• 한국식품조리과학회지
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• 제15권2호
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• pp.95-101
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• 1999

This study was carried out to prepare green teas by traditional roasting manufacturing process, Ku Geung Ku Po and to determine the quality charateristics of the green teas by examining the change of their main components induced during this roasting process. The content of total sugars in unroasted tea leaves was 7.82%. Its content of roasted teas was decreased by increasing the number of roasting and there was significantly differences between samples. The content of total sugars in 9th roasted green tea was 3.98%. The total nitrogen contents of green teas produced by this process were 4.96∼6.38%. The more the number of roasting and the less content of tannin in green teas. And the ratio of total nitrogen and tannin in tea leaves 21.97 but its ratio in 9th roasted tea was increased to 45.54. The ascorbic acid in tea leaves consisted in 1,820.3 mg/100g but its content was decreased by increasing the number of roasting process. Whereas the content of caffeine in green teas was not reduced significantly by this traditional method. Of all amino acids, green tea produced by Ku Jeung Ku Po was rich glutamic acid, lysine and aspartic acid. And especially, phenylalanine, which was rarely found in other green teas, was abundant in these green teas. The compositions of glutamic acid and methionine were increased as increasing the number of roasting process but those of aspartic acid and arginine decreased by these processing. The main fatty acids of Ku Jeung Ku Po green tea were linolenic acid, linoleic acid and palmitic acid and the contents of unsaturated fatty acid in green teas were composed over 70% of total fatty acid. And the fatty acid contents in green teas were not affected during Ku Jeung Ku Po's process. The contents of minerals in these teas was rich in the oder of potassuim. magnessuim and calciumim, and these contents were not observed the prominant change during the process.

• 동아시아식생활학회지
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• 제14권2호
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• pp.156-160
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• 2004

This study was carried out to examine the changes of chlorophyll a and b contents by the extraction temperatures and the number of soaking using five kinds of Korean green teas(3 kinds of green tea and 2 kinds of tea bag) which were obtained from a local market in Daegu city, Korea. The chlorophylls were extracted with 80% acetone, and determined by a visible spectrophotometer. The concentration of chlorophyll in Sulrok(tea bag) were the highest among all kinds of teas when they were extracted at 60, and decreased with the number of soaking increased. On the other hand, the chlorophyll content of green teas was the highest at 80, and decreased with the increase of the number of soaking as the tea bag did. It was found that the Korean tea bag contained more chlorophyll than green teas did, and green teas contained significantly more chlorophyll b than chlorophyll a.

• 한국식품과학회지
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• 제54권2호
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• pp.228-234
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• 2022

Various types of tea have been cultivated to obtain different flavors and enhance their functional properties. The objective of this study was to investigate the physicochemical properties of γ-aminobutyric acid (GABA) teas produced from commercial Korean green, white, and black teas. The concentration of total minerals was reduced in GABA green tea and GABA white tea but was improved in GABA black tea. The essential, non-essential, and total free amino acid contents were remarkably increased in the GABA teas. The amino acid GABA content was increased by 561.00 and 294.20 times in GABA white tea and GABA black tea, respectively. The antioxidant potential was not reduced, although the total polyphenol and total flavonoid contents decreased in GABA green tea and GABA black tea. The results indicated that the overall nutritional value of commercial green, white, and black teas could be improved by processing them into GABA teas.

• 원예과학기술지
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• 제30권5호
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• pp.519-526
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• 2012

혐기처리 녹차를 알루미늄 포장에 보관하여 상온, $4^{\circ}C$, $-10^{\circ}C$에 저장 시 품질관련 화학성분인 총질소, 총아미노산, 탄닌, 카페인, 엽록소, 비타민 C 및 지방산은 저장기간이 길어질수록 함량이 감소되었다. 각 성분의 함량 감소폭은 $-10^{\circ}C$ 저장이 상온, $4^{\circ}C$에 비해 적었으며, 함량 감소는 상온에 비해 8개월, $4^{\circ}C$에 비해서는 4개월 정도 지연되었다. 저장 시녹색을 나타내는 'a'값이 감소할수록 품질이 저하되는데, 혐기처리 녹차의 표면 녹색을 나타내는 'a'값은 12개월 저장 시 상온 > $4^{\circ}C$ > $-10^{\circ}C$ 순으로 저장온도가 높을수록 녹색이 감소됨을 알 수 있었다. 형상, 향, 맛 등으로 평가하는 관능평가는 100점 만점에 점수가 낮을수록 품질이 저하되며, 저장온도에 따라 혐기처리 녹차의 품질이 상이하였는데 $-10^{\circ}C$ 12개월 저장 시 80점, $4^{\circ}C$ 8개월 81.1점, 상온 4개월 80.4점으로 저장온도가 낮을수록 품질이 양호하였다. 따라서 본 연구의 내용을 종합한 결과, $-10^{\circ}C$를 혐기처리 녹차의 가장 효과적인 저장온도로 제시하고자 한다.

• 생명과학회지
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• 제5권2호
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• pp.20-20
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• 1995

The aroma components of commercial green teas picked inAugust were collected and identified. The extract of aroma compounds in green tea were accoimplished by a modified rotary evaporation. The concentrated wxtracts were analyzed and identified by GC and GC-MS. In GC analysis, T$_{R}$ value of GC represented bt KI value which standardized. The most abundant components of green teas picked in August were 1-Penten-3-ol, trans, trans-2, 4-heptadienal, linalool, $\beta$-ionone and nerolidol.

