• Microbiology and Biotechnology Letters
• /
• v.50 no.2
• /
• pp.211-217
• /
• 2022

Sodium hypochlorite (NaClO) is a disinfectant widely used in hospitals and food industries because of its antimicrobial activity against not only bacteria but also fungi and virus. The antibacterial activity of NaClO lies in the maintenance of a stable hypochlorous acid (HClO) concentration, which is regulated by pH of the solution. HClO can easily penetrate bacterial cell membrane due to its chemical neutrality and the antibacterial activity of NaClO is thought to depend on the concentration of HClO in solution rather than hypochlorite ions (ClO^-). In this study, we investigated the antibacterial activity of NaClO according to pH adjustment by means of time kill test and assays of Reactive Oxygen Species (ROS) and adenosine triphosphate (ATP) concentration changes before and after NaClO treatment. We also investigated that the degree of cell wall destruction through field emission scanning electron microscopy (FE-SEM). Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) exposed to 5 ppm NaClO at pH 5 exhibited 99.9% mortality. ROS production at pH 5 was 48% higher than that produced at pH 7. In addition, the ATP concentration in E. coli and S. aureus exposed to pH 5 decreased by 94% and 91%, respectively. As a result of FE-SEM, it was confirmed that the cell wall was destroyed in the bacteria by exposing to pH 5 NaClO. Taken together, our results indicate that the antibacterial activity of 5 ppm NaClO can be improved simply by adjusting the pH.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.40 no.4
• /
• pp.413-419
• /
• 1995

This study was conducted to find out the suitable NaCl concentration and temperature for investigating the varietal difference of salinity tolerance in Italian ryegrass. Seeds of 20 cultivars including 9 diploid and 11 tetraploid were exposed to eight levels of NaCl concentration ranging from 0 to 350mM under three temperature levels of 15, 20 and $25^{\circ}C$. The NaCl concentration(C50%) inhibited germination of 50% of the viable seeds for the cultivars at 15$^{\circ}C$ was 354mM, and those at 2$0^{\circ}C$ and $25^{\circ}C$ were 342mM and 325mM, respectively. There were significant correlations among C50% at three levels of temperature, and correlation coefficient for C50% between 2$0^{\circ}C$ and 15$^{\circ}C$ was higher than that between $25^{\circ}C$ and 15$^{\circ}C$ or 2$0^{\circ}C$. C50% was positively correlated only with germination speed at 10 days after sowing when the plants were exposed to 350mM NaCl at 2$0^{\circ}C$. For the germination speed at 10 days after sowing in 350mM NaCl at 2$0^{\circ}C$, the cultivars used could be classified into three groups. Wase Aoba, Bettina, E. K -11, Tetrone, Lira Sand, Tetra Florum and Billiken belonged to the tolerant group, and Tuchi Was, Wase Yutaka, Sakura Wase, Magnolia, Limella and Delita were as the semi-susceptible group, and Atalja, Barmultra, Ajax, Liberta, LM-16, Elving and Wilo were as the susceptible group.

• Korean journal of food and cookery science
• /
• v.9 no.1
• /
• pp.43-51
• /
• 1993

Buckwheat protein isolate was tested for the effects of pH, addition of sodium chloride and heat treatment on solubility, emulsion capacities, emulsion stability, surface hydrophobicity, foam capacities and foam stability. The solubility of buckwheat protein isolate was affected by pH and showed the lowest value at pH 4.5, the isoelectric point of buckwheat protein isolate. The solubility significantly as the pH value reached closer to either ends of the pH, i.e., pH 1.0 and 11.0. The effects of NaCl concentration on solubility were as follows; at pH 2.0, the solubility significantly decreased when NaCl was added; at pH 4.5, it increased above 0.6 M; at pH 7.0 it increased; and at pH 9.0 it decreased. The solubility increased above $80^{\circ}C$, at all pH ranges. The emulsion capacity was the lowest at pH 4.5. It significantly increased as the pH approached higher acidic or alkalic regions. At pH 2.0, when NaCl was added, the emulsion capacity decreased, but it increased at pH 4.5 and showed the maximum value at pH 7.0 and 9.0 with 0.6 M and 0.8 M NaCl concentrations. Upon heating, the emulsion capacity decreased at acidic pH's but was maximised at pH 7.0 and 9.0 on $60^{\circ}C$ heat treatment. The emulsion stability was the lowest at pH 4.5 but increased with heat treatment. At acidic pH, the emulsion stability increased with the increase in NaCl concentration but decreased at pH 7.0 and 9.0. Generally, at other pH ranges, the emulsion stability was decreased with increased heating temperature. The surface hydrophobicity showed the highest value at pH 2.0 and the lowest value at pH 11.0. As NaCl concentrationed, the surface hydrophobicity decreased at acidic pH. The NaCl concentration had no significant effects on surface hydrophobicity at pH 7.0, 9.0 except for the highest value observed at 0.8 M and 0.4 M. At all pH ranges, the surface hydrophobicity was increased, when the temperature increased. The foam capacity decreased, with increased in pH value. At acidic pH, the foam capacity was decreased with the increased in NaCl concentration. The highest value was observed upon adding 0.2 M or 0.4 M NaCl at pH 7.0 and 9.0. Heat treatments of $60^{\circ}C$ and $40^{\circ}C$ showed the highest foam capacity values at pH 2.0 and 4.5, respectively. At pH 7.0 and 9.0, the foam capacity decreased with the increased in temperature. The foam stability was not significantly related to different pH values. The addition of 0.4 M NaCl at pH 2.0, 7.0 and 9.0 showed the highest stability and the addition of 1.0 M at pH 4.5 showed the lowest. The higher the heating temperature, the lower the foam stability at pH 2.0 and 9.0. However, the foam stability increased at pH 4.5 and 7.0 before reaching $80^{\circ}C$.

