• Journal of Nutrition and Health
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• v.14 no.2
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• pp.71-79
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• 1981

The purpose of this paper is to find out whether Du-chung tea and Du-chung tea added with Stevia leaves are suitable for everyday use of diabetics. For this purpose, states of diabetic rabbit, induced by giving alloxan to normal rabbit, were examined in two cases. One was to administer Du-chung tea sweetened by sugar to the above same animal and the other to apply Du-chung tea sweetened by Stevia leaves, instead of sugar, under the equal condition. A study was carried out to determine the effects on blood sugar level, contents of BUN (blood urea nitrogen) and total cholesterol, and GPT (glutamic pyruvate transaminase) activity in both groups. The following results were obtained. 1) Sweetness of Du-chung tea added with 0.3-0.5% Stevia leaves was never to the standard sweetness. 2) Sweetness of Du-chung tea with 2% sugar plus 0.2% Stevia leaves was the nearest to the standard sweetness. 3) Du-chung tea with 0.5% Stevia leaves was recognized as the most effective the next was Du-chung tea no sweetening, and the worst was Du-chung tea with sugar. Addition of 0.2% Stevia leaves without lessening sugar concentration of the above Du-chung tea showed the same result as Du-chung tea with sugar. 4) Du-chung tea with Stevia leaves and Du-chung tea without sweetening had the tendency of reducing the total cholesterol content in serum, while only Du-chung tea with Stevia leaves presented remarked difference after 4, 6 and 10 days, when they were compared with control group. 5) Degree of CPT, activity had in general the similar tendency- to that of total cholesterol content. 6) Taken Du-chung tea with Stevia leaves and Du-chung tea without sweetening, the BUN content showed reducing tendency in small quanity, but, having little defference from control group.

• Journal of the Korean Society of Food Science and Nutrition
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• v.27 no.1
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• pp.87-92
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• 1998

Major characteristics of shrinking and rehydration of Korean tea-leaves were investigated in the hot-air drying equipment. Experiments were performed with various drying temperature, plucking time, heating method and rolling condition. The values of shrinking raito and rate were the highest at 7$0^{\circ}C$ in the range of 3$0^{\circ}C$ to 9$0^{\circ}C$. The 1st tea-leaves and showed higher values. Shrinking ratio was 16.62 and 19.62% for leaves and stems; shrinking rate was found 0.083 and 0.091cm/hr.cm, respectively. The rehydration characteristics of tea-leaves at the drying temperature of 3$0^{\circ}C$ were fairly satisfactory. The 2nd tea-leaves showed higher value than others, while the natural tea-leaves were lower. Average rehydration ratio and rehydration rate constant were 85.7% and 0.063/min for leaves; 80.1% and 0.032/min for stems, respectively.

• The Korean Journal of Community Living Science
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• v.18 no.1
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• pp.107-129
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• 2007

The purpose of this research is to understand features of the present condition of green tea food by analyzing the data on tea foods presented in Korean literature after the 1990's (two articles from professional journals related to tea culture, and three books related to tea food). The main conclusions are as follows: 1. It is found from separating 354 different kinds of green tea foods into three categories - main dishes, side dishes and desserts - that there are 137 kinds of side dishes, 123 kinds of desserts, and 94 kinds of main dishes from green tea foods. Upon dividing these into smaller categories, there are 40 rice dishes, 27 noodle dishes, 18 gruel dishes and 9 dumpling dishes found among the main dishes; 26 pan fried dishes, 24 potherb/cooked potherbs dishes, 17 deep-fried dishes, 15 soup/broth dishes, 14 grilled dishes, 11 smothered dishes, 10 hard -boiled/fried dishes, 6 kimchi dishes, 4 dried food dishes, 4 jelly dishes, 4 stew dishes, and 2 raw fish dishes among the side dishes; and 37 snack dishes, 36 punch/drink dishes, 26 rice cake dishes, and 24 bread dishes are found among the desserts. 2. There are 201 kinds of green tea foods using powders, 107 kinds using wet tea leaves, 61 kinds using dry tea leaves, 57 kinds using water of drawn tea, and 17 kinds using wild tea leaves, according to analysis of teas used for green tea foods. There is more use of powder for snacks, punch and drinks, rice cakes, noodles, and breads, and more use of wet tea leaves for rice, pan fried food, and potherb/cooked potherb dishes. It is also shown that there is more use of water from drawn tea for rice, punch and drinks, noodles, and gruels, more use of dry tea leaves for snack, rice, breads, and more use of wild tea leaves for deep-fried and pan fried kinds of tea foods.

