• Korean Journal Plant Pathology
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• v.11 no.4
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• pp.383-385
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• 1995

Occurrence of white scab of tea (CAmellia sinensis) showing numerous, small, circular, reddish or yellowish brown spots on young tea leaves was observed at a tea plantation of Boseung, Chonnam, from May to June in 1992-1994. At the late growth stages, the center of the spot became light gray. The causal fungus of the white scab was identified as Sphaceloma theae Kurosawa. Symptoms were produced 5∼6 days after inoculation by the artificial inoculation of s. theae conidia, which was similar to those on naturally infected leaves.

• The Korean Journal of Food And Nutrition
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• v.28 no.5
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• pp.766-773
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• 2015

This study analyzes the chemical composition of green tea, white tea, yellow tea, oolong tea and black tea with respect to extraction temperature and time. The optimum extraction conditions for these teas were determined by assessing the chemical composition of tea brewed at different temperature (50, 60, 70, $80^{\circ}C$) and extraction times (1, 3, 5, 10 minute). Catechins contents were the largest at 5 minutes and generally declined by 10 minutes. Green tea catechins contents were highest when brewed at $70^{\circ}C$ and besides other teas a change of the trend variation at 70 and $80^{\circ}C$. These temperatures did not extract theaflavins in green tea. Extract temperature and time did not significantly affect theaflavins content of white tea, yellow tea, and oolong tea. Black tea, however, was noticeably dependent on extract conditions, which were most effective at $70^{\circ}C$, brewed for 5 minutes. Caffeine content of green tea, yellow tea, and oolong tea was highest at 5 minutes, but temperature did not appear to affect the content. White tea and black tea caffeine content was highest when brewed at $70^{\circ}C$ for 5 minutes. Theobromine content of green tea, yellow tea, oolong tea, and black tea did not show major differences between the study times or temperature, though the content in white tea increased with higher temperatures when brewed for 5 minutes. The extraction of phenolic compounds increased until 5 minutes, and showed not further increase at 10 minutes. Antioxidant capacity of green tea, white tea, and yellow tea were maximized at $70^{\circ}C$ for 5 minutes or $80^{\circ}C$ for 3 minutes, while oolong and black tea were reached maximum antioxidants at $70^{\circ}C$ for 5 minutes. In general, to optimize the beneficial chemical content of brewed tea, a water temperature of $70^{\circ}C$ for 5 minutes is recommended.

• Food Science of Animal Resources
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• v.41 no.5
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• pp.840-854
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• 2021

The impact of green tea extract powder and rosemary extract powder, alone or in combination, on the quality characteristics of naturally cured pork sausages produced with white kimchi powder as a nitrate source was evaluated. Ground pork sausages were assigned to one of seven treatments: control (0.01% sodium nitrite and 0.05% sodium ascorbate), treatment 1 (0.3% white kimchi powder and 0.05% green tea extract powder), treatment 2 (0.3% white kimchi powder and 0.1% green tea extract powder), treatment 3 (0.3% white kimchi powder and 0.05% rosemary extract powder), treatment 4 (0.3% white kimchi powder and 0.1% rosemary extract powder), treatment 5 (0.3% white kimchi powder, 0.05% green tea extract powder, and 0.05% rosemary extract powder), and treatment 6 (0.3% celery juice powder, 0.05% green tea extract powder, and 0.05% rosemary extract powder). Naturally cured products had lower (p<0.05) cooking yield and residual nitrite content than control sausages. However, compared to the control, naturally cured products with white kimchi powder (treatments 1 to 5) showed similar the pH, oxidation-reduction potential, CIE L^* values, CIE a^* values, nitrosyl hemochrome content, total pigment content, and curing efficiency to the control. When the amount of green tea extract powder or rosemary extract powder was increased to 0.1% (treatments 2 and 4), lipid oxidation was reduced (p<0.05). These results indicate that green tea extract powder, rosemary extract powder, and white kimchi powder may provide an effective solution to replace synthetic nitrite and ascorbate used in traditionally cured products.