• Korean Journal of Poultry Science
• /
• v.20 no.3
• /
• pp.125-131
• /
• 1993

This study was performed to find the desirable conditions for processing salted hard-boiled egg without cracking egg shell in NaCl solution under pressure. Among the many factors affecting saltiness of the shell egg, concentration of NaCl solution(0~40%), different salting time(0~45h) and salting pressure (0~4.5kg/$\textrm{cm}^2$) were employed to identify the permeability of NaCl into shell egg at ambient temperature. The saltiness of the shell egg was proportionally risen as concentration of NaCl solution, salting time and pressure increased. The most desirable saltiness was observed at the 0.70~1.00% of NaCl in albumen and 0.40~0.45% in yolk, Besides the saltiness, sensory evaluation of the shell egg were carried out to evaluate the quality of the salted shell egg. The effect of various concentration of NaCl solution, salting time and pressure on sensory scores of hard-boiled salted eggs showed that 20~40% of NaCl solution, 12~20 h of salting time, 3~4.5 kg/$\textrm{cm}^2$ of salting pressure were proper conditions for processing the product. These results indicate that the desirable condition to get salted hard-boiled shell egg were ; 30% of NaCl solution, 16h of salting time and 4.0kg/$\textrm{cm}^2$ of salting pressure.

• Clean Technology
• /
• v.27 no.2
• /
• pp.152-159
• /
• 2021

Volatile organic compounds (VOCs) occur in indoor and outdoor industrial and urban areas and cause environmental problems. Malodorous VOCs, along with aesthetic discomfort, can have a serious effect on the human body. Compared with the existing method of reducing malodorous VOCs, a wet scrubbing method using an electrolytic oxidant has the advantage of reducing pollutants and regenerating oxidants. This study investigated the optimal conditions for producing OCl^-, a chlorine-oxidant. Experiments were conducted by changing the type of anode and cathode electrode, the type of electrolyte, the concentration of electrolytes, and the current density. With Ti/IrO₂ as the anode electrode and Ti as the cathode electrode, OClproduction was highest and most stable. Although OCl^- production was similar with the use of KCl or NaCl, NaCl is preferable because it is cheap and easy to obtain. The effect of NaCl concentration and current density was examined, and the OCl^- production rate and concentration were highest at 0.75 M NaCl and 0.03 A cm^-2. However, considering the cost of electric power, OCl^- production under the conditions of 1.00 M NaCl and 0.01 A cm^-2 was most effective among the conditions examined. It is desirable to produce OCl^- by adjusting the current density in accordance with the concentration and characteristics of pollutants.

• Journal of Life Science
• /
• v.14 no.3
• /
• pp.396-399
• /
• 2004

This study was investigated the changes of root length, tissue structure of root tip, and dry matter production of a Dongjinbyeo (DJ) cultivar subjected to 0.4 % agar medium with various concentration of NaCl (salt stress)- and polyethylene glycol 6000 (PEG, drought stress). Root length and dry weight of DJ plant were declined along the high concentration of PEG and NaCl in rice plants. To elucidate the changes of tissue structure in root tip to PEG- and NaCl-treatments, we examined the microscopic observation of root tip in NaCl- and PEG-treated rice plants using Toluidine blue O. By Toluidine blue O staining, methyl-lignin accumulation was found in the epidermis and outer cortex of the elongation zone at an early stage of PEG treatment, whereas was found only the outer cortex of the elongation zone of NaCl-treated root tip. The epidermis of NaCl-treated root tip became soften instead of methyl-lignin accumulation. TR ratio was increased along the high concentration in PEG- and NaCl-treated rice plant as a result of inhibited root elongation under PEG- and NaCl-treatment. From these morphological changes in root stimulated by drought and salt stress, we suggest that agar medium is useful to identify tolerant variety in germination stage under stressful environments.

