• Journal of the Korean Home Economics Association
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• v.17 no.2
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• pp.32-38
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• 1979

The purpose of this experiment was to find out the contained quantity of ascorbic acid form persimmon tea. They were different according to the month when the persimmon leaves were picked, the way of cooking and the length of time spent after cooking. The results of experiment can be summarized as follows : 1. About the same contained quantities of ascorbic acid were obtained among the persimmon leaves picked in September and October, and small contained quatities of it were obtained among the persimmon leaves picked in November. Therefore it can be concluded that the persimmon leaves picked in September and October are better than the leaves picked in November for permision tea. 2. According to the way of cooking the contained quantity of ascorbic acid were different. When green leaves were washed and boiled for 1 monute and dried in the shade for 48 hours, the largest contained quantity of ascorbic acid were obtained. When they were steamed in the steam box for 1 minute and 30 seconds and dried in shade for 48 hours medium contained quantity of ascorbic acid were obtained . The contained quantity of ascorbic acid were decreased when green leaves were dried without boiling when green leaves were dried without boiling or when branches of leaves were taken away by hand and dried. 3. The contained quantity of ascobic acid were also different according to the length of time spent after cooking. After 15 minutes from cooking it began to increase and after 150 minutes it reached the highest degree. After this time it began to decrease. 4. the best fragrance, taste and color of the Persimmn Tea are found out, after steaming in the steaming box for one minute and half second and after drying in the shade for fourty-eight hours.

• Preventive Nutrition and Food Science
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• v.12 no.1
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• pp.35-39
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• 2007

This study was conducted to investigate the effects of soil selenium (Se) supplementation level on Se contents of green tea and milk vetch. Four different concentrations of sodium selenite ($Na_2SeO_3$) solutions (0.0, 3.3, 33.0 and 165.0${\mu}g/mL$) were prepared and one liter of each solution was well mixed with 10 kg of compost (cowpea soil) to give four different levels of Se-containing soil: $T_1$, 0; $T_2$, 33; $T_3$, 330; $T_4$, and 1,650${\mu}g$/100 g soil. Green tea plants and milk vetch were individually cultivated in those soils for 60 days. Se contents of freeze-dried green tea leaves were 6.87, 10.40, 12.04, and 20.19 ${\mu}g/g$, respectively; all of which were significantly different (p<0.05) from the others except for $T_2$ and $T_3$. The results showed that Se-contents of green tea leaves were increased 1.5$\sim$2.9 times as the Se level in the soil increased. Regression equation between Se contents in green tea (Y) and soil Se supplementation level (X) was: Y=0.007X＋8.857. However, Se contents in the milk vetch were increased significantly (p<0.05) more with the same treatments $T_3$ (74 ${\mu}g/g$) and $T_4$ (187$\mu$g/g) in comparison to those at $T_1$ (5.0 ${\mu}g/g$) and $T_2$ (12.0$\mu$g/g). The increases ranged from approximately between 2.4 to 37.4 times that of the control group. Regression equation between Se contents in milk vetch (Y) and soil Se supplementation level (X) was: Y=0.1063X＋15.989. The large difference of Se contents between green tea leaves and milk vetch would be attributed by the difference of protein contents between the 30% or higher protein-content of legumes and 15$\sim$20% protein of shrubs. The present study clearly indicates that green tea leaves and milk vetch can be enriched in selenium by supplementing the soil with Se. Therefore, Se-enriched green tea or milk vetch powder could be utilized as functional foods in Se-fortified green tea drinks or salads, or as food additives to enhance the daily intake of Se.

