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쌍끌이 중층트롤어법의 연구 ( 2 ) - 모형어구의 깊이에 관하여 - ( A Study on the Pair Midwater Trawling ( 2 ) - Working Depth of the Model Net - )

  • 이병기
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.31 no.1
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    • pp.45-53
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    • 1995
  • Working depth of the model net was determined by using of the same experimental tank and the same model net that used in the forwarded report in a series studies. The depth of the net which indicates the depth of the head rope from the water surface, was determined by the photographs taken in front of the net mouth with the combination of towing velocity, warp length and distance between paired boats. The results obtained can be summarized as follows: 1. Working depth of model nets A and B was varied in the range of 0.09~1.66$m$,and 0.04~1.34$m$(which can be converted into 2.7~40.2$m$and 1.2~49.8$m$in the full-scale net) respectively, and the depth of model net A was slightly deeper than the depth of the model net B. 2. Working depth ($D$,which is appendixed m for the model net, f for the full-scale net, A and B for the types of the model nets) can be expressed as the function of towing velocity$V_t$, as in the model net($V_t$=$m$/$sec$) $D_{mA}$=(-1.99+0.65$L_w$) $e^{-1.72V_t}$ $D_{mA]$=(-1.91+1.04 $L_w$) $e^{2.88V_t}$ in the full-scale net($V_t$=$k$'$t$ $D_{fA}$=(-29.32+0.65$L_w$)$e^{0.40 V_t}$ $D_{fB}$=(-57.60+1.04$L_w$)$e^{-0.67 V_t}$ 3. Working depth 9$D$ appendixes are as same as the former) can be expressed as the function of warp length$L_w$) in the model net, and can be converted into full-scale net as in the model net ($V_t$=$m$/$sec$) $D_{mA}$=-0.99 $e^{-1.42V_t}$+0.67$e^{-1359V_t}$$L_w$ $D_{mB}$=-.258$e^{-3.77V_t}$+1.16$e^{-3.15V_t$ $L^w$, in the full-scale net($V_t$=k't) $D_{fA}$=-29.28$e^{-0.32V_t}$+0.67$e^{-0.37V_t$$L_w$ $D_{fB}$=-69.10$e^{-0.81V_t}$+1.16$e^{-0.72V_t}$$L_w$. 4. Working depth was gradually shallowed according to the increase of the distance between paired boats.

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Korean Tea Therapy in "The Annals of the Joseon Dynasty" ("조선왕조실록"을 통해 본 한국의 차문화)

  • Lee, Sangjae;Jung, Jihun
    • Journal of Society of Preventive Korean Medicine
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    • v.17 no.2
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    • pp.17-28
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    • 2013
  • According to "The Annals of the Joseon Dynasty", we know that korean ancestors confuse tea prescription with green tea. It makes cultural misunderstanding Tea doesn't mean green tea but tea prescription. It is caused that tea prescription has been called tea habitually in Korea. Korean don't drink green tea much. Instead, they have had a habit of drinking decoction of medicinal herbs and they called it tea. This habit has developed into Korean traditional tea culture. In the palace in the Joseon Dynasty period, Ginseng tea was used in the tea ceremony. When the king had poor health or had a disease or was even on the eve of death, a royal physician tried to cure him by tea. They used about 30 kinds of tea according to "The Annals of the Joseon Dynasty" Such as ginseng tea, astragalus tea, ginger tea. Tea in korea is not a drink but the way to cure a disease. Korean people usually get to drink decoction of other herbs instead of green tea. This became the basis of korean traditional tea culture. We need to change a definition of Korean tea like this way and study about it much more. With this research paper, korean tea culture should be studied on more various ways and established itself as original and unique tea culture. On the basis of this studies, Korean tea brand can be famous in the world like Chinese tea or Japanese tea.

