• Korean journal of food and cookery science
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• v.4 no.1
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• pp.53-57
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• 1988

To obtain basic data for the development of domestic tea manufacture, the physico-chemical properties were analyzed. The content of crude fiber in domestic black tea was abundant of 50%, as compared with those in Sri-Lanka's black tea, while the contents of tanin and caffeine were lower than those of Sri-Lanka's Products. The quantities of mineral in Sri-Lanka's products were determined as 300ppm P, 15,000ppm K, 1,400ppm Mg, 4,000ppm Ca, 22ppm Cu, 21ppm Cr and 45ppm Zn. These contents were higher than those of domestic products. Al content was 4,100ppm in domestic products. Pb and Cd were not detected in two kinds of black tea products. In Sri-Lanka's black tea, 8 kinds of organic acids were identified and the major organic acids were shikimic, citric and quinic acid, while 6 kinds of organic acids were identified in domestic products and were quinic and gallic acid, as the major organic acids. The content of sucrose was higher than that of Sri-Lanka's product and theaflavin, thearubigin and theobromine were abundant, as compared with those in domestic products.

• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.3
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• pp.413-417
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• 2003

To evaluate the antimicrobial activity of green tea against putrefactive microorganism in steamed bread, antibacterial activity of green tea extract against well-known strains of spoilage bacteria (Bacillus subtilis ATCC 6633, Bacillus pulmilus KCTC 3348 and Bacillus cereus IFO 12113) and mold (Aspergillus niger KCCM l1239) in bread was determined using the paper disk method. The green tea extract (GTE) showed the inhibition effects on the growth of all the strains of bacteria and mold at 1, 2, 3% levels. The activity of GTE was stable in the wide range of pH (4~9) and temperature (50~20$0^{\circ}C$). When green tea powder (GTP: 1, 3, 5%) was added to steamed bread increase of total bacterial and mold counts declined during storage at 25"C as the levels of GTP increased. By addition of 5% GTP, mold appeared 1 day late extending shelf life of steamed bread compared to control bread without GTP. Therefore, the levels of GTP added to steamed bread could be more than 5% for extended shelf life and wholesomeness of steamed bread.read.

• Preventive Nutrition and Food Science
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• v.5 no.4
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• pp.189-193
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• 2000

Preservative and antimutagenic effects of green tea leaves added Chinese cabbage kimchi (GK1, GK2, GK3, and GK4 : 1, 2, 3 and 4 of green tea leaves (GTL) in proportion of 100 of salted Chinese cabbage were added to kimchi) were compared to those of the Chinese cabbage kimchi without GTL (control kimchi, CK). Fermentation period of GKs was further delayed than that of CK. The initial pH and acidity between GKs an CK were similar, but the time reach optimally ripened status of kimchi (pH 4.3) was different. CK took 6 days, while GK1, GK2, GK3 and GK4 took 6, 10, 12 and 14 days at 10℃, respectively. The growth of Leuconostoc sp. and Lactobacilus sp. in GKs delayed comparing to those in FCK. Among GKs, as the added amount of green tea leaves increased, the growth of lactic acid bacteria was retarded. The antimutagenic effects of juices from GKs and CK were studied against aflatoxin B₁(AFB₁) in the Ames test on Salmonella typehimurium TA100 and N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) in the SOS chromotest using E. coli PQ37. Juices from optimally ripened GKs (pH 4.3) showed 52∼76% inhibition rates against the indirect mutagen, aflatoxin B₁ induced mutagenicity while 49% inhibition rate by CK in the Ames test. Juices from GKs and CK showed 44∼67% and 36% inhibition rate against direct mutagen, MNNG (70 ng/assay) induce mutagenicity in the SOS chromotest. Thus GKs delayed fermentation period of kimchi and exhibited higher antimutagenic activity than CK.

• Journal of Life Science
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• v.6 no.1
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• pp.56-65
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• 1996

Black tea extractbsupplemented with 10% sucrose was fermented by fungus at 30$\circ$C. A pellicle thick as 7$\sim$8 mm covered entire surface of the medium and the wxtract converted to acidic beverage(abbreviated below as fermented black tea) by 14 days of fermentation. It was a kind of acetic acid fermentation depending on symbiotic microorganisms. During the fermentation strains of yeasts(Saccharomyces cerevisiae and Eeniella sp.)and bacteria(Bacillus subtilis, Kurthia zopfii, Gluconobacter oxydans and Deinicoccus sp.) were isolated from aqueous layer. Contrastly to it, a bacterial strain(Acetobacter aceti) was isolated from thick pellicle. The bacteria grew as a viscouse cluster on solid agar medium differently from usual strains of A. aceti. Fermented black tea had sweet-sour taste and sweet smell.

