• Clean Technology
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• v.25 no.1
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• pp.14-18
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• 2019

In general after the etching process, waste etching solution contains metals. (ex. Nickel (Ni), Chromium (Cr), Zinc (Zn), etc.) In this work, we proposed a recycling process for waste etching solution and refining from waste liquid contained nickel to make nickel metal nano powder. At first, the neutralization agent was experimentally selected through the hydrolysis of impurities such as iron by adjusting the pH. We selected sodium hydroxide solution as a neutralizing agent, and removed impurities such as iron by pH = 4. And then, metal ions (ex. Manganese (Mn) and Zinc (Zn), etc.) remain as impurities were refined by D2EHPA (Di-(2-ethylhexyl) phosphoric acid). The nickel powders were synthesized by liquid phase reduction method with hydrazine ($N_2H_4$) and sodium hydroxide (NaOH). The resulting nickel chloride solution and nickel metal powder has high purity ( > 99%). The purity of nickel chloride solution and nickel nano powders were measured by EDTA (ethylenediaminetetraacetic) titration method with ICP-OES (inductively coupled plasma optical emission spectrometer). FE-SEM (field emission scanning electron microscopy) was used to investigate the morphology, particle size and crystal structure of the nickel metal nano powder. The structural properties of the nickel nano powder were characterized by XRD (X-ray diffraction) and TEM (transmission electron microscopy).

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.5
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• pp.102-108
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• 2019

Melaleuca alternifolia contains terpineol-4, cineol, sesquiterpenes etc., and has a germicidal effect and skin moisturizing effect. It also has the characteristics of relieving acne inflammation, treating dandruff, relieving pain, and relieving depression. In this study, an antimicrobial substance extracted from tea tree using an organic solvent (methanol, dichloromethane, ethyl acetate) and hydrothermal extraction method. And confirmed the antimicrobial activity of each extract. In order to verify the antimicrobial activity, nine pathogenic bacteria (Bacillus cereus, Bacillus subtilis, Listeria monocytogenes, Enterococcus faecalis, Staphylococcus aureus, Klebsiella pneumoniae, Escherichia coli, Salmonella typhimurium, Pseudomonas aeruginosa and Vibrio parahaemolyticus) were used. The antimicrobial activity of each extracts were confirmed by the commonly used disc diffusion method. The results showed that the fraction extracts of ethyl acetate and methanol had antimicrobial effects against V. parahaemolyticus and S. aureus. Using these results, we confirmed the antimicrobial activity of each fraction extracts and hot water extracts against V. parahaemolyticus. After the treat of samples, we confirmed at over 99.9 % of antimicrobial activity. In case of antifungal activities, we confirmed of preservation effect during over 45 hours. Based on the results of this research, further studies will be conducted to confirm the possibility of development as a new antimicrobial agent.

• Journal of Food Hygiene and Safety
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• v.37 no.6
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• pp.373-384
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• 2022

Fluoxastrobin a fungicide developed from Strobilurus species mushroom extracts, can be used as an effective pesticide to control fungal diseases. In this study, we optimized the extraction and purification of fluoxastrobin according to its physical and chemical properties using the QuEChERS method and developed an LC-MS/MS-based analysis method. For extraction, we used acetonitrile as the extraction solvent, along with MgSO₄ and PSA. The limit of quantitation of fluoxastrobin was 0.01 mg/kg. We used 0.01, 0.1, and 0.5 mg/kg of five representative agricultural products and treated them with fluoxastrobin. The coefficients of determination (R²) of fluoxastrobin and fluoxastrobin Z isomer were > 0.998. The average recovery rates of fluoxastrobin (n=5) and fluoxastrobin Z isomer were 75.5-100.3% and 75.0-103.9%, respectively. The relative standard deviations (RSDs) were < 5.5% and < 4.3% for fluoxastrobin and fluoxastrobin Z isomer, respectively. We also performed an interlaboratory validation at Gwangju Regional Food and Drug Administration and compared the recovery rates and RSDs obtained for fluoxastrobin and fluoxastrobin Z isomer at the external lab with our results to validate our analysis method. In the external lab, the average recovery rates and RSDs of fluoxastrobin and fluoxastrobin Z isomer at each concentration were 79.5-100.5% and 78.8-104.7% and < 18.1% and < 10.2%, respectively. In all treatment groups, the concentrations were less than those described by the 'Codex Alimentarius Commission' and the 'Standard procedure for preparing test methods for food, etc.'. Therefore, fluoxastrobin is safe for use as a pesticide.