• Korean Journal of Food Science and Technology
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• v.54 no.2
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• pp.228-234
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• 2022

Various types of tea have been cultivated to obtain different flavors and enhance their functional properties. The objective of this study was to investigate the physicochemical properties of γ-aminobutyric acid (GABA) teas produced from commercial Korean green, white, and black teas. The concentration of total minerals was reduced in GABA green tea and GABA white tea but was improved in GABA black tea. The essential, non-essential, and total free amino acid contents were remarkably increased in the GABA teas. The amino acid GABA content was increased by 561.00 and 294.20 times in GABA white tea and GABA black tea, respectively. The antioxidant potential was not reduced, although the total polyphenol and total flavonoid contents decreased in GABA green tea and GABA black tea. The results indicated that the overall nutritional value of commercial green, white, and black teas could be improved by processing them into GABA teas.

• Food Science of Animal Resources
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• v.34 no.4
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• pp.403-407
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• 2014

Changes in Maillard reaction of pidan white were monitored with $A_{294}$, fluorescence intensity, and browning intensity during pickling in the absence and presence of Chinese black tea extract (Camellia sinensis) at levels of 2% and 5% together with 0.2% $ZnCl_2$ or 0.2% $CaCl_2$ up to 3 wk, followed by ageing for another 3 wk. Browning intensity and $A_{294}$ of pidan white increased with increasing pickling/ageing, while fluorescence intensity decreased during ageing (p<0.05), irrespective of treatments. At wk 6, pidan white treated with 0.2% $ZnCl_2$ and 0.2% $CaCl_2$ showed slightly higher browning intensity, fluorescence intensity and $A_{294}$ than those treated with divalents together with Chinese black tea (p<0.05). Free amino group and sugar contents showed continuous decrease during pickling and ageing irrespective of tea and cations used. However, pidan treated without Chinese black tea extract showed significantly lower free amino group and sugar during the ageing of 6 wk (p<0.05). Thus, Chinese black tea extract had an inhibitory effect on the Maillard reaction during ageing of pidan white.

• Korean journal of food and cookery science
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• v.15 no.4
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• pp.395-400
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• 1999

This study was to investigate the effects of green tea powder addition on the quality of white bread. Initial pasting temperature on amylograph increased and peak and final viscosity decreased with the addition of green tea powder. The lightness values of bread crust decreased and lightness and redness value of bread crumb was not affected, but b values decreased with the increase of green tea powder contents. The volume was significantly reduced with addition of green tea powder up to 5.0% level, compared to that of control. The addition of green tea powder at 2.5% was not affected in most of texture parameters(hardness, springiness, cohesiveness, gumminess and chewiness). But, 10% green tea powder addition to the bread increased significantly hardness, gumminess and chewiness. As results of sensory evaluation, the bread containing 2.5% green tea powder had the highest score in appearance, color, flavor, taste, texture, and overall acceptance. Concludingly, in terms of overall properties, the addition of 2.5% green tea powder to white bread showed the best result.

• Applied Microscopy
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• v.41 no.3
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• pp.197-204
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• 2011

To investigate the alleviative effect of white tea water extract on the inflammation and skin barrier damage, skin aging animal model was produced by the irradiation of UVB to the backs of hairless mice for 12 weeks. And then experimental materials were applied topically for 4 weeks. At the 28th day of experiment, positive control (PC, 0.01% retinoic acid treatment) and experimental groups (E1, 1% white tea water extract treatment; E2, 2% white tea water extract treatment) had significantly (p<0.001) lower values of both skin erythema index and transepidermal water loss (TEWL) than the control (C, saline treatment) group. The appearance of mast cell and the degree of its degranulation in dermal and subcutaneous layers were remarkably reduced in E1 and E2 groups compared to the C group. It is found that white tea water extract is effective in skin barrier damage and inflammation in hairless mouse.