• Journal of the Korean Society of Food Science and Nutrition
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• v.28 no.5
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• pp.1064-1068
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• 1999

This study was quality changes of sulgiduk added green tea powder during storage. Sulgiduk prepared with various concentrations of green tea powder; 0%(control group), 0.5%(GT 0.5 group), 1%(GT 1.0 group), 1.5%(GT 1.5 group), 2%(GT 2.0 group), and the changes of its quality during 7 days of storage were investigated. Total microbe numbers, the acidity and pH in sulgiduk during storage were decreased with increasing the added amounts of a green tea powder, and especially those of GT 1.0 and GT 1.5 groups had relatively the lower than other groups. The "L" value(lightness) of the control group was the highest among five groups, and its value was decreased throughout storage, and especially GT 0.5 groups had the lowest brightness. The "a" value(reddness) of the control group was higher than other four groups, and increased GT 2.0>GT 1.5>GT 1.0>GT 0.5 groups, in that order. The "b" value(yel lowness) was increased in the order; GT 2.0>GT 1.5>GT 1.0>GT 0.5 groups. These results indicated that GT 1.0 group showed the best quality than other groups of sulgiduk during storage. of sulgiduk during storage.

• Journal of the Korean Society of Food Science and Nutrition
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• v.35 no.9
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• pp.1185-1193
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• 2006

This study investigated the effects of green tea on the disorders of lipid metabolism, oxidative system and hepatic functions induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), using adult male rats (SD) for 3 weeks. These 36 animals were divided into four groups. TCDD ($50{\mu}g/kg$ BW) was intraperitoneally injected at the beginning of experiment. Green tea powder was added 1% or 3% levels in basal diets respectively. Relative weights of thymus were decreased about one-third of control group, but those of liver, brain and testis were significantly increased in rats treated TCDD. Neutrophill% and lymphocyte% by TCDD treatment was improved by green tea diets. In liver functional enzyme, elevation of glutamic oxaloacetic transaminase (GOT) and alkaline phosphatase (ALP) activities due to TCDD treatment was lowered by green tea diets. The concentrations of serum and liver lipids were significantly increased by TCDD treatment, however, those of serum and liver triglyceride tended to decrease by green tea diets. Fecal lipid excretion was increased in rats fed green tea diets. Especially, fecal total cholesterol level was significantly elevated by 3% green tea diets. The activities of superoxide dismutase (SOD) were increased in rats fed 3% green tea diets. Increment of benzphetamine N-demethylase (BPND) activity by TCDD treatment was declined by 1% green tea diets. These results indicate that green tea can exert improving effects on liver lipid accumulation and unfavorable hepatic functions, and elevate antioxidation.

• Korean Journal of Soil Science and Fertilizer
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• v.33 no.3
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• pp.160-166
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• 2000

The reasonable level of nitrogen fertilizer of Gyokuro tea which is producted fresh leaves plucked from shade tea plants is a key factor to increase crop yield and quality. Nitrogen were applied at the level to 60, 80, 100 and $120kg\;10a^{-1}$. Analytical results of yield and quality of Gyokuro tea are summarized as follows : The soil fertility of experimental field was higher in organic matter($59.8g\;kg^{-1}$) and available phosphate($1,285mg\;kg^{-1}$), but lower in pH(4.79) compared to the common field. As the amount of nitrogen fertilizer application was increased to $80kg\;10a^{-1}$, the yield of tea leaves, the content of total nitrogen, total amino acid, caffeine and chlorophyll were increased. However, the yield of tea leaves was not increased above $100kg\;10a^{-1}$ and the increased level of nitrogen fertilizer did not show any different in the content of tannin and vitamin C. When the amount of nitrogen fertilizer application was raised, the content of thiamine and arginine increased, but the content of aspartic acid, serine and glutamic acid decreased. The content of fatty acid was produced $2.850{\sim}3.012mg\;100g^{-1}$ Especially, the content of oleic acid, linoleic acid and linolenic acid was higher at the level of $80kg\;10a^{-1}$ application than other treatments. As nitrogen was applied at $80kg\;10a^{-1}$, sensory score was 0.2~4.6 point higher than other treatments. Consequently, $80kg\;10a^{-1}$ is considered to be the best level of nitrogen fertilizer both quality and crop yield.