• Journal of Integrative Natural Science
• /
• v.4 no.2
• /
• pp.103-112
• /
• 2011

This study was carried out on 4 batch reactors to determine the specific ammonium oxidizing rate (SAOR), specific nitrate forming rate (SNFR) and inhibitory degree of nitrifying activities with saline concentrations. Under salt free condition ammonia was consumed during the reaction period within 200 min. When the salt level increased to 10, 20 and 30 g $NaClL^{-1}$ in reactor, ammonia depletion took 250, 300 and above 350 min, respectively. During concentration above 10 g $NaClL^{-1}$, there was nitrite accumulation. Also, at 30 g $NaClL^{-1}$ ammonia did not depleted and $NO_2{^-}$-N accumulated until the final reaction. Nitrate formation rates decreased with increasing salt concentration. SAOR and SNFR showed a decreasing trend as salinity concentrations were increased. The SAOR was reduced from 0.2 to 0.08 mg $NH_4{^+}$-N $g^{-1}VSS\;day^{-1}$ as the salt concentration increased from 0 to 30 g $NaClL^{-1}$. Similarly, the SNFR decreased from 0.26 kg $NO_3{^-}$-N $kg^{-1}VSS\;day^{-1}$ at saline free to 0.1 kg $NO_3{^-}$-N $kg^{-1}VSS\;day^{-1}$ at saline 30 g L-1. A severe inhibition of nitrifiers activity was observed at increased salt concentrations. The inhibition ratio of specific ammonium oxidation rates were 17, 47 and 60% on the reactor of 10, 20 and 30 g $NaClL^{-1}$ added, respectively. The inhibition ratio of specific nitrate forming rates also were inhibited 30, 53 and 62% on the reactor of 10, 20 and 30 g $NaClL^{-1}$ added, respectively. As the salinity concentrations increased from 0 to 30 mg $NaClL^{-1}$, the average MLSS concentration increased from 1,245 to 1,735 $mgL^{-1}$. The SS concentration of supernatant in reactor which settled about 30 minutes was not severely difference between concentration of salt free reactor and one of those high salt contained reactors.

• Korean Journal of Plant Resources
• /
• v.18 no.1
• /
• pp.123-130
• /
• 2005

High salt concentrations in the ginseng nursery soil environment of Korea is one of important reducing factors for the stable production of quality ginseng. These studies were accomplished for check the response on germination of ginseng seed, somatic embryogenesis of zygotic embryo, and biosynthesis of ginsenoside from ginseng hairy root against NaCl. Ratio of germination was at the $3\%\;and\;84.5\%$ on the basic media with 0.1M and free of NaCl repectedly, but $0\%$ at the upper of 0.2M NaCl. Somatic embryogenesis from zygotic embryo were the highest when immatured embryo was cultured on free of NaCl concentration, and which was intend to decrease at treatment of NaCl. However, in case of using the matured embryo, treatment of 0.05M NaCl resulted in better embryogenesis than NaCl free media. Red pigment was synthesized from ginseng hairy root cultured on the medium with various NaCl concentration(from 0.04 to 0.08M) and its pigment was analyzed as spectrum of anthocyane by spectrophoto- meter scanning. This cell line biosynthesized lots of crude saponin and total ginsenoside than other cell lines, also had 2 times of panaxadiol than panaxatriol.

• Membrane and Water Treatment
• /
• v.3 no.1
• /
• pp.63-76
• /
• 2012

Mother liquid discharged from a salt-manufacturing plant was electrodialyzed at 25 and $40^{\circ}C$ in a continuous process integrated with $SO_4{^{2-}}$ ion low-permeable anion-exchange membranes to remove $Na_2SO_4$ and recover NaCl in the mother liquid. Performance of electrodialysis was evaluated by measuring ion concentration in a concentrated solution, permselectivity coefficient of $SO_4{^{2-}}$ ions against $Cl^-$ ions, current efficiency, cell voltage, energy consumption to obtain one ton of NaCl and membrane pair characteristics. The permselectivity coefficient of $SO_4{^{2-}}$ ions against $Cl^-$ ions was low enough particularly at $40^{\circ}C$ and $SO_4{^{2-}}$ transport across anion-exchange membranes was prevented successfully. Applying the overall mass transport equation, $Cl^-$ ion and $SO_4{^{2-}}$ ion transport across anion-exchange membranes is evaluated. $SO_4{^{2-}}$ ion transport number is decreased due to the decrease of electro-migration of $SO_4{^{2-}}$ ions across the anion-exchange membranes. $SO_4{^{2-}}$ ion concentration in desalting cells becomes higher than that in concentration cells and $SO_4{^{2-}}$ ion diffusion is accelerated across the anion-exchange membranes from desalting cells toward concentrating cells.

• Korean Journal of Poultry Science
• /
• v.17 no.2
• /
• pp.127-133
• /
• 1990

This study was undertaken to find out the effect of heating time and temperature, pH and NaCl concentration on the heat stability of egg albumen gel during heat treatment. With the transient decrease at 110-$130^{\circ}C$, hardness of heat-set albumen gel was increased as the heating temperature increased. The cohesiveness showed similar trend as well. The lightness was decreased while the yellowness was increased as the heating time and temperature increased. Heat-set albumen gel showed maximum hardness at pH 4.5-5.0 and pH 9.0 High heat treatment($120^{\circ}C$, 30min) showed higher hardness at alkaline range compared to low heat treatment($96^{\circ}C$, 30min.). Color of the albumen gel was relatively dark at acidic range and bright at alkaline range. High heat treatment caused darker albumen gel at alkaline range and brighter albumen gel at acidic range. The addition of NaCl increased hardness and cohesiveness of the albumen gel and improved the lightness after high heat treatment regardless of NaCl concentration.