A Study on the Interchange of Korean and Chinese Tea Culture (한중차문화교류고)

  • 김명배
    • Journal of the East Asian Society of Dietary Life
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    • v.3 no.2
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    • pp.15-24
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    • 1993
  • (1) According to the history of three kingdoms, tea was introduced to Korea at the period of Korea at the period of Sun-Duck Queen of Shilla dynasty, and Dae-Ryeom Kim, the emissary, brought tea seeds from Tang China in 828, and sowed them on Mt. Jiri by the order of the King Heung-Duck, Shila. In 1885, The Chosun government took action in transplant 6000 each of tea of tea seeding from Ch'ing. (2) Transmission of schools As for the type of tea through the history of Korea, it could be characterized as cake-tea in the three kingdoms period, lump-tea in Koryo dynasty and leaf-tea in Chosun dynasty. Those were affected by Chinese tea culture. (3) Transfer of tea and tea utensils Kokuryo and Shilla had to import cake-tea from tang China, and Koryo had to import lump-tea from Sung China, and Chosun had to import leaf-tea from ch'ing China. On the other hand, to export various tea to Khitai, Chin, Yuan, and Chosun had to export tea Ch'ing China. And the tea bowl produced in the Sung such as Chien Chou ware and Chi Chou ware, was also introduced to Koryo. (4) Suggestion for the promation of tea industry The Chosun government were adviced to the exchange of Chosun tea for Chosun tea for China horse, by yang Ho, General to the Ming expeditionary forces in Chosun, and were advised to engage in foreign tea trade, by Lee Hong Jyand, minister of commerce for the nothern sea to the Ching.

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Effect of Some Tea on Removability of Cd and Pb Ion in Solution (찻물에서의 Cd과 Pb이온 제거에 관한 차입자의 효과)

  • 김중만;백승화;박성수
    • The Korean Journal of Food And Nutrition
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    • v.11 no.5
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    • pp.521-527
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    • 1998
  • Removabilities of heavy metals(Cd and Pb) by the tea materials (barley-tea, corn-tea, jasmin-tea, brown rice-green tea, black-tea, cassia tora-tea, persimmon peel-tea, and rice-tea) in the tea-water were studied in the various conditions ; particle size of tea (20, 40, 70 mesh), concentration of heavy metal (25, 50, 100 ppm) and extraction temperature(20, 30, 50, 100$^{\circ}C$). The removabilities by the tea solids were increased as the particle size decreased, concentration of heavy metal increased, and extracting temperature increased. Of the nine kinds of tea, Cd and Pb removability by jasmin-tea was highest. In addition, heavy metal removability by cassia tora tea was better than that of other tea as extraction temperature was increased.

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A Study on Change in Chemical Composition of Green Tea, White Tea, Yellow Tea, Oolong Tea and Black Tea with Different Extraction Conditions (녹차, 백차, 황차, 우롱차 및 홍차의 추출조건에 따른 이화학적 성분 조성 변화 연구)

  • Lee, Young-Sang;Jung, Seul-A;Kim, Jung-Hwan;Cho, Kyoung-Sook;Shin, Eul-Ki;Lee, Hee-Young;Ryu, Hye-Kyung;Ahn, Hyun-Ju;Jung, Won-Il;Hong, Sung-Hak
    • The Korean Journal of Food And Nutrition
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    • v.28 no.5
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    • pp.766-773
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    • 2015
  • This study analyzes the chemical composition of green tea, white tea, yellow tea, oolong tea and black tea with respect to extraction temperature and time. The optimum extraction conditions for these teas were determined by assessing the chemical composition of tea brewed at different temperature (50, 60, 70, $80^{\circ}C$) and extraction times (1, 3, 5, 10 minute). Catechins contents were the largest at 5 minutes and generally declined by 10 minutes. Green tea catechins contents were highest when brewed at $70^{\circ}C$ and besides other teas a change of the trend variation at 70 and $80^{\circ}C$. These temperatures did not extract theaflavins in green tea. Extract temperature and time did not significantly affect theaflavins content of white tea, yellow tea, and oolong tea. Black tea, however, was noticeably dependent on extract conditions, which were most effective at $70^{\circ}C$, brewed for 5 minutes. Caffeine content of green tea, yellow tea, and oolong tea was highest at 5 minutes, but temperature did not appear to affect the content. White tea and black tea caffeine content was highest when brewed at $70^{\circ}C$ for 5 minutes. Theobromine content of green tea, yellow tea, oolong tea, and black tea did not show major differences between the study times or temperature, though the content in white tea increased with higher temperatures when brewed for 5 minutes. The extraction of phenolic compounds increased until 5 minutes, and showed not further increase at 10 minutes. Antioxidant capacity of green tea, white tea, and yellow tea were maximized at $70^{\circ}C$ for 5 minutes or $80^{\circ}C$ for 3 minutes, while oolong and black tea were reached maximum antioxidants at $70^{\circ}C$ for 5 minutes. In general, to optimize the beneficial chemical content of brewed tea, a water temperature of $70^{\circ}C$ for 5 minutes is recommended.

