• Korean Journal of Agricultural and Forest Meteorology
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• v.14 no.4
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• pp.246-253
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• 2012

Despite frequent freezing injury to tea trees due low temperature, drought, and strong wind during wintertime, no comprehensive measurements have been taken. We selected and examined 9 locations in Hwagae-myeon and 4 places in Agyang-myeon, Hadong-gun, Gyeonsanggnam-do where low temperature damage had occurred between December 2010 and February 2011. Our objective is to examine the effect of frost damage on the morphological symptom and harvest of a tea tree exposed to a constant low temperature environment during wintertime. The results of our analyses on meteorological environment, tea leaf chromaticity, water content and trypan blue are as follows: (1) the number of days with temperature of $-10^{\circ}C$ or less, which were subject to frost damage to a tea tree were 8 and 13.6% during the winterization period in 2011; (2) the accumulated time was 1,308 minutes, and the longest duration at $-10^{\circ}C$ was 588 minutes from 21:08 p.m. 15 January to 7:30 a.m. $16^{th}$ January. The rainfall was only 104 mm which was 306 mm less than the previous year; (3) the lightness L values in 2011 were higher than in 2012 due to dehydration and necrosis by blue discoloration and red discoloration at all areas in chromaticity measurement; (4) the water content in a tea leaf in 2011 was higher than in 2012 due to low rainfall and strong wind, and almost no cell death phenomenon was observed from normal tea leaves subject to no low temperature stress in a trypan blue analysis; and (5) partial coloration due to cell death, however, took place in the leaves damaged by blue discoloration subject to low temperature stress, and most coloration due to cell death took place in the leaves damaged by red discoloration.

• Animal cells and systems
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• v.13 no.2
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• pp.133-139
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• 2009

Green tea seed was extracted with absolute ethanol,and the green tea seed extract(GTSE)was subjected to assays for toxicity, antioxidant ability, angiogenesis inhibitory effects and cell adhesion, as well as western blotting, and an in vivo experiment against 4 high-ranking adult cancers in Korea. Our series of experimental data demonstrated that GTSE has an antioxidant ability superior to that of EGCG in the green tea leaf, and also exhibits a profound high tumor growth inhibitory activity on a variety of cancer cell lines, as well as nude mice infected with cancer cells. GTSE was identified as a natural anticancer compound showing excellent angiogenesis inhibition and cancer cell suppression abilities. Our preliminary observations also indicate that GTSE may be another potential source of natural dietary antioxidants and also may be applicable as a novel natural anticancer agent.

• Korean Journal of Food Science and Technology
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• v.53 no.3
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• pp.267-277
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• 2021

To evaluate hepatoprotective effects, the antioxidant capacities of matcha green tea extract (Camellia sinenesis) were compared to those of green leaf tea and the anti-inflammatory activities in HepG2 cells were investigated. Evaluation of the total phenolic and total flavonoid content, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, and inhibitory effect on lipid peroxidation indicated that the aqueous extract of matcha green tea presented significant catechin content and antioxidant capacity compared to those of green leaf tea. In addition, the extract had considerable inhibitory effects on α-glucosidase, α-amylase, and advanced glycation end-products. The matcha green tea extract significantly increased cell viability and reduced reactive oxygen species in H₂O₂- and high-glucose-treated HepG2 cells. Furthermore, in response to oleic acid-induced HepG2 cell injury, treatment with matcha green tea aqueous extract inhibited lipid accumulation and regulated the expression of inflammatory proteins such as p-JNK, p-Akt, p-GSK-3β, caspase-3, COX-2, iNOS, and TNF-α. Matcha green tea could be used as a functional material to ameliorate hepatic lipid accumulation and inflammation.

• Korean Journal of Medicinal Crop Science
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• v.12 no.3
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• pp.183-190
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• 2004

The major compositions of leaf tea and flower tea were investigated to develope as a new functional tea using Korean native Camellia japonica L. Most of leaf teas, except flower tea, were considered as good materials with basic conditions for tea manufacture because water content was below 6%. Crude protein was the greatest component in roasted young leaf tea (RYLT), crude fats in roasted mature leaf tea (RMLT) and ashes in fermented young leaf tea (FYLT). Caffein were present as the highest amount (5.18%) in steamed mature leaf tea (SMLT), showing less amount than green tea. Catechin were contained as the highest amount in all kinds of teas, especially FYLT was the highest (9.57%). Tannin, which highly related with tea quality including astringent taste, color and perfume, were present as the highest amount in FYLT. Vitamin C was highly detected in the tea from flowers (22.7 mg/l00 g) rather than in the tea from leaves. The content of theanine were found in flower tea by 1,074 mg/l00 g, and had about twofold of FYLT and RYLT. Among free amino acids, glutamic acid and aspartic acid were higher detected in SMLT and RMLT while asparagine was present as higher amounts in RYLT and FYLT, expecting these components can improve tea taste. Nucleic acids and their derivatives including GMP, hypoxanthine and AMP were detected as the higher amounts by 7.86, 8.57, and $12.67\;{\mu}mol/g$, respectively, however IMP content was even reduced by all manufacturing processes. In all kinds of tea, sugars such as glucose, fructose, sucrose and maltose were detected, specially glucose and fructose were found as highest amount in RFT by 65.5 and 59.6 nmol/0.1 mg, respectively.

