• Journal of agriculture & life science
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• v.46 no.2
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• pp.49-61
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• 2012

This study was carried out to investigate the chemical composition and the inorganic constituents of the green tea at the 3 picking periods (Ujeon, Sejag, Jungjag) in Hadong. The results as follows ; The contents of chlorophyll, tannin, vitamin-c and total catechin were increased as picking periods increased but the contents of total nitrogen, total free amino acids, theanine and caffeine were decreased on the reverse. The inorganic constituents Mg, Ca and Mn were increased as picking periods getting late but the Na, K, B contents were decreased on the reverse. The contents of the total nitrogen, chlorophyll, total free amino acid, theanine, caffeine and total catechin and Na, Mg, Ca, B and Se were insignificant differences between Ujeon and Sejag.

• Korean Journal of Food Science and Technology
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• v.52 no.5
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• pp.427-434
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• 2020

This study was performed to compare nutritional compounds and physiological functions of five domestic and imported green tea cultivars at three time points. The five cultivars were compared for theanine, γ-aminobutyric acid, and catechin content by LC-MS/MS and HPLC. Furthermore, the five tea cultivars were functionally characterized with respect to antioxidant activity, brain cell protective effect, and inhibitions of α-glucosidase and HMG-CoA reductase activities. Among green tea cultivars, Chamnok had the highest content of catechins (198 mg/g DW), theanine (11.89 mg/g DW), and tannin (23.6 mg/g DW). Considering functional properties, Chamnok treatment resulted in the maximum viability of brain cells and reduced the cortisol content of SH-SY5Y cells. The inhibition of α-glucosidase and HMG-CoA reductase was the strongest following Chamnok treatment (72.9% and 69.8%, respectively). These results indicate that Chamnok could be optimal for consumption or favorable processing owing to its high nutritional compounds, such as theanine and catechin, and remarkable brain cell protective effects.

• Korean Journal of Medicinal Crop Science
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• v.9 no.1
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• pp.33-39
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• 2001

The split application of a nitrogen fertilizer was applied at the levels to 3, 4, 5, 6 and 7 time. The results of yield and quality of Okro tea are summarized as follows: Among five treatments, the growth and yield were somewhat more excellent in the five time split treatments compared with other treatments. The chemical components such as total nitrogen, total amino acid and vitamin C were somewhat higher in the five time split treatment compared with other treatment. However, the content of components such as tannin, caffeine, chlorophyll were not different among plots of $4{\sim}7$ time split application except three time split application manuring. The content of fatty acid was producted $2,888{\sim}2,933mg/100g$. Especially, the content of oleic acid, linoleic acid and linolenic acid was the higheat in the five time split application. Sixteen kinds of free amino acid including theanine as a good taste component of Okro tea were isolated and measured by HPLC. Theanine in the five time split application was higher with value of $72{\sim}513mg/100g$ than in other treatment. In scoring test, tea appearance and interal qualities of 3 time split application become lower than any other treatment as 80.2 point, while five time application had the highest with 84.7 point. Conquently, those results meant that five time split application was optimum split application of fertilizer for high yield and good quality of Okro tea.

• Proceedings of the Korean Society of Food Science and Nutrition Conference
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• 2001.12a
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• pp.48-49
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• 2001

• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.1
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• pp.58-61
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• 2003

Moisture content was 79.5%, banjhi shoot was 77.8% of the total and the weight was 29.4 g/100 buds in the harvested plant leaves used for manufacturing Okro tea. Okro tea heated at 75$^{\circ}C$ for 30 min showed the best quality among all the treatmants. Chemical components such as total nitrogen, theanine, arginine and chlorophyll were high in the tea treated at 75$^{\circ}C$ for 30 min compare with those of other treatments. The sensory evalution test In terms of appearance shape color and taste showed greater preferences in Okro tea treated at 75$^{\circ}C$ for 30 min than those of other treatments. The results suggested that heat treatment at 75$^{\circ}C$ for 30 min was the best condition for the final rolling process in manufacturing of Okro tea.

• Korean Journal of Medicinal Crop Science
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• v.4 no.3
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• pp.247-254
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• 1996

The effect of shading on mineral elements, free amino acids, and fatty acids content of tea shoot was examined under different shading periods. The results are summarized as follows. The con­tent of $NH_4^+$, $K^+$. $Mg^{++}$, $PO_4^{--}, was increased, but that of $Na^+$, $Ca^{++}$, $F^-$, $Cl^-$, $No_3^-$, $So_4^{--}$ was de­creased with the passage of shade treatment periods. The content of Total- Nitrogen of tea shoot was the highest in the 55% 10days+95% 5days shading as 6.07%. The content to Total Free Amino Acid was hagher ranged from 20mg/100g to 80mg/100g in shading treatment compered with the un shading treat­ment. The content of Theanine was the highest in 55% 10days+95% 5days shading as 1834mg/100g,while that of unshading was the lowest as 1247mg/100g. The content of Theanine was decreased with the passage of shading periods. The content of Fatty Acid was the highest in the 55% 15days+95% 15days shading as 3164mg/100g, while the unshading treatment had the lowest in the 55% 5days+95% 5days as 2435mg/100g.

