• Korean Journal of Ecology and Environment
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• v.42 no.1
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• pp.9-18
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• 2009

The objectives of this study were to evaluate seasonal and interannual variations of water quality and nutrient input (N, P) in Junam Reservoir, a nesting waterbody of migratory birds, over 10 years during 1998$\sim$2007 along with dynamic relations of trophic parameters using empirical models. Concentrations of COD averaged 7.8 mg $L^{-1}$ during the study, while TN and TP were $1.4\;mg\;L^{-1}$ and $83{\mu}g\;L^{-1}$, respectively, indicating an eutrophic-hypereutrophic state. Values of monthly COD had strong positive relations (r=0.669, p<0.001) with conductivity, indicating that summer rainfall resulted in an ionic dilution of the reservoir water by rainwater and contributed better water quality. One-way ANOVA tests showed significant differences (F=$5.2{\sim}12.9$, p<0.05) in TN and TP between the before and after the bird migration. In other words, nutrient levels were greater in the absence of migratory birds than in the presence of the migratory birds, suggesting a no-effect on nutrient inputs by the birds. Also, one-way ANOVA indicated no significant differences (F=$0.37{\sim}0.48$, p>0.05) in $NO_{3^-}N$ and $NH_{3^-}N$ between the before and after the birds migration. Linear empirical models using trophic parameters showed that algal biomass as CHL, had significant low correlations with TN ($R^2$=0.143, p<0.001, n=119) and TP ($R^2$=0.192, p<0.001, n=119). These results suggest that influences of nutrients on the CHL were evident, but the effect was weak. This fact was supported by analysis of Trophic State Index Deviation (TSID). Over 70% in the observed values of "TSI (CHL)-TSI (SD)" and "TSI (CHL)-TSI (TP)" were less than zero, suggesting a light limitation on the CHL by inorganic suspended solids.

• Korean Journal of Food Science and Technology
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• v.6 no.1
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• pp.24-29
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• 1974

Deep fried instant noodles, biscuits, and cookies were prepared, using the same beef tallow as their fat ingredient. In addition to wheat flour and beef tallow, the common and major ingredients, the deep fried instant noodle contained 1.5% salt before frying, the biscuits 20.0% sucrose and 10.0% nonfat milk solid before baking, and the cookies 20.0% sucrose before baking. The three products and a portion of beef tallow, which was to be used as control, were stored in an incubator at $47.0{\pm}1.5^{\circ}C$. The peroxide value and the free fatty acid value of the control and the extracted fat were determined regularly during the storage period. The fat incorporated in the biscuits exhibited far greater stability to rancidity development than that of the control with regard to both peroxide value and free fatty acid value development. However, the fat incorporated in the deep fried instant noodles and the cookies showed much poorer stability than that of the control. Factors like a deep frying process and/or the presence of a significant amount of salt in the deep fried instant noodles appeared to promote the rancidity development of the fat incorporated in the product. On the other hand, Maillard type browning reaction products in the biscuits seemed to retard effectively the rancidity development of the fat incorporated in the product.

• Korean Journal of Food Science and Technology
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• v.46 no.3
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• pp.334-340
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• 2014

Toxin-producing Bacillus cereus is the causative agent of two different types of food poisoning: the emetic and the diarrheal types. This study was conducted to investigate the presence of enterotoxin and emetic toxin genes in 263 B. cereus isolated from 619 different ready-to-eat food items. Hemolytic enterotoxins hblA, hblC, and hblD were detected in 85.6, 41.1, and 76.8%, respectively, of the B. cereus isolates. About 67.0% (175/263) of the isolates presented all of three genes. Non-hemolytic enterotoxins nheA, nheB, and nheC were detected in 100, 97.0, and 68.4% of the isolates, respectively. Approximately 90.0% (236/263) of the isolates presented all of these three non-hemolytic enterotoxin genes. Emetic toxin gene, CER, was detected in 132 of 263 (50.2%) isolates. Computer-assisted cluster analysis of Rep-PCR profiles showed a high genetic diversity among the isolates. All B. cereus isolates from food samples tested in this study carried at least 6 of 10 toxin genes.