• 생명과학회지
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• 제5권2호
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• pp.76-80
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• 1995

The aroma components of commercial green teas picked inAugust were collected and identified. The extract of aroma compounds in green tea were accoimplished by a modified rotary evaporation. The concentrated wxtracts were analyzed and identified by GC and GC-MS. In GC analysis, T$_{R}$ value of GC represented bt KI value which standardized. The most abundant components of green teas picked in August were 1-Penten-3-ol, trans, trans-2, 4-heptadienal, linalool, $\beta$-ionone and nerolidol.

• Preventive Nutrition and Food Science
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• 제9권3호
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• pp.222-226
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• 2004

Hydrocarbons induced by gamma-irradiation of green, black, and oolong teas were analyzed to determine whether the hydrocarbons can be used as markers for detecting post-irradiation of these teas. The samples were irradiated at 0, 2.5, 5, 7.5, and 10 kGy. Detection was attempted by extracting fat from the teas, separation of hydrocarbons with florisil column chromatography, and identification of hydrocarbons by gas chromatography-mass spectroscopy (GC-MS). Concentration of hydrocarbons increased with the irradiation dose. The major hydrocarbons in irradiated green, black, and oolong teas were 1-tetradecence (14:1), pentadecane (15:0), 1,7-hexadecadiene (16:2), 1-hexadecene (16:1), 8-heptadecene (17:1), and heptadecane (17:0). Radiation-induced hydrocarbons in teas were 1,7-hexadecadiene and 8-heptadecene. These compounds were not detected in non-irradiated samples, so the hydrocarbons (16:2, 17:1) can be used as markers for detecting post-irradiation of the teas. Furthermore, detection of hydrocarbons after 12 months storage at room temperature remains a suitable method for identifying irradiated teas.

• 한국식품과학회지
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• 제43권4호
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• pp.407-412
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• 2011

본 연구에서는 녹차와 녹차에 미생물을 접종하여 발효시킨 후 발효차의 유리형 및 결합형 향기성분을 headspace-solid phase microextraction(HS-SPME)-GC/GC-MS를 이용하여 분석하였다. 녹차가 미생물학적 발효과정을 거치는 중에 녹차에 존재하는 aldehyde류와 ketone류는 감소하였고 linalool과 geraniol은 증가하였다. 녹차와 후발효차 잎에 추가적으로 효소를 처리하여 분석한 결과 녹차에서는 (Z)-3-hexen-1-ol>benzaldehyde>3-hexenyl acetate>geraniol순으로 향기성분이 증가되었고, 후발효차에서는 (Z)-3-hexen-1-ol>benzaldehyde>geraniol>3-hexenyl acetate>1-hexanol 순으로 증가하였으며, 녹차보다는 후발효차에서 효소에 의해 증가되는 향기성분이 많았다. 효소양을 달리하여 처리하였을 때 녹차와 후발효차 모두 효소의 양이 증가함에 따라 휘발성 향기성분이 증가하는 양상을 보였다. 본 실험을 통하여 효소처리를 통해 녹차와 후발효차의 향기를 증가시킴으로써 녹차와 후발효차의 향기 품질을 향상시킬 수 있는 가능성을 확인할 수 있었다.

• 한국약용작물학회지
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• 제14권6호
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• pp.322-328
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• 2006

Green tea is of particular source as it has been found to have strong antioxidant activities. The extracts of green tea during the commercial harvest seasons from April, 2003 to August, 2003 were compared. The purpose of this study was to determine the correlation between the polyphenol content of green teas and its antioxidant activities. The con-tent of total polyphenols was analyzed and several antioxidant testings were performed. The levels of total polyphenols were higher in the green teas (e.g. Woojeon, Sejak) harvested during very early spring and lower in the green teas harvested late(eg. Ipha, Yepcha). In particular, the free radical scavenging, the inhibition of LDL oxidation, the cytoprotective effect and the inhibition of DNA damage were correlated with the total polyphenol contents of green tea extracts harvested early spring such as Woojeon, Sejak and Jungjak. The results obtained here show that all extracts of green teas including purified green tea catechin, GTC, have strong antioxidant activities on oxidative stress in vifrθ. The variation in polyphenol content and antioxidant activities among various types of green tea by the harvesting time may provide critical information for investigators and consumers using tea in purposes of nutrition and chemoprevention.

• 대한화학회지
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• 제63권2호
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• pp.78-84
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• 2019

High-resolution $^1H$ NMR spectroscopic technique has been widely used as one of the most powerful analytical tools in food chemistry as well as to define molecular structure. The $^1H$ NMR spectra-based metabolomics has focused on classification and chemometric analysis of complex mixtures. The principal component analysis (PCA), an unsupervised clustering method and used to reduce the dimensionality of multivariate data, facilitates direct peak quantitation and pattern recognition. Using a combination of these techniques, the various green teas and black teas brewed were investigated via metabolite profiling. These teas were characterized based on the leaf size and country of cultivation, respectively.