• Food Science and Preservation
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• v.9 no.4
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• pp.400-405
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• 2002

Herbs are widely used as a source of tea and otherwise such as botanical medicine, essential oil for perfumes, cosmetics, and food spices. This study was carried out to investigate the characteristics of herb tea prepared with lavender, rosemary, mint, thyme and sage cultivated in korea. Approximate composition were as follows : crude protein 1.4∼17.5%, crude fat 6.1∼15.8%, sugars 43.5∼61s%, crude ash 7.7∼10.7%. Minerals contents of Ca ranged 707∼1763mg%, P 234 ∼513mg%, K 2,391∼3,430mg%, and Mg 361∼573mg%. Vitamins were $\beta$ -Carotene 6.9∼27.7mg%, B$_1$, 0.34∼0.62mg%, B$_2$1.37 ∼2.52mg%, niacin 5.3∼8.8mg%, and C 102∼111mg%. The changes of chromaticity a and b, pH, and sugar content of the herb tea at the different temperatures were decreased 80$\^{C}$ and 100$\^{C}$ in comparison to 60$\^{C}$ but increased chromaticity L. In the result of sensory test of the processed herb tea was more preferred than the market goods.

• Current Research on Agriculture and Life Sciences
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• v.31 no.2
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• pp.101-107
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• 2013

This study was undertaken to determine free radical scavenging capacity and oxidative DNA damage protecting activity of methanol extract of red tea stem. The extract was subjected to assess their antioxidant potential using various in vitro systems such as $DPPH^{\bullet}$, $ABTS^{{\bullet}+}$, super oxide and nitric oxide free radicals and it exhibited $IC_{50}$ values of $68.88{\pm}1.1$, $12.08{\pm}0.65$, $404.38{\pm}1.6$, $93.6{\pm}2.7{\mu}g/mL$ respectively. Red tea extract also showed ferric reducing ability (FRAP) with 2606.85 mmol Fe (II)/g of extract. Furthermore, Methanol extract of red tea stem showed significant DNA damage protecting activity in concentration dependent manner against $H_2O_2+UV$ induced photolysis on pUC19 plasmid DNA. Results of this study showed that the methanol extract of Red Tea stem has strong antioxidant potential along oxidative DNA damage protecting capacity that would be the significant sources of natural antioxidants, which might be helpful in preventing the progress of various oxidative stress generated diseases. Further study is necessary for isolation and characterization of the active antioxidants, which may serve as a potential source of natural antioxidant.

• The Korean Journal of Food And Nutrition
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• v.7 no.4
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• pp.253-258
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• 1994

This thesis is to analyze the ingredients of five-fruit tea depending on extraction time as a basic experiment for quality improvement and industrialization of traditional Korean beverage. According to extraction time, the acidity of the tea is 2.4% at 30 minutes, 2.3% at 50 minutes and 1.7% at 70 minutes, and soluble solid is 0.22 g, 0.31 g and 0.41 g. The pH of five-fruit tea, which is 4.70, 4.85 and 4.98 at each time, and total sugar is 54.01 m9, 108.82 m9 and 142.92 mg as extraction time increases. The total amount of free sugars is 1.14 mg, 1.36 mg and 2.17 mg, and glucose, surcose and fructose which are 98.2%, 92.6% and 92.6% of the whole percentage occupy the most part of free sugars. The total free amino acids content increases to 84.94 mg, 99.67 mg and 120.40 mg. The five kinds of amino acids like serine, glutamic acid, threonine, proline and alanine amount to 94.5%, 93.6% and 94.7% at all. she variation in the percentage of free amino acids content in accordance with extraction time is as follows : threonine, extracted for 50 minutes, is reduced considerably and glutamic acid decreases gradually as extraction time increases. When proline is extracted for 50 minutes, it's rate of increase Is most high.