• Journal of Food Hygiene and Safety
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• v.29 no.1
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• pp.1-5
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• 2014

Many community gardens in large cities worldwide grow vegetables; however, no information regarding the levels of sanitary indicator bacteria and prevalence of foodborne pathogens in vegetables grown in urban community gardens is available. To evaluate the microbiological quality of vegetables from urban community gardens in Korea, 530 samples (nine types of vegetable, including Chinese cabbage, lettuce, radish leaves, spinach, mustard leaves, crown daisy, leek, Korean cabbage, and chicory) were collected at 11 urban community gardens in Seoul, Korea from September through October 2012. The levels of total aerobic bacteria, Escherichia coli, total coliforms, Salmonella spp. Listeria monocytogenes, and E. coli O157:H7 were evaluated quantitatively and/or qualitatively. The mean numbers of total aerobic bacteria and coliforms were 6.3 log CFU/g (range 3.8-8.1 log CFU/g) and 4.3 log CFU/g (range 2.1-6.4 log CFU/g), respectively. Total coliforms were detected on 67% of whole vegetables. Chicory showed the highest number of total aerobic bacteria and coliforms, whereas the lowest number of coliforms was detected on leeks. E. coli was detected on 2.3% of whole vegetables, including lettuce, radish leaves, mustard leaves, and chicory; however, foodborne pathogenic bacteria were not detected on any of the vegetable samples using this highly sensitive and validated procedure. Based on these findings, the presence of coliforms and E. coli demonstrates that opportunity for improvement of microbiological safety exists throughout the produce production chain, although no major foodborne pathogens were present in vegetables grown in urban community gardens.

• Journal of Food Hygiene and Safety
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• v.32 no.6
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• pp.460-469
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• 2017

The aim of this work was to study the comparison of anti-oxidative activity in a single serving size of commercial coffees and teas. Commercial regular coffees and teas, including, brand regular coffees ($BC_A$, $BC_B$, $BC_C$, $BC_D$, and $BC_E$), green tea ($GT_A$, $GT_B$, $GT_C$, and $GT_D$), black tea ($BT_A$, $BT_B$, and $BT_C$), pu-erh tea ($PT_A$, $PT_B$, and $PT_C$), chamomile tea ($CT_A$, $CT_B$, and $CT_C$), peppermint tea ($P_A$, $P_B$, and $P_C$), polygonatum odoratum tea ($POT_A$, $POT_B$, and $POT_C$), and jujube tea ($JT_A$, $JT_B$, and $JT_C$) were assayed for the levels of ascorbic acid, caffeine, total content of polyphenols and flavonoids, and ability to scavenge free radicals, using two in vitro antioxidant assays. The scavenging abilities of $BC_A$ and $BC_C$ were $664.91{\pm}48.87mg$ ascorbic acid equivalent/serving size and $624.36{\pm}16.18mg$ ascorbic acid equivalent/serving size, respectively. The four beverage samples ($BC_A$, $BC_C$, $GT_D$, and $BT_A$) significantly reduced the production of reactive oxygen species (ROS) and intracellular oxidative stress induced by $H_2O_2$. These results suggest that the beverages possess significant radical scavenging ability, which may be due to the presence of antioxidants. Furthermore, the significant reducing level of ROS evidences the potential antioxidant effects of these beverages in human cells.

