• Culinary science and hospitality research
• /
• v.16 no.4
• /
• pp.220-229
• /
• 2010

Brewing tea with regular teapots can cause a problem in keeping the temperature of the tea. Cold weather, a cold teapot, and/or the temperature of tea leaves make tea cold, lowering the temperature of the tea leaves that can also make the flavor of the tea leaves worse. This experiment shows both the problem and the solution to the temperature problem of tea leaves. To maintain the appropriate temperature and reduce the problem, we researched and developed a special straw for tea leaves as a result of this experiment The straw consists of various filtering holes(diameter 1~2 mm) with the height of 5 mm from the very bottom of the straw. Using the straw is better to keep higher temperature, better flavor, and the smell of tea. Also, the sensory evaluation shows that the overall taste of tea is improved(p<0.05).

• The Plant Pathology Journal
• /
• v.17 no.6
• /
• pp.350-353
• /
• 2001

In 2001, a black scab disease was observed in tea plant (Thea sinensis) cultivated in the hillsides of Hwngaemyon and Hadong-gun, Gyeongnam province, Korea. The disease symptoms initially appeared on leaves, green twigs and stems, showing small dark brown spots on the infected areas, which gradually expanded. A fungus was isolated from diseased leaves and green twigs. It grew readily on potato dextrose agar, forming dark green to dark gray colonies. The optimum temperature for mycelial growth was about 20$^{\circ}C$. The diameter of growing hyphae was 3.5-5.8 $\mu\textrm{m}$. Conidia were ellipsoidal, ovoid or subspherical, and mostly one-celled but occasionally septate. The size of one-celled and septate conidia were 3.7-12.4${\times}$3.4-5.2 $\mu\textrm{m}$ and 9.3-18.7${\times}$3.8-7.2 $\mu\textrm{m}$, respectively. Conidia were formed in long branched chains on the erected conidiophores, which were dark brown in color and 28.9-218.3${\times}$3.0-6.1 $\mu\textrm{m}$ in length. The fungus was identified as Cladosporium herbarum on the basis of its morphological characteristics. The black scab disease occurring in tea caused by Cladosporium herbarum has not been previously reported in Korea.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.37 no.8
• /
• pp.1025-1029
• /
• 2008

Fresh green tea leaf extracts were prepared by different enzyme treatment conditions, such as concentration, treating time and treating temperature using complex enzyme, Rapidase TF, and then extracted for 30 min at $80^{\circ}C$ to investigate their physicochemical properties. The results showed that free sugar content in every sample tended to increase, especially glucose content was increased up to 7.25 times compared to the control. Total amino acid was barely affected by the enzyme treatment and caffeine content was increased with reaction temperature. Total polyphenol and total catechin content was increased according to the amount of enzyme added and reaction temperature. Regardless of enzyme treatment conditions, composition of catechins were epigallocatechin, epicatechin, epicatechin gallate and epigallocatechin gallate by descending order of the content. Gallic acid content increased up to 0.04% and $45^{\circ}C$ with no further significant changes thereafter. From the results above, we could conclude that a simple and new method to extract green tea materials directly from fresh green tea leaves with improved extract ratio may be introduced by adding $0.08{\sim}0.1%$ of Rapidase TF to heat treated fresh green tea leaves and keeping temperature at $37{\sim}45^{\circ}C$ for $180{\sim}240\;min$ in order to skip existing complicated procedures.

• Asian Pacific Journal of Cancer Prevention
• /
• v.17 no.4
• /
• pp.1649-1654
• /
• 2016