• Journal of Applied Biological Chemistry
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• v.55 no.2
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• pp.95-101
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• 2012

Nutritional components of Ojuk leaf tea and Ojuk shoot tea prepared from the leaves and shoots of black bamboo (Phyllostachys nigra Munro) by tea manufacturing process were evaluated. In addition, the extraction yield of water soluble components from these teas in the general tea brewing condition (water extraction in $80^{\circ}C$ for 10 min.) and the contents of polyphenol and flavonoid were compared with not only the dried raw materials, but also green tea and mate tea. Finally, offline and online scavenging activities against 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) and di(phenyl)-(2,4,6 trinitrophenyl)iminoazanium free radicals were investigated to evaluate the antioxidant activity and explore the components showing ABTS free radical scavenging activity from tea infusion. These results demonstrated that these teas from black bamboo contain various nutritional components and can be used as traditional tea beneficial to human health.

• Journal of the Korean Chemical Society
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• v.63 no.2
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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.

• Korean Journal of Food Science and Technology
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• v.40 no.5
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• pp.485-490
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• 2008

In this study, organic tea leaves were characterized with the aim of developing an organic beverage process. The green tea leaves grown using organic farming techniques were collected in Haenam, Korea. Catechins in green tea leaves were extracted by chloroform and ethyl acetate and these were then analyzed quantitatively and qualitatively by HPLC (high pressure liquid chromatography). The color and pH values of the green tea extracts were also measured. The catechin levels of April-harvested, May-harvested and June-harvested, semi-fermented leaves at 0.5% were 66.24, 29.19, 57.11, and 5.27 ${\mu}g/mL$, respectively. Among the detected catechins, the level of (-)-epigallocatechin gallate was the highest while that of (-)-epigallocatechin was not detected. The June-harvested leaves were selected as raw material for development of the green tea beverage, based on the levels of catechins, economic viability and yield of tea extract. As the level of extract increased, the levels of catechins of 0.1, 0.2, 0.5% also increased by 1.5, 11.78 and 41.01 times. From the results of the sensory evaluation of June-harvested leaf-extract, the sensory score of color was the highest in 0.1%, while the flavor and overall quality were the highest in 0.2%.

• Journal of the Korean Society of Food Science and Nutrition
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• v.46 no.5
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• pp.639-645
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• 2017

Differences in bioactive compounds and antioxidant activities of aronia leaf (AL) extracts according to manufacturing conditions such as different number of pan-roasting and different temperatures were investigated. Both total polyphenolic compounds and total flavonoids contents were the highest in six time-pan-roasted AL tea extract ($37.96{\pm}0.48mg$ catechin equivalent/g and $19.96{\pm}0.44mg$ quercetin equivalent/g, respectively) among four tea samples. Antioxidative activities were also the highest in six time-pan-roasted AL tea extract with $IC_{50}$ 0.43 mg/mL and $IC_{50}$ 0.27 mg/mL based on DPPH and ABTS radical scavenging activities, respectively. HPLC analysis revealed that AL tea infusion did not have caffeine regardless of manufacturing conditions, whereas green tea infusion had 3.8 mg/g caffeine. Results demonstrated that AL tea can be expected as caffeine free leaf tea containing antioxidant benefits. Moreover, specific pan-roasting conditions of AL tea would be very important for its functional and sensory attributes.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2007.11a
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• pp.366.1-366.1
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• 2007

• The Korean Journal of Food And Nutrition
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• v.27 no.3
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• pp.421-426
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• 2014

The objective of this study is to propose an export strategy due to an analysis of USA and Japan consumer's perception and willingness-to-pay for flower tea. For that, we conducted a survey on the consumer's perception on flower tea compared with leaf tea such as green tea. We also analyzed the willingness to purchase and pay for it. The reasons of drinking of flower tea for USA consumer are 'flavor'-followed by 'taste', and for Japanese consumer 'relaxation'-followed by 'flavor' in order. Both of them consider 'quality', 'safety'- and 'origin' in order when they purchase flower tea. USA consumers have a willingness-to-pay of about 8.3% and Japanese consumers have a willingness-to-pay of about 29.1%. Based on those results, it is necessary to differentiate the process and marketing strategies for the export of flower tea.