• Bulletin of the Korean Chemical Society
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• v.26 no.5
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• pp.747-754
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• 2005

Liquid chromatographic methods with UV and fluorescence detection have been used to determine the levels of (+)-catechin, (-)-epicatechin, (-)-epicatechin gallate, and (-)-epigallocatechin gallate in Korean green tea infusions. The extracts of Korean green tea leaves or powders in water at various temperatures (100 ${^{\circ}C}$, 80 ${^{\circ}C}$, 60 ${^{\circ}C}$) and time, were washed with chloroform and re-extracted to ethyl acetate. The ethyl acetate phase was dried and re-dissolved in methanol and analyzed. Five catechin compounds were separated by gradient elution. The flavonoids were found decomposed on prolonged extraction, thus exhaustive extraction by a Soxhlet apparatus was found useless for green tea. Some unknown components were found in the extracts at 100 ${^{\circ}C}$. When the green tea was filtered and re-extracted with new fresh water, still some flavonoids were extracted. However, the contents of flavonoids in the third extract were found negligible. The flavonoid extraction rate of green tea powders was higher than that of green tea leaves, but flavonoid decomposition of green tea powders was also faster than that of green tea leaves. The traditional way of drinking green tea was found appropriate in view of flavonoids intake.

• Korean Journal of Soil Science and Fertilizer
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• v.35 no.6
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• pp.381-386
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• 2002

A field experiment was conducted to evaluate the effect of split-application of slow-release fertilizer on the tea plant. The yield of the 1st harvested tea leaves had increased 12% in the slow-release fertilizer(two time split manuring) compared with the traditional manuring(four time split manuring), but that of the slow-release fertilizer to one time split manuring had decreased $6{\pm}3%$. In case of the 1st harvested leave, the contents of chemical components related to quality such as total nitrogen, total amino acid, chlorophyll, vitamin C and theanine were somewhat higher in the leaves of slow-release fertilizer(two time split manuring) treatment than in the traditional manuring, but that of tannin was low. The one time split manuring of slow-release fertilizer had a contrary tendency with two time split manuring treatment. In scoring test, appearance and quality of green tea were more excellent in the two time split manuring compared with one time split manuring of slow-release fertilizer and with the traditional manuring (four time split manuring). Therefore, use of slow-release fertilizer increased yield and quality of tea leaves, and decreased loss of nitrogen, phosphate and potassium.

• Journal of the Korean Society of Food Culture
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• v.5 no.2
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• pp.229-233
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• 1990

Changes in chemical components of green tea leaves at different cooking conditions-blanching and frying-were surveyed as a method of utilizing low graded green tea leaves which missed appropriate plucking times. There was no significant difference in protein content during cooking. But contents of chlorophyll, tannin, vitamin C and caffeine were decreased during cooking, contents of chlorophyll and caffeine showed a greater decrease in frying than blanching. Content of total amino acid of green tea leaf was 15.8% and blanching showed bigger diminution of its content in comparision with frying during cooking.

• Food Science and Preservation
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• v.7 no.1
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• pp.99-102
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• 2000

Comparing and analysing the productivity and the main ingredients of persimmon leaves by cultivars were conducted to improve the quality and productivity of the per-simmon leaf tea. As a result of the survey, Dungsi was decidedly good in growth co-ndition of survival rate, stem diameter and the number of shoots etc. Also , DUngsi had the highest leaf productivity of 567 leaves and the leaf weight of 1.98 kg per one plant after three years of planting . On accounts of productivity, ingredient analysis and panel test etc. we collectively through that Dungsi was the best cutltivar for the persimmon leaf tea.

• Nutrition Research and Practice
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• v.6 no.2
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• pp.106-112
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• 2012