Tea derived from the leaves and buds of Camellia sinensis (Theaceae) is consumed worldwide. Green tea contains various components with specific health-promoting effects, and is believed to exert protective effects against diseases including cancer, diabetes and hepatitis, as well as obesity. Of the various tea components, the polyphenol catechins have been the subject of extensive investigation and among the catechins, (-)-epigallocatechin gallate has the strongest bioactivity in most cases. Our research group has postulated that hepatocyte nuclear factor-$4{\alpha}$, sterol regulatory element-binding proteins, and tumor necrosis factor-${\alpha}$ are targets of green tea constituents including (-)-epigallocatechin gallate for their anti-diabetes, anti-obesity, and anti-hepatitis effects, respectively. Published papers were reviewed to determine whether the observed changes in these factors can be correlated with anti-cancer effects of green tea. Two major action mechanisms of (-)-epigallocatechin gallate have been proposed; one associated with its anti-oxidative properties and the other with its pro-oxidative activity. When reactive oxygen species are assumed to be involved, our findings that (-)-epigallocatechin gallate downregulated hepatocyte nuclear factor-$4{\alpha}$, sterol regulatory element-binding proteins, and tumor necrosis factor-${\alpha}$ may explain the anti-cancer effect of green tea as well. However, further studies are required to elucidate which determinant directs (-)-epigallocatechin gallate action as an anti-oxidant or a pro-oxidant for favorable activity.

• Natural Product Sciences
• /
• v.22 no.4
• /
• pp.270-274
• /
• 2016

Green tea, the leaves of Camellia sinsneis (Theaceae), is generally acknowledged as the most consumed beverage with multiple pharmacological functions including antioxidant activity. This study was performed to analyze the effect of extraction conditions of green tea on its antioxidant effects using DPPH assay. Three extraction factors such as extraction solvent (EtOH, 0 - 100%), extraction time (3 - 15 min) and extraction temperature ($10-70^{\circ}C$) were analyzed and optimized extraction condition for antioxidant activity of green tea extract (GTE) was determined using response surface methodology with three-level-three-factor Box-Behnken design (BBD). Regression analysis showed a good fit of data and the optimal conditions of extraction were found to be 57.7% EtOH, 15 min and $70^{\circ}C$. Under this condition, antioxidant activity of experimental data was 88.4% which was almost fit to the ideal value of 88.6%. As epigallocatechin gallate (EGCG) is known for the major ingredient for antioxidant activity of green tea, we investigated the effect of EGCG on antioxidant activity of GTE. EGCG showed antioxidant activity with the $IC_{50}$ value of $4.2{\mu}g/ml$ and a positive correlation was observed between EGCG content and the antioxidant activity of GTE with $R^2=0.7134$. Interestingly, however, GTE with 50 - 70% antioxidant activity contain less than $1.0{\mu}g/ml$ of EGCG, which is much lower than $IC_{50}$ value of EGCG. Therefore, we suppose that EGCG together with other constituents contribute to antioxidant activity of GTE. Taken together, these results suggest that green tea is more beneficial than EGCG alone for antioxidant ability and optimal extraction condition of green tea will be useful for the development of food and pharmaceutical applications

• Natural Product Sciences
• /
• v.7 no.2
• /
• pp.45-48
• /
• 2001

The antioxidative effect of the extracts from the leaves and fruits of Acer ginnala against free radicals was studied by two different methods using DPPH radical-generating system, and hydroxyl radical-generating system $(Cu^{++}/H_2O_2\;system)$ which induces DNA strand breaking. Compared with well known antioxidative plants, green tea, Scutellaria baicalensis, the Acer ginnala extracts showed excellent radical-scavenging activity in DPPH radical-generating system and inhibited effectively hydroxyl radical induced-DNA strand breaking in a concentration-dependent manner in $Cu^{++}/H_2O_2$ system whereas the green tea extract stimulated the strand breaking at a low concentration. These results suggest that he extracts from the leaves and fruits of Acer ginnula could be good antioxidative agents.

