• Journal of the Korean Home Economics Association
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• v.44 no.9
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• pp.21-29
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• 2006

The purpose of this study was to investigate the preferences and utilization of green tea and its products for adults living in Chonbuk area. Self-administered questionnaires were collected from 388 (117 male, 271 female) subjects. who were classified into 5 groups by age. Data were analysed by chi-square and ANOVA. The results can be summarized as follows. On the investigation of preferences, there was a significant difference between and among the age groups(p<.001). More than 20% of the subjects in the $20{\sim}29$ years group preferred coffee and juice. A half of the elderly over 60 years preferred a kind of green tea. The frequency of green tea drinking was not significantly influenced by age. Drinking green tea less than once a day was replied by 59.0% of the subject of whom 44.3% drank the green tea at home. and 42.0% got information about green tea from TV or radio. Regarding the satisfaction with products using green tea, 62.6% of the subjects responded only 'mediocre.' The brown rice-green tea was marked to be the highest in terms of recognition among all kinds of products. The green tea-related products were rated higher by the elder group. In conclusion, future research should focus on the development of green tea and its products in accordance with the consumption pattern in each age group.

• Korean Journal of Clinical Pharmacy
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• v.28 no.4
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• pp.342-346
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• 2018

Background: Green tea extracts are approved as nonprescription drug and available as health functional foods, health foods, and beverages. Clinical information on the products is lacking. Methods: Information about the products on green tea nonprescription drugs was obtained from the website of the Korea Pharmaceutical Information Center. The Naver, i.e., a top ranking online search portal, was used for compiling the list of the health functional food products using key words of 'green tea catechin' on August 23, 2018. The recommended daily dosages of catechins were calculated as 30% of the total dried mass of green tea and about 50% of the catechins were considered as epigallocatechin gallate (EGCG). Results: A total of two types of nonprescription drugs containing green tea powder or extracts, nine health functional food products, and three types of health foods were found. The regulatory requirements of the EGCG exceeding 800 mg were reported to be associated with adverse effects of elevated liver enzyme. If consumers take several green tea products concurrently, such as nonprescription drugs with health functional foods or health foods, it could exceed the recommended amount of EGCG. Conclusion: The concurrent use of green tea products as nonprescription drugs, health functional foods, and healthy foods may lead to an increased exposure to EGCG. Pharmacists should be aware the availability of various types of green tea products and the potential risk of liver toxicity due to excessive consumption of EGCG.

• Korean Journal of Poultry Science
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• v.30 no.3
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• pp.183-189
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• 2003

This study was carried out to evaluate effect of dietary green tea by-products (GTB) on laying performance and quality of eggs in hens. A total of 96 laying hens (22-week-old) "Tetran Brown" were allotted to four dietary treatments, which containing 0, 2, 4 and 6% green tea-by products. The results showed that the egg production increased (P＜0.05) in layers fed diets containing 4% or 6% green tea-by products compared to the layers fed control no GTB. Egg weight and egg mass in layers fed diets containing 2% green tea by-products significantly decreased compared to those in the other groups (P<0.05). The feed intake was lower in layers fed diets containing 2% and 6% green tea by-products. The feed conversion ratio was lower (P<0.05) in layers fed diets containing 4% or 6% green tea by-product supplementation respectively. The egg shell thickness was no significantly different between layers fed the control and green tea by-product diets (P>0.05). The egg yolk cholesterol tended to decrease when layers fed diets containing green tea by-products, although the differences were not significant (P＞0.05). The linolenic and docosahexaenoic (DHA) acid contents in egg yolk significantly increased in layers fed diets containing different levels green tea by-products compared to those fed control diet (P<0.05). These results suggest that inclusion of green tea by-products in layer diets is suitable for hens without negative effects on egg composition.

• 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.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.49 no.4
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• pp.295-299
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• 2004

The prices of domestic green tea products are relatively expensive and price differences within products of the same levels of quality are various. Also, there is no basic criteria on evaluation of green tea quality. To group 43 commercial green tea products into several parts by the principal component and cluster analyses, this work was done by use of 8 chemical constituents which were analyzed by NIR system. The principal component and cluster analyses revealed 8 groups. The first group included 16 products that had lower free amino acid and theanine contents. The second group included 5 products having higher free amino acid and theanine contents, but lower ash contents. The third group included 13 products showing medium values of 8 constituents. The IV group included 4 products having higher contents of moisture, free amino acids, and theanine. The V group included 1 product showing higher moisture but lower catechins contents. The VI group included 2 products that had higher moisture and catechins contents, but lower free amino acid and theanine contents. The VII group had higher moisture and catechins contents. The VIII group had higher ash and vitamin C contents. The free amino acid contents which were the most important in flavor evaluation of green tea quality did highly positively correlate with the contents of total nitrogen $(0.956^{**}),\;theanine\;(0.981^{**}),\;and\;caffeine\;(0.793^{**})$, but negatively with the contents of ash $(-0.884^{**})$. The catechins used as for functional ingredients did correlate with contents of caffeine(+) and vitamin C(-), respectively.

• Natural Product Sciences
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• v.19 no.4
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• pp.281-285
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• 2013

This study was designed to investigate the nervous sedative effects of green tea. The sedative effect was evaluated by examination of Monoamine oxidases (MAOs) inhibitory activity in vitro in the brain and liver of rat fed on green tea cultivated and harvested from the different regions and periods. It showed that methanol extracts of green tea inhibited significantly the brain MAO-A activity. Especially late harvested green tea extracts showed potential inhibitory activity. The liver MAO-B activity was also inhibited by all of the green tea extracts with strong intensity. This study confirmed that major compounds of green tea such as catechin, epigallocatechin-3-gallate (EGCG) and L-theanine, which were well known for the main bioactive components in the tea plants, were not associated with the MAO inhibitory activities of green tea. These results suggested that a MAO inhibition activity comes from other minor tea components we have to search in the future.