• Journal of Applied Biological Chemistry
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• v.53 no.1
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• pp.56-59
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• 2010

An optimal manufacturing process was established for the mass-production of mulberry leaves tea. The produced tea contained abundant dietary fibers, $\beta$-carotenes, and calcium. Also the polyphenol content and antioxidant activity of mulberry leaves tea were higher than those of simply dried mulberry leaves. These results imply that this tea manufacturing process is effective to utilize the useful components of mulberry leaves.

• Analytical Science and Technology
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• v.8 no.4
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• pp.877-880
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• 1995

The determination of fluoride and the nutritious calcium in infusion of teas are explained. Tea leaves were pulverized and were immersed in boiling water. The solution was filtered and fluoride, calcium and oxalic acid were determined by the ion chromatography. The quantities of fluoride, calcium and oxalate ions extracted from 100 g of tea leaves were calculated. Tea leaves were also immersed in 0.5 M hydrochloric acid and extracted oxalate and calcium ions were analyzed. The free oxalic acid and calcium were extracted in boiling water and the total ones were extracted in hydrochloric acid. The quantity of calcium oxalate was calculated from the total and the free oxalic acids. The free calcium was estimated to be nutritious.

• Food Science and Preservation
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• v.11 no.2
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• pp.175-181
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• 2004

As a foundational study for notifing excellence of persimmon leaves tea, the chemical component and antioxidant activity were investigated in persimmon leaves from Dungsi, Gabjubaekmok, Weulhasi and Cheongdobansi and green tea leaves. Total sugar contents in all persimmon leaves more higher than that of green tea leaves, and the highest free sugar contained in persimmon and green tea leaves was sucrose. Free sugars present in persimmon and green tea leaves were composed of sucrose, glucose, fructose, maltose and xylose. Sucrose and fructose took more than 70% of total sugar contents. 31∼32 kinds of amino acid were detected in persimmon leaves and 35 kinds in green tea leaves. And total amino acids contained in persimmon leaves were Dungsi, Gabjubaekmok, Weulhasi and Cheongdobansi, respectively 60.40 nmol/${\mu}$L, 53.21 nmol/${\mu}$L, 52.29 nmol/${\mu}$L and 47.58 nmol/${\mu}$L. Total amino acid contents in green tea leaves was the most abundant of all as 114.72 nmol/${\mu}$L. The contents of vitamin C in persimmon and green tea leaves were in the range of 0.015∼0.089% and 0.01%, respectively. Vitamin C was significant higher content in the persimmon leaves than in green tea leaves. Caffeine was not detected in all persimmon leaves, but the caffeine content of green tea leaves was 6.63 mg/l00 g. The content of catechin was showed in the orders of Cheongdobansi, Gabjubaekmok, Weulhasi, Dungsi and green tea leaves; 0.35%, 0.34%, 0.24%, 0.18% and 0.07%, respectively. The contents of gallic acid in Dungsi and Gabjubaekmok were 0.32% and 0.20%. That of green tea was 1.41%, it was the highest content in all samples. The content of calcium in Chengdobansi was most abundant in all samples as 3516.14 ppm, it was 4∼5 times as that of green tea leaves. Flavor component pattern among persimmon leaves was similar, but that of green tea leaves was different. The IC50(${\mu}$g) value of Dungsi, Weulhasi, Gabjubaekmok, Cheongdobansi and green tea were 64.5, 42.0, 47.0, 64.0 and 19.0 respectively.