• Preventive Nutrition and Food Science
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• v.8 no.4
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• pp.377-382
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• 2003

This study investigated the effects of green tea on the muscle antioxidative defense system in the white & red gastrocnemius muscles of rats after aerobic exercise. Male Sprague-Dawley rats weighing 150 10 g were randomly assigned to a control group, non-exercise with green tea group (G group), and exercise training group. The exercise training group was then further classified as the training (T) group and training with green tea (TG) group, the latter of which was supplemented with green tea in the drinking water during the experimental period. The rats in the exercise training groups (T and TG) were subjected to aerobic exercise on a treadmill 30 min/day at a speed of 28 m/min (7% incline) 5 days/week, while the other groups (control and G group) were cage confined for 4 weeks. Thereafter, the rats were sacrificed with an injected overdose of pentobarbital just after running. In the white muscle, the xanthine oxidase (XOD) activities were 71 % higher in the T group compared to control group, whereas the TG group had the same activity as the control group. The XOD activities in the red gastrocnemius muscle exhibited the same tendency as in the white muscle. The superoxide dismutase (SOD) activity in the white muscle was lower in the T group compared with the control group, yet significantly higher in the TG group compared with the T group. The SOD activities in the red gastrocnemius muscle exhibited the same tendency as in the white gastrocnemius muscle. The glutathione peroxidase (GSHpx) activities in the white & red gastrocnemius muscles were 43 % lower in the T group compared with the control group, yet the activities in the TG group remained at control levels. The glutathione S-transferase (GST) activity in the white muscle was not significantly different among any of the three groups, but in the red gastrocnemius muscle, the TG group had the same activity as in the control group. The thiobarbituric acid reactive substance (TBARS) contents in the white & red gastrocnemius muscles were higher in the T group than in the control but the control and TG groups had the same concentrations of TBARS. In conclusion, the supplementation of green tea in rats subjected to aerobic exercise was found to reduce the peroxidation of muscle lipids by enhancing the antioxidative defense mechanism.

• Toxicological Research
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• v.30 no.4
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• pp.283-289
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• 2014

Tea flavonoids and polyphenols are well known for their extraordinary antioxidant activity which is considered important for anti-aging processes in animals. This study evaluated the anti-wrinkle effects of three different kinds of tea (Camellia sinensis) water extracts (CSWEs) including green, white, and black teas using a photoaged hairless mouse model. Data showed that the CSWE-treatment greatly improved skin conditions of mice suffering from UVB-induced photoaging, based on the parameters including the skin erythema index, moisture capacity, and transepidermal water loss. In addition, the wrinkle measurement and image analysis of skin replicas indicated that CSWEs remarkably inhibited wrinkle formation. In histological examination, the CSWE-treated mice exhibited diminished epidermal thickness and increased collagen and elastic fiber content, key signatures for skin restoration. Furthermore, the reduced expression of MMP-3, a collagen-degradative enzyme, was observed in the skin of CSWE-treated animals. Interestingly, comparative data between green, white, and black tea indicated that the anti-wrinkle activity of white tea and black tea is equally greater than that of green tea. Taken together, these data clearly demonstrated that CSWEs could be used as an effective anti-wrinkle agent in photoaged animal skin, implying their extended uses in therapeutics.

• Food Science and Preservation
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• v.17 no.3
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• pp.328-333
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• 2010

The effects of green tea on the physicochemical properties of eggs were investigated. One-hundred-and-fifty Isa Brown hens (27 weeks of age) were studied over 10 weeks. Green tea was added to the diet at levels of 4% and 8% w/w. The contents of Ca, K, P, Fe and Mg in eggs increased upon dietary supplementation with green tea powder, and were higher in the yolk than in the white, with the exception of Mg. The increase was greatest for Ca, from 41.0 mg% to 119.8 mg%, in egg white. For Fe, an increase from 3.7 mg% to 12.6 mg% was apparent in egg yolk. When hens consumed the green tea-supplemented diets, average egg weight decreased from 68.8 g to 64.4 g, but the total cholesterol content of egg yolk did not significantly change (control value: 1,899.1 mg% test value: 2,011.3 mg%). In sensory evaluation tests, egg white was similar in terms of astringency and grayness regardless of diet, and egg yolk was yellow-to-orange in color, and rated as fishy or slightly fishy, when green tea diets were administered. Such diets reduced pH values in all of the white, yolk, and white/yolk combination groups. The major fatty acids of egg yolk, constituting more than 90% of total fatty acids, were palmitic, stearic, oleic, and linoleic acid. Green tea diets reduced the saturated fatty acid level from 32.0% to 27.4% of total fatty acids, and unsaturated fatty acid levels increased from 68.0% to 72.6% in egg yolk.