Antimicrobial Effect of Tea Extracts from Green Tea, Oolong Tea and Black Tea (녹차, 오룡차 및 홍차 추출물의 항균효과)

  • 김선봉;여생규;안철우;김인수;박영범;박영호
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.24 no.2
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    • pp.293-298
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    • 1995
  • Antimicrobial effect of tea extracts from green tea(steamed, roasted), oolong tea and black tea was investigated. Minimal inhibitory concentration(MIC) of tea extraxcts against 9 well known strains of foodborne pathogenic bacteria such as the Gram positive and Gram negative bacteria was determined at 37$^{\circ}C$. Significant antimicrobial activity was observed in the steamed green tea and the roasted green tea of the water-soluble fraciton, and the steamed green tea of the methanol-soluble fraction, and the steamed green tea, roasted green tea and the oolong tea of the crude catechin fraction. The MIC of these extracts against B. subtillis were 700$\mu\textrm{g}$/ml, 500$\mu\textrm{g}$/ml and 120 $\mu\textrm{g}$/ml, respectively. The crude catechin fraction possessed greater antimicrobial activity than did the other fractions. Among tea extracts, extracts of steamed green tea, roasted green tea and oolong tea showed higher antimicrobial activity than them of black tea. The MIC of the crude catechin fraction obtained from tea extracts against Gram-positive bacteria such as M. Iuteus, B. subtillis and S. mutans were 30~50$\mu\textrm{g}$/ml, 120~240$\mu\textrm{g}$/ml and 120~180$\mu\textrm{g}$/ml, and against Gram-negative bacteri such as e. aerogenes and V. parahaemolyticus were 50~60$\mu\textrm{g}$/ml and 60~70$\mu\textrm{g}$/ml in the broth medium, respectively. Especially, the MIC to Streptococcus mutans which has known as a causative bacteria of a decayed tooth were 120$\mu\textrm{g}$/ml, 140$\mu\textrm{g}$/ml, 180$\mu\textrm{g}$/ml and above 1,000$\mu\textrm{g}$/ml in steamed green tea, roasted green tea, oolong tea and black tea, respectively. Tea extracts had strong growth inhibition activity against foodborne pathogenic and dental bacteria.

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Perception and Attitudes toward Green Tea and Green Tea Cafe Compared by Usage of Green Tea Cafe (녹차전문점 이용유무에 따른 녹차와 녹차전문점에 대한 인식 및 태도)

  • Hong, Hye-Lee;Seo, Sun-Hee
    • Journal of the Korean Society of Food Culture
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    • v.24 no.2
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    • pp.181-190
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    • 2009
  • The purpose of this study was to investigate individuals' perceptions toward green tea and green tea cafes according to their usage of green tea cafes, gender, and marital status. The survey was conducted online and completed by 200 respondents who had been to green tea cafes and by 200 respondents who had not. The visitors of green tea cafes had more positive perceptions regarding the atmosphere, familiar taste, good quality of raw foods, freshness of foods, good service, excellent taste, and menu variety of green tea cafes. Males perceived green tea as 'good for health' more than the females. There was no difference in the perception of green tea cafes by marital status. Regarding a popularization plan for green tea cafes, the customers felt more need for a tea sommelier than the non-customers, and females versus males felt stronger about having a tea sommelier that would provide opportunities to taste various tea products and develop a green tea menu that considered nutrition and health. Unmarried respondents felt a greater necessity for having a place with a comfortable environment, tasting a variety of tea products, and having a chance to experience tea culture. When selecting a green tea cafe, the quality of the food and cleanliness of the cafe were considered to be most important. The implications of the data are discussed.