• Journal of Nutrition and Health
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• v.5 no.3
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• pp.109-125
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• 1972

According to the Sam-guk Sa-gi (History of three Kingdoms: Silla, Koguryo and Paeckje) tea was first brought into Korea by Kim Tae-ryeum, a diplomat, in 828 A.D. during the reign of king Hung-dot of Silla, and planted on the hill of Mt. Chi-ri. Afterwards, the tea trees were transplanted and cultivated by Buddists in many Buddist temples in southern provinces during the Silla and Koryo dynasties. People took much delight in drinking green tea, and specially the kings, buddist monks and nobilities of Silla and Koryo enjoyed drinking green tea. And eventually, the green tea became an indispensable part in all important ceremonies during the Koryo dynasty. After the Yi dynasty came into being, the dualistic philosophy of China was introduced and respected while buddist temples declined as a result of strong oppression by the ruling class. While temples were declined, the practice of drinking green tea was also declined. Nowadays we find many tea plants grow wild, which are seemed to be planted around buddist temples during the Koryo dynasty. Today, Korean people do not drink home made green tea. Instead, they like to take coffee, black tea and other tea products imported from foreign countries. Aa a result, Korea had to pay $ 520 thousand in 1969 to import foreign made tea and coffee. The natural conditions of southern provinces of Korea are very suitable in cultivating tea plants. If we develope the skill in producing good quality tea in Korea, we would be able to save the foreign exchanges that are being spent for importing foreign made tea products, and at the same time, we would be able to export our green tea to overseas. The quality of Korean green tea is as good as that of Japanese green tea. Green tea contains vitamin C while coffee and black tea do not contain it.

• Asian-Australasian Journal of Animal Sciences
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• v.27 no.11
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• pp.1571-1576
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• 2014

Nutritive values of green and black tea by-products and anti-nutritive activity of their tannins were evaluated in an in vitro rumen fermentation using various molecular weights of polyethylene glycols (PEG), polyvinyl pyrrolidone (PVP) and polyvinyl polypyrrolidone as tannin-binding agents. Significant improvement in gas production by addition of PEG4000, 6000 and 20000 and PVP was observed only from black tea by-product, but not from green tea by-product. All tannin binding agents increased $NH_3$-N concentration from both green and black tea by-products in the fermentation medium, and the PEG6000 and 20000 showed relatively higher improvement in the $NH_3$-N concentration. The PEG6000 and 20000 also improved in vitro organic matter digestibility and metabolizable energy contents of both tea by-products. It was concluded that high molecular PEG would be suitable to assess the suppressive activity of tannins in tea by-products by in vitro fermentation. Higher responses to gas production and $NH_3$-N concentration from black tea by-product than green tea by-product due to PEG indicate that tannins in black tea by-product could suppress rumen fermentation more strongly than that in green tea by-product.

• Food Science of Animal Resources
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• v.41 no.5
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• pp.840-854
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• 2021

The impact of green tea extract powder and rosemary extract powder, alone or in combination, on the quality characteristics of naturally cured pork sausages produced with white kimchi powder as a nitrate source was evaluated. Ground pork sausages were assigned to one of seven treatments: control (0.01% sodium nitrite and 0.05% sodium ascorbate), treatment 1 (0.3% white kimchi powder and 0.05% green tea extract powder), treatment 2 (0.3% white kimchi powder and 0.1% green tea extract powder), treatment 3 (0.3% white kimchi powder and 0.05% rosemary extract powder), treatment 4 (0.3% white kimchi powder and 0.1% rosemary extract powder), treatment 5 (0.3% white kimchi powder, 0.05% green tea extract powder, and 0.05% rosemary extract powder), and treatment 6 (0.3% celery juice powder, 0.05% green tea extract powder, and 0.05% rosemary extract powder). Naturally cured products had lower (p<0.05) cooking yield and residual nitrite content than control sausages. However, compared to the control, naturally cured products with white kimchi powder (treatments 1 to 5) showed similar the pH, oxidation-reduction potential, CIE L^* values, CIE a^* values, nitrosyl hemochrome content, total pigment content, and curing efficiency to the control. When the amount of green tea extract powder or rosemary extract powder was increased to 0.1% (treatments 2 and 4), lipid oxidation was reduced (p<0.05). These results indicate that green tea extract powder, rosemary extract powder, and white kimchi powder may provide an effective solution to replace synthetic nitrite and ascorbate used in traditionally cured products.

• The Korean Journal of Food And Nutrition
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• v.31 no.3
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• pp.416-424
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• 2018

The physiologically advantageous aspects of green tea have been identified recently and green tea has been a favorite drink of many people. Due to the increased awareness of green tea's positive effects on human health, the demand for foods containing green tea has increased. This has led to the development of diverse green tea-related beverages; thereby many companies in Korea have put a wide variety of manufactured green tea beverages on the market. However, the components within green tea beverages have not been examined in Korea yet. In this study, we investigated the contents of the physiologically functional materials found in green tea, such as catechin, catechin gallate, epicatechin, epicatechin gallate, epigallocatecin gallate, gallocatechin gallate and caffeine. Fifty-six green tea products purchased from the local grocery stores and cafes were analyzed using high performance liquid chromatography (HPLC) analysis. As a result, all tested products contained catechin and caffeine, although the amount of each component was largely different. The total amount of catechin derivatives in the manufactured green tea beverages purchased from cafes was 263.17 mg/L, while they were 61.99 mg/L in the beverages purchased from the local grocery stores. And, to the almost samples the amount of caffeine was proportional to the amount of catechin.