, wheat flour dough, and baking (Belitz et al 1986). These effects have been studied at various levels of salt concentration, pH, and ion strength (Doguchi and Hlynka 1967; Salovaara 1982; Kinsella and Hale 1984; Holmes and Hoseney 1987 Preston 1989; He et al 1992). Sodium chloride usually shows a strengthening effect on dough properties and a decrease in farinograph absorption (Salovaara 1982; Preston 1989). The opposite effect was found for chaotropic anions at higher salt concentrations, when the effect of neutral salts of the lyotropic series was investigated (Kinsella and Hale 1984; Preston 1989). In baking experiments, these effects are not always observed, probably due to the adjustment of water content to a constant dough mixing resistance (Salovaara 1982). On the other hand, improved baking quality for sodium chloride supplemented doughs has been reported (He et al 1992). Doguchi (1967) reported a linear and moderately increasing relationship between farinograph maximum consistency of Gluten and pH (4.5-6.0). In a later study, the loaf volume of baked bread also increased over the same pH region but decreased at higher pH values (Holmes and Hoseney 1987). Earlier studies showed that the fractions obtained by Ultracentrifugation of dough are sensitive to wheat cultivar, dough water content (Larsson and Eliasson 1996a), mixing time. ascorbic acid, and lipid content (Larsson and Eliasson 1996b). In the present study, the effect on dough properties of sodium chloride at concentrations related to baking and the effect of pH related to those observed in dough prepared with sour dough are reported. Dough properties are characterized by the fractionation of dough in ultracentrifugation and rheological measurements at small oscillating deformation.