The Quality Characteristics of Stevia (Stevia rebaudiana Bert) Leaf Tea according to Different Manufacturing Processes (스테비아 잎차의 제조 방법에 따른 품질 특성)

  • Lee, Ung-Soo;Kim, Geun-Sik;Choi, Won-Seok
    • The Korean Journal of Food And Nutrition
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    • v.27 no.2
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    • pp.156-163
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    • 2014
  • In order to develop tea by using the leaves of stevia, which is a herbal plant, and to solve the disadvantages of stevia dried leaf tea, we have manufactured the steamed tea, stir-fried tea and fermented tea by changing the manufacturing processes. As a result of the sensory tests, the steamed tea, stir-fried tea and fermented tea received higher evaluations than the dried leaf tea. In terms of efficiency, it is desired that the total number of steaming and stir-frying is only once, but the fermentation is found to be the most desirable for 2 days. There are no trends for changes in the general ingredients, mineral and free amino acid contents of stevia leaf teas by different manufacturing processes. As a result for the measurement of antioxidant activities, the steamed tea and dried leaf tea did not show significant differences, but the stir-fried tea and the fermented tea show significantly low antioxidant activities as compared to the steamed tea. The contents of stevioside in both the stir-fried tea and the fermented tea were less than that in the dried leaf tea, but in the steamed tea, there was no significant difference in the content of stevioside. Base on the present observations, this study supports high potentials of steaming process in order to produce new stevia leaf tea.

Physiological and Antioxidant Activities of Green, Oolong and Black Tea Extracts (녹차, 오룡차 및 홍차 추출물의 생리활성과 항산화 효과)

  • Kang, Kun-Og
    • Journal of the East Asian Society of Dietary Life
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    • v.21 no.2
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    • pp.243-249
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    • 2011
  • This study investigated the physiological and antioxidant activities of green, oolong, and black tea extracts. The crude catechin extract yields of green, oolong, and black tea were 4.9%, 3.4%, and 2.5%, respectively. Total phenol contents of green, oolong, and black tea were 40.9%, 43.0%, and 38.5%, respectively. The order of the electron donating abilities of green, oolong and black tea were green tea>oolong tea>black tea extracts. The SOD-like activities of green, oolong and black tea extracts at 5,000 ppm were 21.2%, 17.5% and 13.9%, respectively. The nitrite-scavenging abilities of green, oolong and black tea extracts were higher than that of ascorbic acid (p<0.05). Antioxidant activities in soybean oil substrates at 500 ppm were in the order of green tea>oolong tea>black tea${\geq}$BHT (200 ppm). Therefore these results showed that the physiological and antioxidant activities of green tea were better than those of oolong and black tea.

Effects of Temperature, Illumination, and Sodium Ascorbate on Browning of Green Tea Infusion

  • Ye, Qian;Chen, Hao;Zhang, Lin Bin;Ye, Jian Hui;Lu, Jian Liang;Liang, Yue Rong
    • Food Science and Biotechnology
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    • v.18 no.4
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    • pp.932-938
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    • 2009
  • Browning of tea infusion is an obstructive factor influencing shelf life of ready-to-drink green tea. Effects of temperature and illumination on the browning of green tea infusion were investigated. It was shown that both elevated temperature and illumination led to the browning of green tea infusion, but temperature had greater effect on infusion color and level of catechins than illumination. The levels of unoxidized catechins such as (-)-epigallocatechin gallate (EGCg), (-)-epigallocatechin (EGC), (-)-epicatechin gallate (ECg), (-)-epicatechin (EC), and total catechins remaining in the tea infusion were significantly correlated to color parameters of the tea infusion. Sodium ascorbate inhibited the infusion browning by suppressing the oxidation of tea catechins and it is considered to be a more suitable preservative for prolonging shelf life of ready-to-drink green tea than ascorbic acid because it has less effect on tea taste. The effects of temperature and illumination on the epimerization of catechins were also discussed.