• Food Science of Animal Resources
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• v.30 no.2
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• pp.269-276
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• 2010

The objective of this study was to determine the effects of residual nitrite contents, chitosan with different molecular weight and nitrite addition on emulsified sausage during cold storage. Six types of sausages were evaluated: control, 0.5% 50 kDa chitosan (T1), 0.5% 200 kDa chitosan (T2), 150 ppm nitrite (T3), 0.5% 50 kDa chitosan+150 ppm nitrite (T4), and 0.5% 200 kDa chitosan+150 ppm nitrite (T5). Each type of sausage was tested in triplicate and assigned to one of four storage periods: 0, 10, 20 and 30 days. As the storage time increased, the presence of chitosan and nitrite resulted in decreased residual nitrite value and increased pH (in control and T2), TBARS (thiobarbituric acid reactive substance) values, and total plate counts (TPC). Values for pH, TBARS, residual nitrite and total plate counts decreased significantly in response to the addition of chitosan and nitrite relative to the control (p<0.05). T5 was redder than the control (higher CIE$a^*$) at 30 d; however, no difference in the CIE $L^*$ and $b^*$ values was observed. T5 was significantly (p<0.05) more effective at delaying lipid oxidation when compared to the other treatment groups. T5 presented TPC that was significantly lower (p<0.05) than the other groups after three days of storage. In addition, the use of chitosan and nitrite in combination had much better antioxidant and antimicrobial effectiveness than other treatment groups. In conclusion, this study demonstrates that the addition of 0.5% 200 kDa chitosan and 150 ppm nitrite in combination with emulsified sausages tended to improve antioxidative and antimicrobial effects during storage when compared to other treatment groups.

• Korean Journal of Food Science and Technology
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• v.30 no.4
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• pp.957-963
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• 1998

Several medicinal herbs, which are nontoxic and have been used widely in traditional folk medicine, were extracted and antimicrobial activity of the extracts was investigated against various foodborne pathogens or food poisioning microorganisms. The ethanol extract of Sansa, Hwangryun, Cheukbaek, and Seokchangpo showed strong antimicrobial activities against Gram postive and Gram negative bacteria, whereas those of Sakunja, Sukjihwang and Baekji had little antimicrobial activities on microorganisms tested. Among medicinal herb extracts, ethanol extract of Coptis chinensis Franch (hwangryun) showed the strongest antimicrobial activity. Antimicrobial activity of ethanol extract of Coptis chinensis Franch was not destroyed by heating at $100^{\circ}C$ for 60 min and at $121^{\circ}C$ for 30 min, which is very stable over heat. The pH effect on minimal inhibitory concentrations (MIC) of the extract of Coptis chinensis Franch indicated that MIC was reduced with increasing the pH value of the medium. The inhibitory effect of partially purified substance from the ethanol extract of Coptis chinensis Franch on the growth of Listeria monocytogenes and Staphylococcus aureus was investigated. Growth of those strains occurred at the concentration of $100{\;}{\mu}g/mL$ and were inhibited at $500{\;}{\mu}g/mL$, whereas those strains was completely inactivated in the presence of $1000{\;}{\mu}g/mL$.

• Korean Journal of Food Science and Technology
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• v.33 no.5
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• pp.567-573
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• 2001

Lactobacilli have been generally recognized as an important lactic acid bacteria present in the normal human intestinal flora. Fifty two Lactobacillus isolates were recovered from the feces of healthy Koreans whose age ranged from thirteen days after birth to 37 years. Among the isolates above, 17 isolates were tentatively identified as strains of Lactobacillus acidophilus and 3 isolates as strains of Lactobacillus casei. For their characterization, these twenty isolates were subjected to the experiments for the resistance to the artificial gastric juice, pH2.5 and bile salt. Interestingly, 3 strains survived pH 2.5 after 3 hour incubation in the artificial gastric juice with more than 75% of survival rate. L. acidophilus a-4 had the highest survival rate of 100%. Four strains including L. acidophilus a-3 grew gradually in MRS broth in the presence of the artificial bile salt. Cholesterol assimilation was also tested for the 20 isolates. The result showed that cholesterol concentration of the medium was reduced by 10 Lactobacillus isolates with more than 60%, as compared to the control. L. acidophilus a-2 had the highest reduction rate of 77%. Judging from these data obtained in vitro, some isolates ware likely to reach the lower small intestine after consumption without a significant loss of viability, suggesting that they had the potential to be developed as a probiotic culture which might lower the cholesterol level in human.