• Journal of Food Hygiene and Safety
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• v.33 no.4
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• pp.229-239
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• 2018

Currently, in Korea, a dry food simulant has not been designated for the migration testing of paper and board, food contact materials (FCMs) being used in dry foods, and foods heated at ultra-high temperature. Considering the diverse usage of FCMs, in order to secure reliable and confident safety evaluation and to overcome the non-trade barrier tariff in worldwide trade, migration testing methods of what should be more clearly defined for securing and overcoming. This article delves into the available literature on the use of $Tenax^{(R)}$ as a simulant for dry foods as well as its suitability and limitations, and examines the feasibility of its introduction into Korean FCMs regulation. Most experimental studies using $Tenax^{(R)}$ showed overestimated migration values when used in real foods, which reflects the potential of $Tenax^{(R)}$ as a dry food simulant in a worst-case scenario. However, more studies are required to optimize migration testing using $Tenax^{(R)}$ by standardizing the solvent type and the extraction method for surrogates of various FCMs and foods, and to resolve the potential drawbacks in the use of $Tenax^{(R)}$.

• Journal of Life Science
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• v.28 no.6
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• pp.738-744
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• 2018

Sasa quelpaertensis Nakai is a native Korean plant that grows only on Mt. Halla of Jeju Island. Its leaf is used for a popular bamboo tea due to its various health-promoting properties, and it has been increasingly used as food and cosmetic ingredients. To utilize the S. quelpaertensis leaf efficiently, the preparation method for phytochemical-rich extract (PRE) using the leaf's residue was previously reported, which was produced after hot water extraction. This study was undertaken to evaluate the anti-oxidant and anti-inflammatory potential of PRE and its solvent fractions. The ethyl acetate fraction of PRE (EPRE) showed higher DPPH, ABTS, and superoxide radical scavenging activities, and it effectively inhibited intracellular reactive oxygen species (ROS) and nitric oxide (NO) production in lipopolysaccharides (LPS)-stimulated RAW 264.7 cells. EPRE also induced the expression of heme oxygenase-1 (HO-1) by increasing the level of nuclear factor E2-related factor 2 (Nrf2) in a nuclear fraction. The inhibiting effect of EPRE on LPS-induced NO production was partially reversed by the HO-1 inhibitor (zinc protoporphyrin, ZPP), suggesting that HO-1 is involved in suppressing NO production. Taken together, the results suggest that EPRE has potential as a promising anti- oxidant and anti-inflammatory agent.

• Korean Journal of Food Science and Technology
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• v.39 no.1
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• pp.71-76
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• 2007

Foodborne illness caused by Noroviruses (NVs) is increasing rapidly in Korea. This study developed an effective detection protocol for NVs found in contaminated oysters and lettuce through an investigation using the major steps of virus particle separation, concentration and RT-PCR. As a surrogate model for NVs, the cultivable feline calicivirus (FCV) that belongs to the same Caliciviridae family was used. Instead of using a time-consuming ultracentrifugation method, efficient methods based on solvent extraction and PEG precipitation procedure were applied. Direct homogenization of a 25g sample of whole oyster and lettuce in 175mL PBS provided the simplicity that would be needed in the actual field of food product examination. The overnight PEG precipitation step at $4^{\circ}C$ was reduced to 3 h by placing the reaction tube in ice and by adjusting the PEG concentrations. The application of the use of chloroform and 0.2 ${\mu}m$ syringe filtration together showed a better detection efficiency than the use of chloroform alone in removing PCR inhibitors for both oyster and lettuce samples. Also, dilution of the extracted RNA solution before PCR provided increased sensitivity. The improved detection protocol developed in this study could be efficiently applied to detect FCV and most likely NVs from oysters and lettuce.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.1
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• pp.70-73
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• 2013

Solubility of oil contaminants in surfactant solutions plays an important role in selecting a suitable surfactant type for soil remediation. Solubility measurement procedures consist of making an equilibrium between surfactant solution and oil, solvent extraction using dichloromethane, and condensation for gas chromatography analysis. Solubility measurement requires time consumption and lots of materials. Interfacial tension is the contracting force between two immiscible liquids, surfactant solution and oil, and also closely related to solubility of oil. This study established a relationship between the interfacial tension and solubility of diesel fuel in surfactant solution and suggested a quick method to estimate solubility of oil in a surfactant solution by measuring its interfacial tension. The results of this study showed that the solubility of diesel fuel in surfactant solution was exponentially increased by decreasing the interfacial tension between two immiscible liquids. The solubility of diesel fuel was significantly increased under the interfacial tension conditions below 1 dyne/cm, while the solubility change was not apparent under the interfacial tension conditions beyond 5 dyne/cm. Interfacial tension measurements may allow us to quickly select an efficient surfactant and its concentration for soil remediation.