• Journal of agriculture & life science
• /
• v.43 no.3
• /
• pp.27-34
• /
• 2009

Green tea was prepared by soaking 1.5 g of green tea leaves into 100 mL of distilled water at $75^{\circ}C$ for 5 min. The green tea was stored at three different conditions - (A) green tea was stored at not-artificially excluding natural light condition, at natural air condition, and without addition of vitamin C; (B) green tea was stored at artificially excluding natural light condition by wrapping a vial with aluminium foil, at nitrogen filling up condition, and with addition of 30 mg/100 mL of vitamin C; and (C) green tea was stored at artificially excluding natural light condition by wrapping a vial with aluminium foil, at nitrogen filling up condition, and without addition of vitamin C. After 28 days of storage at $4^{\circ}C$, the chemical quality of the green tea was evaluated. Total phenolic contents of (A), (B), and (C) green tea decreased to 71.50, 73.88 and 75.07%, respectively, after storing for 28 days compared to those of beginning state. DPPH radical scavenging activities of (A), (B), and (C) green tea were 87.87, 92.93 and 88.39%, respectively. Epigallocatechin gallate (EGCG), the main active compounds of green tea, contents of (A), (B), and (C) green tea were 130.61, 136.47 and 4.34%, respectively. The results indicated that light, air condition, and vitamin C were significantly important to the chemical quality of green tea during storage.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.36 no.8
• /
• pp.1043-1047
• /
• 2007

The physicochemical characteristics of green tea prepared by four kinds of alkaline ionized water (AIW; pH 8.57, 8.85, 9.23, and 10.06, respectively) were evaluated. Green tea was made by soaking commercial green tea leaves in AIW at $75^{\circ}C$ for 10 min (1.0 g/100 mL). Total phenol contents, total flavonol contents, and ascorbic acid contents of green tea decreased with increasing pH of AIW. Increasing pH of AIW tended to decrease lightness (L) and redness (a) of green tea but increase yellowness (b) in Hunter color values. The amount of epicatechins and radical scavenging activity of green tea also decreased with increasing pH of AIW, while caffeine was not significantly affected. Tyrosinase inhibition activity was the highest in AIW of pH 8.85.

• Journal of Nutrition and Health
• /
• v.35 no.1
• /
• pp.24-29
• /
• 2002

Present study investigates the protective effects of green tea against acute ethanol administration on lipid peroxidation and antioxidant system in various regions of rat brain ; cortex, cerebellum, striatum and hippofampus. The following parameters were examined : malondialdehyde(MDA) concentrations and activities of superoxide dismutase(SOD), catalase and glutathione peroxidase(GSH-Px). Male Sprague-Dawley rats of 9 month old were given control diets or those containing 1% green tea powder for 4 weeks, and at tole end of feeding each diet group was received acute ethanol(5g/kg body weight) or equicaloric sucrose solution administration. Results indicated that green tea powder significantly decreased malondialdehyde(MDA) levels in the striatum(81.85nmol/g tissue) and hippocampus(71.68nmol/g tissue), compared to control group(145.68nmol/g tissue in the striatum, 119.04nmol/g tissue in the hippocampus). Also, a significant decrease was observed in the striatum of green tea-ethanol treated group compared to control group. Green tea significantly blocked an ethanol-induced catalase activation in the hippocampus, which means an ethanol administration drew a significant increase only in control diet groups. In conclusion, these results suggest that moderate consumption of green tea leaves ctrl have protective effects against ethanol induced oxidative stress on various regions of rat brain, by significantly reducing MDA concentrations in the striatum and hippocampus and inhibiting ethanol induced catalase activation in the hippocampus.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.23 no.2
• /
• pp.261-267
• /
• 1994

Parched mugwort tea was manufactured from mugwort (Artemisia asicatica nakai) leaves by traditional green tea preparation method. Volatile flavor compounds were collected by Tenax GC and they separated on DB-5 capillary column ($60m\;\times\;0.25mm$ i.d.) Fifty eight compounds were isolated and identified by GC-MS from the volatiles. Eleven compounds incucluding benzaldehyde, pinene, myrcene, cineole, 2-phrrolidinonoe, camphor, thujong, 1-acetylpiperidine, caryophyllene, coumarin, and farnesol among the compounds identified were considered as important compounds contributing mugwort-like flavor to the parched mugwort tea. The mixture of these eleven authentic compounds could reproduce aroma of mugwort leaves harvested in April. As results, the concentrations of these eleven flavor compounds in parched mugwort tea may indicate the strength of mugwort-like aroma of the tea.