• Journal of Nutrition and Health
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• v.52 no.6
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• pp.559-568
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• 2019

Purpose: This study examined the prevalence of food allergies and allergenic factors in a selected sample of children living in Seoul, Korea, along with their dietary habits, environmental factors, and diseases as risk factors for food allergy. The results of this study will provide basic data for addressing food allergies. Methods: We selected 3,004 pre-school and school-age children, aged 0 ~ 12, in the 25 districts of Seoul as the study sample. Structured self-report questionnaires were administered over a two-month period in July-August 2018, and the children's parents recorded the answers on their children's behalf. The research tools in this study included the Korean version of the questionnaire from the International Study of Asthma and Allergies in Childhood (ISAAC). Results: The physician-diagnosed prevalence rate of food allergies was 14.2%, while 20.4% of the children experienced allergic symptoms at least once and 17.4% reported symptoms within the previous 12 months. The children's symptoms included skin problems (88.1%), gastrointestinal issues (19.2%), oral issues (16.7%), respiratory issues (12.7%), and systemic issues (1.3%). The causes of allergies included eggs, peaches, milk, peanuts, and shrimps. The factors influencing the experience of food allergies were the consumption of cereal (aOR, 1.52; 95% CI, 1.09 ~ 2.10; p = 0.013), potatoes (aOR, 1.88; 95% CI, 1.33 ~ 2.65; p < 0.001), and fast food (aOR, 1.73; 95% CI, 1.10 ~ 2.72; p = 0.017). Having food allergy symptoms was associated with a higher risk of experiencing asthma (aOR, 4.22 95% CI, 3.10 ~ 5.76; p < 0.001), allergic rhinitis (aOR, 2.53; 95% CI, 2.03 ~ 3.15; p < 0.001), and atopic dermatitis symptoms (aOR, 3.56; 95% CI, 2.88 ~ 4.40; p < 0.001). Conclusion: Episodes of food allergies warrant examining regular food consumption and placing dietary restrictions through early diagnosis as these episodes may imply the presence of other allergies. Our findings offer basic insights into the patterns, prevalence and symptoms of children's food allergies in Seoul, and our findings will contribute to identifying effective interventions for food allergies.

• Economic and Environmental Geology
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• v.38 no.4 s.173
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• pp.435-450
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• 2005

The purpose of the study is to analyze the hydrogeochemical characteristics by multivariate statistical method, to interpret the hydrogeochemical processes for the new variables calculated from principal components analysis (PCA), and to infer the groundwater flow and circulation mechanism by applying the geostatistical methods for each element and principal component. Chloride and nitrate are the most influencing components for groundwater quality, and the contents of $NO_3$ increased by the input of agricultural activities show the largest variation. The results of PCA, a multivariate statistical method, show that the first three principal components explain $73.9\%$ of the total variance. PC1 indicates the increase of dissolved ions, PC2 is related with the dissolution of carbonate minerals and nitrate contamination, and PC3 shows the effect of cation exchange process and silicate mineral dissolution. From the results of experimental semivariogram, the components of groundwater are divided into two groups: one group includes electrical conductivity (EC), Cl, Na, and $NO_3$, and the other includes $HCO_3,\;SiO_2,$ Ca, and Sr. The results for spatial distribution of groundwater components showed that EC, Cl, and Na increased with approaching the coastal line and nitrate has close relationship with the presence of agricultural land. These components are also correlated with the topographic features reflecting the groundwater recharge effect. The kriging analysis by using principal components shows that PC 1 has the different spatial distribution of Cl, Na, and EC, possibly due to the influence of pH, Ca, Sr, and $HCO_3$ for PC1. It was considered that the linear anomaly zone of PC2 in western area was caused by the dissolution of carbonate mineral. Consequently, the application of multivariate and geostatistical methods for groundwater in the study area is very useful for determining the quantitative analysis of water quality data and the characteristics of spatial distribution.