• Journal of Environmental Health Sciences
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• v.24 no.3
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• pp.54-62
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• 1998

20 bacterial strains capable of growing on phenol minimal medium were isolated from soil and wastewater by the enrichment culture technique, and among them, one isolate which was the best in the cell growth was selected and identified as Bacillus sp. SH3 by its characteristics. Strain SH3 could grow with phenol as the sole carbon source up to 15 mM, but did not grow in minimal medium containing above 20 mM of phenol. The optimal conditions of temperature and initial pH for growth and phenol degradation were 30$^{\circ}$C and 7.5, respectively. This strain could grow on various aromatic compounds such as catechol, protocatechuic acid, gentisic acid, o-, m-, p-cresol, benzoic acid, p-hydroxybenzoic acid, anthranilic acid, phenyl acetate and pentachlorophenol, and the growth-limiting log P value of strain SH3 on organic solvents was 3.1. In batch culture, strain SH3 degraded 97% of 10 mM phenol in 48 hours. In continuous culture under the conditions of 20 mM of influent phenol concentration and 0.050 hr$^{-1}$ of dilution rate, the treatment rate of phenol was 94%.

• Korean Journal of Food Science and Technology
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• v.35 no.4
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• pp.635-641
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• 2003

A non-thermal pasteurization technology, high Pulsed Electric Field (PEF) has been thought to be a new alternative processing technology instead of heating. The objective of this study was to examine and compare the effect of PEF and High Temperature Short Time (HTST) treatments on the physicochemical, microbiological and sensory characteristics of citrus juices. Total sugar and titratable acidity values of fresh citrus juice and two treatments were not significantly different each other at p<0.05. The concentration of vitamin C in fresh citrus juice $(31.2{\pm}0.59\;mg%)$ was not significantly different with the value of PEF treatment $(29.4{\pm}0.75\;mg%)$ but was significantly higher than the value of HTST treatment $(27.4{\pm}0.75\;mg%)$. The color values (L, a, and b) in PEF treatment were significantly lower than the fresh citrus juice, but were higher than the values of HTST treatment. Both total bacterial cell counts $(6.65\;{\pm}\;0.08\;log_{10}(cfu/mL))$ and yeast counts $(7.79{\pm}0.07\;log_{10}(cfu/mL))$ in fresh citrus juice were significantly reduced by PEF $(1.39{\pm}0.14,\;2.42{\pm}0.1\;log_{10}(cfu/mL))$ as well as HTST treatment (0, 0). PE activity of fresh citrus juice $(1.3{\pm}0.12\;units/mL)$ was significantly reduced by PEF treatment $(0.11{\pm}0.01\;units/mL)$ and was totally inactivated by HTST treatment. Sensory evaluation scores in flavor, taste and overall acceptability between the fresh and PEF treated citrus juices $(7.2{\sim}7.5)$ were not significantly different but the values of HTST treatment $(5.1{\sim}5.8)$ were lower than others. Consequently, PEF treatment is thought to be a good alternative pasteurization method for fresh citrus juice to HTST treatment due to its strong pasteurization effect, reduced destruction of nutrients and good sensory characteristics.

• Journal of the Korean Ceramic Society
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• v.40 no.1
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• pp.11-17
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• 2003

The effect of$ZrO_2$addition on the microstructure and electrical properties of Ni-Mn oxide NTC thermistors was studied. Major phases present in the sintered bodies of $Ni_{1.0}Mn_{2-x}Zr_xO_4$ were the solid solutions of Ni-Mn-Zr oxides with a cubic spinel structure and the $ZrO_2$ with a tetragonal structure. The $ZrO_2$ was formed by the partial decomposition or incomplete formation of the Ni-Mn-Zr oxides during sintering. With increasing the amount of added $ZrO_2$, the $ZrO_2$ phase increased. The relationship between log resistivity (log p) and the reciprocal of absolute temperature (1/T) of the NTC thermistors prepared was linear, indicative of NTC characteristics. The resistivity, B constant and activation energy of the thermistors increased with increasing $ZrO_2$ content.

