• Journal of Nutrition and Health
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• v.29 no.8
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• pp.861-866
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• 1996

Tannins in plant foods and beverages may produce antinutritional or toxic effects although some proteins with high affinity for tannins seem to function as defense mechanism to tannin toxicity. Our objectives were to investigate of tea tannins, iron and protein and to evaluate the role of proteins in tannin effects on iron solubility. Iron solubility in vitro was measured using tea with and without proteins. Mixtures of tea, protein in varying concentrations(either gelatin or bovine serum albumin), and iron(eithe 10 or 50ug/mL) were prepared. Controls contained water in place of tea. Iron bioavailability was assessed by measuring iron solubility in the simulated gastric condition with pepsin digestion. Bound iron was removed by centrifugation and soluble in tea alone. When iron concentratin was 10ug/mL, addition of small amounts of protein to tea dramatically reduced iron solubility, but solubility of iron increased in the tea mixturea as the concentration of protein was increased. The percnetage of iron that precipitated was much greater at 10ug Fe/mL than the values at 50ug Fe/mL suggesting that the iron binding sites on the tea-protein complex was saturated. These results suggest that interactions of iron with tea tannins are influenced by the concentratins of protein and iron.

• Korean journal of food and cookery science
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• v.23 no.6
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• pp.954-960
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• 2007

The study was designed to determine optimum extraction conditions, by the factorial design of 3 variables and 3 levels using an a RSM program. To determine the optimal conditions for the extraction of black tea with chamomile, the experimental design was applied. The independent factors were the extraction temperature ($60^{\circ}C$, $80^{\circ}C$, $100^{\circ}C$), extraction time (2 min, 4 min, 6 min), and chamomile addition (0.3%, 1.0%, 1.7%). By the RSM (response surface methodology) analysis of the black tea with chamomile extraction, we found that the extraction temperature greatly affected the extraction yield, brix, pH, and reducing sugar, caffeine, theobromine and theophillin contents. The optimum extraction time, temperature, and chamomile content were 4 min, $90^{\circ}C$, and $1.6{\sim}1.7%$, respectively.

• Journal of the Korean Society of Food Science and Nutrition
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• v.24 no.2
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• pp.299-304
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• 1995

Antioxidative effect of tea extracts from green tea(steamed, roasted), oolong tea and black tea was investigated. Antioxidative activities of the crude catechin fraction were the most effective in oolong tea which contained the highest level of (-)-epigallocatechin gallate(EGCg). The water-soluble fraction obtained from oolong tea exhibited binding with more ferrous than copper ions. It showed a synergistic effect when used with an antioxidant such as BHT(0.5mg) and $\alpha$-tocopherol(2mg). Especially, this synergistic effect was exhibited more with BHT than with $\alpha$-tocopherol. Also steamed green tea, roasted green tea and oolong tea showed remarkable free radical scavenging action. The SC50(the concentration of a water-soluble fraction which is required to scavenge 50% of 100$\mu$M 1, 1-diphenyl-2-picryl hydrazyl radicals) of steamed and roasted green tea, oolong tea and black tea extracts were 11.3$\mu\textrm{g}$/ml, 11.4$\mu\textrm{g}$/ml, 12.7 $\mu\textrm{g}$/ml and 14.9$\mu\textrm{g}$/ml, respectively. It is assumed that the antioxidative activity of tea extracts is due to inhibition of peroxidation free radical scavenging and binding action of ferrous ions by mainly tea polyphenol compounds.

• Journal of the Korean Society of Food Science and Nutrition
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• v.24 no.1
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• pp.160-168
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• 1995

Desmutagenicities against 2-amino-1-methyl-6-phenylimidazo[4, 5-b] pyridine(PhIP) and 2-amino-3, 8-dimethylimidazo[4, 5-f]quinoxaline(MelQx) of tea extracts (steamed green tea, roasted green tea, oolong tea and black tea) were investigated. All the fractions obtained from tea extracts showed strong desmutagenic activity against PhIP and MeIQx toward S. typhimurium TA 98 in the presence of the S-9 mix. The crude catechin fraction exhibited the strongest desmutagenic activity. Among these tea extracts, black tea especially exhibited the strongest desmutagenic activity and the activity was 70.9~91.0% against PhIP and 92.2~98.8% against MelQx at a concentration(0.5~1.0mg/plate) for drinking. The activity of authentic catechins of (-)-EGC, (-)-EGCg, (-)-ECg and (-)-EC were 79.5%, 60.2%, 46.1% and 43.5% against PhIP, and were 52.3%, 11.6%, 8.2% and 22.1% against MelQx by addition of 1.0mg/plate, respectively. The desmutagenic activity was supposedly due to the (-)-EGCg, (-)-EGC and (-)-EC in tea polyphenols, and the browning materials. The desmutagenicity was stronger when mutagens were preincubated with S-9 mix after reaciton with black tea extracts than when preincubated with them after reaction with S-9 mix. The desmutagenicity of tea extracts was rather expressed by reacting directly with mutagens than by deactivating the activated forms of mutagens.