• Food Science and Preservation
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• v.14 no.6
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• pp.709-715
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• 2007

Korean green tea has been claimed to have health-promoting effects, which may be related to the antioxidant activity in vitro. Korean green teas (Woojeon, WJ ; Sejak, SJ ; Jungjak, JJ ; Daejak, DJ) were subjected to different harvested times and yet little research has examined their bioactive compounds. To assess the effect of this different harvested times on nutritional and health-related properties such as Korean green tea polyphenols, flavonoids, theanine and free amino acids, antioxidant activities and radical scavenging activities were determined. Total polyphenols in JJ (37.16 mg/g) was higher than in other products (WJ, 19.55 ; SJ 24.65 ; DJ, 23.28 mg/g). Contents of flavonol and flavone glycosides were the highest at DJ (350.83 mg%) as compared to WJ (220.81), SJ (256.88) and JJ (270.36 mg%). Contents of theanine and total free amino acids were the highest at WJ (14.11, 23.62 mg/g, respectively), but decreased thereafter. Antioxidant activities were higher in JJ and DJ, using the linoleic acid peroxidation, DPPH and ABTS free radical-scavenging activities. However, WJ and SJ had less active antioxidant activity and free radical-scavenging activity. Reducing powers were increased depend on the concentration of extracts. Antioxidant activity and free radical-scavenging activity of JJ and DJ seemed to relate with total polyphenol and flavonoid contents.

• Korean Journal of Food Science and Technology
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• v.24 no.4
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• pp.315-319
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• 1992

Korean green tea leaves which were harvested three times(May, June, August) were treated with anaerobic conditions and were measured changes of ${\gamma}-aminobutyric$ acid(GABA) and other constituents. In anaerobically treated green tea leaves, the content of ${\gamma}-aminobutyric$ acid(GABA) and alanine increased while glutamic acid decreased. Whereas theanine, arginine, caffeine and tannin showed little change and the content of vitamine C slightly decreased with the passing of the anaerobic treatment time. Formation of GABA, a hypotensive constituents, was proportioned to the content of glutamic acid and the optimum time of the anaerobic treatment was about 12 hours. In the anaerobic treatment of green tea leaves, effect of nitrogen gas and vacuum condition was no difference between two.

• Korean Journal of Food Science and Technology
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• v.36 no.4
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• pp.542-546
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• 2004

Changes in contents of catechins, caffeine, free amino acids, and minerals in green tea loaves according to harvest periods were compared. Total catechin content increased from 40.61 to 52.04 mg/g, while that of caffeine decreased from 17.56 to 14.61 mg/g according to harvest periods. Regardless of harvest periods, composition of catechins was epigallocatechin (EGC)>epigallocatechin gallate (EGCg)>epicatechin (EC)>gallocatechin (GC)>epicatechin gallate (ECg)>catechin (C)>gallocatechin gallate (GCg)>catechin gallate (Cg). Free amino acid content in green tea leaves was highest in young loaves, and gradually decreased according to harvest periods. Theanine content was markedly decreased with leaf aging, suggesting taste of green tea may be changed from mild to bitter with increasing harvest period. Analyses of mineral elements in green tea leaves showed that Fe, Mn, and Mg increased with leaf aging, while Cu showed opposite trend. Results reveal that content of some chemical compounds in Korean (Posong) green tea was highly dependent on harvest period.

• Korean Journal of Medicinal Crop Science
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• v.11 no.3
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• pp.190-194
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• 2003

A field experiment was conducted to evaluate effect by split-application of slow-release fertilizer on the tea plant. The yield of the 2nd harvested tea leaves was not different to the slow-release fertilizer of two time split manuring had been doing Sep. or Mar. compared with the traditional manuring had been doing four time split manuring, but that of the slow-release fertilizer to one time split manuring in Sep. had decreased $12.5{\pm}1.5%$. In case of the 2nd harvested leave, the contents of chemical components related to quality such as total nitrogen, total amino acid were somewhat higher in the slow-release fertilizer (two time split manuring) than in the traditional manuring, but those of tannin, and caffeine were low, and those of chlorophyll, vitamin C, free sugar and theanine were not different to out of treatments. In scoring test, appearance and quality of green tea were more excellence 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, I thought that use of slow-release fertilizer be increased yield and quality of tea leaves, and improved efficiency nature of nitrogen, phosphate and potassium out of soil fertilizer components.