• Korean Journal of Food Science and Technology
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• v.54 no.4
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• pp.437-444
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• 2022

This study investigated the optimal quality characteristics of sauerkraut made by adding 0.5, 1.0, 1.5, 2.0, and 2.5% (w/w) sea salt to cabbage according to the storage period. The results showed that the pH and salinity of 0.5-2.5% sauerkraut decreased, while its total acidity increased during storage. After 20 d of storage, 1.5% or less sauerkraut showed low yellowness, but high brightness and hardness. Moreover, the lactic acid bacteria in 0.5-2.5% sauerkraut maintained at least 7.06 log CFU/mL until 28 d of storage, suggesting that the lower the salt concentration, the higher were the amount of lactic acid bacteria. The coliform group was not detected after 4 d of storage. In conclusion, the quality characteristics of sauerkraut with a salt concentration of 1.5% or less were excellent until 20 d of storage at 4℃. This study provides valuable data for the safe and high-quality assessment of low-salt sauerkraut in the future.

• Journal of Food Hygiene and Safety
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• v.38 no.1
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• pp.31-36
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• 2023

This study was conducted to evaluate the efficacy of sodium hypochlorite in eliminating Escherichia coli strains from leafy green and stem vegetables, which are frequently sold at community service centers. A cocktail of non-pathogenic E. coli and enterohaemorrhagic E. coli (E. coli O157:H7) was used to artificially contaminate the vegetables (initial numbers of bacteria 7-8 log CFU/g). The contaminated vegetables were soaked in sodium hypochlorite for 5 min and then washed three times with running water. After the treatment, number of viable bacterial cells on the vegetables was estimated. Sodium hypochlorite treatment reduced the E. coli population by 1-2 log CFU/g on leafy green and stem vegetables, a significant reduction from the initial number. Further, sodium hypochlorite showed better antimicrobial efficacy for leaves with a larger surface area, less roughness, and softness. There was no significant difference in the antimicrobial effect between 100 and 200 mg/kg of sodium hypochlorite. Therefore, it is not necessary to increase sodium hypochlorite concentration than the level suggested in the school meal hygiene management guidelines. However, sodium hypochlorite treatment is not sufficient to achieve a safe level of microorganisms on leafy green and stem vegetables since they generally have a high abundance of microorganisms on their surface. Thus, an alternative cooking method for fresh leafy green and stem vegetables in summer should be developed to ensure they are safe for consumption.

• Food Science and Preservation
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• v.24 no.1
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• pp.125-133
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• 2017

This study evaluated the changes of physiochemical properties, phytochemical contents, and biological activities during the vinegar fermentation of Elaeagnus multiflora fruit. The contents of pH and reducing sugar decreased from 3.55 and 6.88 mg/mL 3.34 and 2.13 mg/mL, respectively. However the acidity increased from 0.48% to 5.48% during the vinegar fermentation. The alcohol contents increased up to a maximum value of 6.6% at 20 days, and it then decreased at the end fermentation days (2.0%). The viable numbers of acetic acid bacteria and yeasts increased from 4.32 log CFU/mL and 3.23 log CFU/mL at 10 days to 5.4 log CFU/mL and 5.5 log CFU/mL during the spontaneous fermentation, respectively. The major organic acids were acetic acid (38.84 mg/mL), lactic acid (4.92 mg/mL), and malic acid (1.51 mg/mL). The soluble phenolic and flavonoid contents increased from 0.79 mg/mL and 0.12 mg/mL of initial fermentation day to 1.22 mg/mL and 0.14 mg/mL during the spontaneous fermentation. Content of epicatechin gallate decreased from $168.1{\mu}g/mL$ at 10 days to $115.97{\mu}g/mL$. However the content of gallic acid increased from $18.52{\mu}g/mL$ to $95.07{\mu}g/mL$ during fermentation. After 60 days of the fermentation, the antioxidant and digestive enzyme inhibitory activities were 71.35% (DPPH), 79.27% (ABTS), 68.72% (${\cdot}OH$), 85.42% (${\alpha}$-glucosidase), 52.12% (${\alpha}$-amylase), and 53.66% (pancreatic lipase), respectively.