• Journal of Fashion Business
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• v.23 no.1
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• pp.64-73
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• 2019

The objective of this study was to investigate dyeing characteristics of silk, cotton and rayon fabrics using dyeing solution extracted from different varieties of tea. Comparative results of CIE Lab values of 360 pieces of dyed fabrics were studied to quantify the effects of dye concentrations (100%, 150%, and 200%) and mordants (Fe, Cu, Sn, Al). In addition, the color difference values (${\Delta}E$) of the dyed and mordanted fabrics were evaluated. The results of the study were as follows: First, among all of the 360 pieces of silk, cotton and rayon fabrics, the best dyeing effects was observed on silk fabrics. Second, the dyeing effect of the eight different types of tealeaves belonging to green tea, oolong tea, black tea, and dark tea tended to enhance as the degree of fermentation increased. Third, when the fabrics were mordanted with Fe, Cu, Sn, Al mordants, various colors such as brown, brownish red, brownish yellow, gray, and reddish brown were obtained.

• Journal of the Korean Society of Food Culture
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• v.22 no.4
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• pp.449-453
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• 2007

Using green tea(GT), oolong tea(OT), black tea(BT) and green tea bag(GTB) out of tea products in market, this study quantified polyphenol and catechins as anti-oxidant substances and analyzed their respective anti-oxidant capacities. As a result, more epigallocathechin(EGC) was found in GT and GTB as well as caffein(CAF) in GT and BT. GT contained more epigallocathechin gallate(EGCG) than other tea types. Both FRAP and ORAC, as two methods of analyzing anti-oxidant capacities, showed that GTB had highest anti-oxidant capacities, while OT had lowest of all. By brand, it was found that all the 3 brands of GT had similarly high anti-oxidant capacities, but there were differences in the anti-oxidant activities of GTB and BT depending on brand. Out of catechin components, it was found that epicatechin(EC), epicathechin gallate(ECG) and EGCG were major components affecting anti-oxidant capacities.

• Journal of the Korean Society of Food Culture
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• v.24 no.3
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• pp.308-314
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• 2009

In this study, we examined the composition of catechins, theaflavins and alkaloids in leaves during processing to fermented black tea, which is produced by withering, roll breaking, and fermentation of Korean Yabukida tea plant. In addition, we determined the optimal conditions for the production of fermented black tea. The average moisture content in fresh leaves was 70.85%, which dropped to 3.07% in fermented black tea at the last stage of production. When the leaves were analyzed by HPLC, seven types of catechins, four types of theaflavins and three types of alkaloids were identified. The levels of catechins, theaflavins, and alkaloids were then evaluated after being processed into fermented tea. From these experiments, we found that the level of theaflavins, which determines the property of the tea, increased during fermentation. This effect resulted from the change in EGCG, ECG, EGC, EC during the process of fermentation. We also found that the maximal amount of theaflavins was created after 1-2 hours of fermentation. Thus, our results imply that the best condition for producing fermented black tea would be to ferment for 1-2 hours.

• Journal of the Korean Society of Food Science and Nutrition
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• v.23 no.5
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• pp.784-791
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• 1994

This study was to investigate the cadmium removal effect of Korean green tea, black tea and oolong tea beverage on Cd administered rat, tissues and their excretions. Male Sprague-Dawley rats weighing 143±3.2g were divided into control and experimental groups. The control group were fed standard diet without cadmium . The experimental groups, which were fed standard diet containing 40 ppm Cd, were divided into 4 subgroups again , which were the groups given distilled water (CD group), 5% black tea (BT group), oolong tea (OT group ) and green tea (GT group), respectively. Five days before to sacrifice the rats, all 4 cadmium fed groups were supplied 1 ml of water with 600ppm Cd and control group were fed 1 ml of distilled water without Cd under the same dietary condition. After that, their excretion were collected separately for 3 days. In rat liver and kidney, accmulation of cadmium in 4 Cd administered groups were more than in control group and that of GT group was significantly less than CD group. In bone , also, accumulation of cadmium in 4 Cd administered groups was more than in control group and that of GT, OT,BT groups were much less than that of CD group. GT group was excreted more Cd in urine than Cd group. In feces, 3 tea feeding groups (BT, OT, GT group) were excreted Cd 1.7, 2.1, 2.4 times more than that of the CD group, respectively. We conclude that cadmium accumulations of GT feeding group in rat's liver, kidney and bone were much less than CD group , and the absorption and retention rate of GT group was significantly lower than CD group.

• Journal of the Korean Society of Food Culture
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• v.2 no.2
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• pp.133-147
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• 1987

The sensory quality characteristics of 7 different types of Korean traditional tea products were analyzed. For the standardization of sensory testing condition, the optimum drinking temperature were measured with 50 students, and all the samples tested were found to fall in the range of $60-70^{\circ}C$. The optimum concentrations of tea for drinking were generally met with the amount recommended by the producer. A total of 45 sensory describing terms expressing the taste, odor, and mouthfeel were collected. Using the sensory describing terms as the character notes, flavor profile analysis was made for each tea product with 8 members of trained panel. The differences in quality characteristics of 29 test samples were evaluated and shown in the chart constructed by the quantitative descriptive analysis method.

• Journal of Food Hygiene and Safety
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• v.16 no.4
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• pp.295-299
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• 2001

This study was performed to survey and evaluate the contents of caffeine in commercial palatability foods by HPLC. The contents of caffeine in commercial palatability foods were 9.0~49.2 mg in black tea, 35.9~141.4 mg in coffee, 12.4~48.0 mg in green tea, 7.1 ~16.5 mg in brown rice green tea, 22.8 mg in cocoa tea, 10.3~25.0 mg in cola and 10.0~48.2 mg in ice bar(coffee) respectively. The contents of caffeine extracted from black tea, coffee(roasted beans) and green tea were rapidly increased for five minutes from the extraction initiation, and were not nearly changed after ten minutes. Moreover, the caffeine contents were increased until 10$0^{\circ}C$ of extraction temperature.