• Journal of Radiation Protection and Research
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• v.24 no.4
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• pp.187-193
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• 1999

The specific radioactivity concentrations in the coal fly ash obtained from heat producing stations in Korea were analyzed and its radiological hazard for reuse in construction purpose was evaluated. The concentrations of uranium isotopes in the real fly ash measured by TBP solvent extraction method and $\alpha$-spectrometer were found to be about 116.1 Bq $kg^{-1}$ for $^{238}U$, 5.01 Bq $kg^{-1}$ for $^{235}U$, and 121.2 Bq $kg^{-1}$ for $^{234}U$, respectively. The activity ratio of $^{234}U/^{238}U$, in the coal fly ash was in $1.04\;{\pm}\;0.03$, which is similar to that of uncontaminated Korean soil in natural conditions (1.14). The specific radioactivities of $^{226}Ra,\;^{232}Th,\;and\;^{40}K$ in the coal fly ash were also determined using $\gamma$-spectrometer with a HPGe detector The results showed that $^{226}Ra,\;^{232}Th,\;and\;^{40}K$ in the coal fly ash were in concentrations of $101.7{\sim}113.9$, $39.5{\sim}54.2\;and\;315.0{\sim}990.6$ Bq $kg^{-1}$, respectively. With the specific radioactivities obtained from $\gamma$-spectrometric measurements of the coal fly ash, its radiological hazard for reuse was evaluated. The result showed that the radioactivity of the coal fly ash was in permissible level.

• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.7
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• pp.1053-1058
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• 2003

The solvent extracts of Houttuynia cordata root, which were extracted by using several solvents with different polarities, were prepared for utility as a natural preservatives. The antimicrobial activity was investigated by disc diffusion method against 22 microorganisms consisting of food borne pathogens, food poisioning microorganisms and food-related bacteria. The extraction yields were 15.7%, 3.7%, 0.13%, 0.5% and 5.9% in ethanol, chloroform ethylacetate, butanol and aqueous fractions, respectively. Antimicrobial activities were shown in ethanol, ethylacetate and butanol fraction of Houttuynia cordata root. However chloroform and aqueous fractions showed weak antimicrobial activity against the tested bacteria. Among the four fractions, ethylacetate fraction showed the strongest antimicrobial activities against microorganisms tested, such as B. megaterium, E. coli, K. pneumoniae and S. typhimurium. The polyphenolic compounds widely occuring in the traditional medicine plants have been reported to possess high antimicrobial activity. The polyphenolic compound in ethylacetate and butanol fraction were 35.9% and 16.0%, ethanol, chloroform and aqueous fraction were 5.0%, 2.3% and 1.7%, respectively. There are some relationship between antimicrobial activity and polyphenol content in natural plants. The ethylacetate fraction could be suitable for the development of a food preservative.

• Korean journal of food and cookery science
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• v.16 no.3
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• pp.221-225
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• 2000

This study was conducted to investigate the usefulness of Perilla frutescens var. acuta as a natural spice. Volatile flavor components of dried Perilla frutescens var. acuta were extracted by supercritical fluid extraction method using diethyl ether as solvent. Essential oils were analyzed by gas chromatography (GC) and combined gas chromatography-mass spectrometry (GC-MS). Identification of volatile flavor components was based on the RI of GC and mass spectrum of GC-MS. A total of 24 components, including 4 hydrocarbons, 3 aldehydes, 8 alcohols, 4 esters, 3 acids and 2 miscellaneous components were identified in the essential oils. L-Perillaldehyde was found to be the major volatile flavor component of dried Perilla frutescens var. acuta. The masking effects of Perilla frutescens var. acuta on meaty and fishy flavor were measured by sensory evaluation. Meaty flavor was significantly reduced with the addition of 0.05%, 0.1%, and 0.2% Perilla frutescens var. acuta. The addition of 0.1% and 0.2% powdered Perilla frutescens var. acuta also reduced the fishy flavor of mackerel.