This study was conducted to investigate the effects of $Sasa$ $quelpaertensis$ bamboo and green tea on plasma and liver lipids, platelet aggregation, and erythrocyte membrane Na channels in ovariectomized (OVX) rats. Thirty female rats were OVX, and ten female rats were sham-operated at the age of 6 weeks. The rats were divided into four groups at the age of 10 weeks and fed the experiment diets: sham-control, OVX-control, OVX-bamboo leaves (10%), or OVX-green tea leaves (10%) for four weeks. Final body weight increased significantly in the OVX groups compared with that in the sham-control, whereas body weight in the OVX-green tea group decreased significantly compared with that in the OVX-control ($P$ < 0.01). High density lipoprotein (HDL)-cholesterol level decreased in all OVX groups compared with that in the sham-control rats ($P$ < 0.05) but without a difference in plasma total cholesterol. Plasma triglycerides in the OVX-green tea group were significantly lower than those in the sham-control or OVX-control group ($P$ < 0.05). Liver triglycerides increased significantly in the OVX-control compared with those in the sham-control ($P$ < 0.01) but decreased significantly in the OVX-green tea group compared with those in the OVX-control or OVX-bamboo group ($P$ < 0.01). Platelet aggregation in both maximum and initial slope tended to be lower in all OVX rats compared with that in the sham-control rats but was not significantly different. Na-K ATPase tended to increase and Na-K cotransport tended to decrease following ovariectomy. Na-K ATPase decreased significantly in the OVX-green tea group compared with that in the OVX-control group ($P$ < 0.01), and Na-K cotransport increased significantly in the OVX-bamboo and OVX-green tea groups compared with that in the OVX-control ($P$ < 0.05). Femoral bone mineral density tended to be lower in OVX rats than that in the sham-control, whereas the green tea and bamboo leaves groups recovered bone density to some extent. The results show that ovariectomy caused an increase in body weight and liver triglycerides, and that green tea was effective for lowering body weight and triglycerides in OVX rats. Ovariectomy induced an increase in Na efflux via Na-K ATPase and a decrease in Na efflux via Na-K cotransport. Furthermore, consumption of green tea and bamboo leaves affected Na efflux channels, controlling electrolyte and body water balance.

• Korean Journal of Food Science and Technology
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• v.40 no.5
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• pp.485-490
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• 2008

In this study, organic tea leaves were characterized with the aim of developing an organic beverage process. The green tea leaves grown using organic farming techniques were collected in Haenam, Korea. Catechins in green tea leaves were extracted by chloroform and ethyl acetate and these were then analyzed quantitatively and qualitatively by HPLC (high pressure liquid chromatography). The color and pH values of the green tea extracts were also measured. The catechin levels of April-harvested, May-harvested and June-harvested, semi-fermented leaves at 0.5% were 66.24, 29.19, 57.11, and 5.27 ${\mu}g/mL$, respectively. Among the detected catechins, the level of (-)-epigallocatechin gallate was the highest while that of (-)-epigallocatechin was not detected. The June-harvested leaves were selected as raw material for development of the green tea beverage, based on the levels of catechins, economic viability and yield of tea extract. As the level of extract increased, the levels of catechins of 0.1, 0.2, 0.5% also increased by 1.5, 11.78 and 41.01 times. From the results of the sensory evaluation of June-harvested leaf-extract, the sensory score of color was the highest in 0.1%, while the flavor and overall quality were the highest in 0.2%.

• Applied Biological Chemistry
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• v.22 no.2
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• pp.97-100
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• 1979

Tea leaves were harvested from the two cultivating sites in May, July and September. Tannin and caffeine, main factors for the quality of tea products, were analyzed and compared with the wild tea leaves and the cultivated. Aroma components of two varieties of tea leaves harvested in September were analyzed by gas-chromatographic method. The results obtained were as follows. 1. Tannin contents were 10-14% same as Chinese tea variety and increased gradually to September and showed no difference between the wild tea leaves and the cultivated. 2. Caffeine contents were 1.5-3% same as other Chinese variety and showed no difference between the wild tea leaves and the cultivated. 3. Aroma components showed nearly similar patterns between two different tea varieties and were identified as phenol, iso-butyl aldehyde, n-butyl aldehyde, iso-valer aldehyde, n-butyl alcohol, iso-amyl alcohol, iso-valeic acid, benzaldehyde, n-valeric acid and linalool among 32 peaks.

• Applied Biological Chemistry
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• v.49 no.2
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• pp.163-164
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• 2006