• Geophysics and Geophysical Exploration
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• v.26 no.3
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• pp.138-149
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• 2023

In geoscience and engineering the geological characteristics of sediment strata is crucial and possible if reliable borehole logging and seismic data are available. To investigate the characteristics of the shallow strata in the Korea Strait, laboratory sonic logs were obtained from deep borehole data and seismic section. In this study, we integrated and analyzed the sonic log data obtained from the drilling core (down to a depth of 200 m below the seabed) and multichannel seismic section. The correlation value was increased from 15% to 45% through time-depth conversion. An initial model of P-wave impedance was set, and the results were compared by performing model-based, band-limited, and sparse-spike inversions. The derived P-impedance distributions exhibited differences between sediment-dominant and unconsolidated layers. The P-impedance inversion process can be used as a framework for an integrated analysis of additional core logs and seismic data in the future. Furthermore, the derived P-impedance can be used to detect shallow gas-saturated regions or faults in the shallow sediment. As domestic deep drilling is being performed continuously for identifying the characteristics of carbon dioxide storage candidates and evaluating resources, the applicability of the integrated inversion will increase in the future.

• The Korean Journal of Food And Nutrition
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• v.29 no.5
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• pp.698-705
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• 2016

This study aimed to evaluate the quality characteristics of Gastrodia elata Blume fermented by lactic acid bacteria after saccharifying by 3 methods including enzyme, malt, and rice-nuruk. The lactic acid bacteria (LAB), Pediococcus inopinatus BK-3, isolated from kimchi could reduce the unpleasant taste and odor of Gastrodia elata Blume. The total acidity value of Gastrodia elata fermented by LAB on the malt and rice-nuruk extract solution for 3 days was 2.23% and 2.33%, respectively. After saccharification by malt and rice-nuruk extract solution for 3 days, the viable cell number of fermented Gastrodia elata was 9.14 log cfu/mL and 9.27 log cfu/mL, respectively. The total acidity values were increased above 3.35% by malt and rice-nuruk extract solution for 8 days. Thus, the viable cell number was the highest by malt and rice-nuruk extract solution fermentation for 3 days. The amino acid content of Gastrodia elata fermented by LAB after saccharification by malt extract solution was higher than that of other saccharifying methods. The free sugar content and p-hydroxybenzyl derivatives induced by the enzyme method were higher than those of other saccharifying methods. The overall acceptability was the highest at 4.2 point in Gastrodia elata fermented by malt extract solution.

• Food Science of Animal Resources
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• v.28 no.5
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• pp.574-579
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• 2008

To develop a yogurt for sensitive consumer such as infants, children or immuno-compromised patients using gamma irradiation, the effects of gamma irradiation on the microbiological, chemical, and sensory quality in a commercial plain yogurt were investigated. No viable coliform bacteria were detected in the sample and approximately a 6 decimal reduction was achieved in the number of total aerobic bacteria by irradiation at 5 kGy. The initial population of lactic acid bacteria observed in the commercial plain yogurt was 8.95 log CFU/g. Gamma irradiation significantly reduced the initial microbial level to 6.47 and 2.85 log CFU/g after irradiation at 1 and 3 kGy, respectively (p<0.05). However, irradiation dose up to 5 kGy could not completely eliminate the lactic acid bacteria in commercial plain yogurt. pH, color, lactose and lactic acid content, and sensory quality were not affected by irradiation treatment and storage. Our results suggest that irradiation can improve the microbial quality of commercial plain yogurt without impairing the physicochemical and sensory quality.

• Food Science and Preservation
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• v.22 no.2
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• pp.225-231
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• 2015

This study was conducted to examine the physicochemical properties and micro-encapsulation process of rice fermented with Bacillus subtilis CBD2. The viable bacterial cell, pH, and amylase activity of the rice liquid culture were 7.61 log CFU/mL, pH 5.08 and 159.43 units/mL, respectively. The micro-encapsulated rice liquid culture was manufactured via spray drying with different forming agents: i.e., alginic acid 1.0% and chitosan 0.3%, 0.5%, and 1.0%. The moisture contents of the spray-dried powders were approximately 2.90~3.68%. The color of the L and a value decreased whereas that of the b and ${\Delta}E$ value increased. The particle size and outer topology of the spray-dried rice liquid culture were $48.13{\sim}68.48{\mu}m$ and globular, respectively. The water absorption index of the spray-dried powder (2.40~2.65) was lower than that of the freeze-dried powder (2.66). The water solubility index of the spray-dried powder (9.17~10.89%) was higher than that of the freeze-dried powder (7.12%). The in vitro dissolution was measured for five hours in pH 1.2 simulated gastric fluid, and pH 6.8 and pH 7.4 simulated intestinal fluids, using a dissolution tester at $37^{\circ}C$ with 50 rpm agitation. The amylase survival in the fermented rice was 85.93% through the spray-drying and it was very effectively controlled.