• Korean Journal of Food Science and Technology
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• v.39 no.3
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• pp.246-254
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• 2007

Fresh tea leaves grown in Jeju Island and Jeonnam Province of South Korea were plucked and processed. Volatile compounds (VCs) were analyzed and identified with SPME-GC/GC-MS/GC-O. The VCs of green teas were classified into two major categories based on their aroma characteristics: the Greenish (Group I), and Floral (Group II) odorants. It was found that the VCs were decreased significantly in fresh tea leaves as they were plucked at the later stages of cultivation. The ratio of VCs responsible for Group I and Group II compounds was well-balanced in tea leaves plucked in May, but the balances were changed when the fresh leaves were processed. The major VCs of fresh tea leaves in Jeju and Jeonnam were n-hexanal, E-2-hexenal, Z-3-hexenal, myrcene, benzyl alcohol, linalool, and phenyl alcohol. Also, Jeju and Jeonnam tea leaves had different aroma composition. n-Heptanol, ${\beta}-pinene$, benzaldehyde, and ethyl salicylate were found in Jeju fresh tea leaves, and Z-3-hexenol, E-2-hexenol, and methyl n-heptanoate were detected in Jeju dry tea leaves. On the other hand, Z-linalool oxide and myrcene were found in Jeonnam dry tea leaves. The SPME-GC method showed high reproducibility (RSD, 7.4%) with no-artifact formation. In this study, optimum plucking period of tea leaves could be determined for production of high quality green tea with a well-balanced aroma and characteristic VCs in green tea according to growing areas.

• Journal of the Korean Society of Food Culture
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• v.14 no.2
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• pp.167-175
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• 1999

This study examines the effects of the Korean horticultural foods which are, by traditional wisdom, supposed to contain anti-aging substance. All twenty three kinds of plants are chosen as a sample for the experiment in which the content of three main anti-aging nutrients, -carotene, Vitamin C, and Vitamin E are respectively measured by Nilis, Colorimetric, and AOAC method. The result shows: among the samples, top six plants that contain the most -carotene content are high quality tea(Camellia sinensis), thistle(Cirsium japonicum Var.), Angelica keiskei, mulberry leaves(Morus alba l.), field horsetail(Equisetum arvensa), and carrot(Daucus carota), in order; top four for a Vitamin C contents are low quality tea, mulberry leaves, pine leaves(Pinus densiflora), and high quality tea, in order; top four for a Vitamin E contents are persimmon leaves(Diospyros mongolicum) tea, high quality tea, low quality tea, and pine leaves, in order. Drying or boiling process increases the content of -carotene and Vitamin E in high quality tea, dropwort(Oenanthe javanica), field horsetail, and wild aster(Ligularia stenocephala Marsumum et Koldzumi), while, in case of mulberry leaves, drying process lowers them. Vitamin C content strikingly decreases in heating and drying process.

• Journal of Applied Biological Chemistry
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• v.53 no.2
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• pp.116-119
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• 2010

A Maengjong-juk (Phyllostachys pubescence) leaves tea was prepared by using a series of drying/roasting and rolling processes. The produced tea contained abundant dietary fibers (60.42%), $\beta$-carotenes (7.9 mg RE%), and calcium (437.1 mg%). Also the polyphenol content ($155.33\;{\mu}g/g$-tea) and DPPH free radical scavenging activity ($IC_{50}=212\;{\mu}g/mL$) of Maengjong-juk leaves tea were greatly higher than those of simply dried leaves. These results imply that the tea preparation is effective to utilize the useful components of Maengjong-juk leaves.

• Korean Journal of Food Science and Technology
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• v.31 no.1
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• pp.20-23
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• 1999

This study was conducted to investigate the content and composition of tea catechins at different plucking time and different position of tea leaves. The bud and first leaf, second leaf, third leaf, and fourth leaf were collected on May, July, and August. The catechin content was highest in leaves picked on August among those collected from different months. When compared with the different part of tea leaves, the bud and the first tea leaf contained the highest catechin, and the fourth left contained the lowest catechin. Analysis of catechin composition in the tea leaves, showed that epigallocatechin gallate was the highest, and the other contents were following order: epicatechin gallate, epicatechin, epigallocatechin.