• Journal of Nutrition and Health
• /
• v.31 no.8
• /
• pp.1355-1364
• /
• 1998

This study was planned to investigate the effect of 40 plant ethanolic extracts on antioxidant activities in vitro. The total phenolics, $\beta$-carotene, $\alpha$-tocopherol and selenium contents were also determined . Antioxidant activities fo the ethanolic extracts(0.02%, w/w) in the soybean oil were measured both by determining the peroxide value (POV) during 35 days of storage at 4$0^{\circ}C$ in a forced draft air-incubator and by determining changes in conductivity at 11$0^{\circ}C$(Rancimat method.). Soybean oil without any additives was used as a control and that treated with 0.02% BHT was used as a positive control. Based on the POV determination, green tea extract was found to be the most effective in stabilizing soybean oil, then followed by long tea, which both of them showed higher antioxidant activities compared to the BHT treatment. The antioxidant activities of them showed higher antioxidant activities compared to the BHT treatment. the antioxidant activities of coffee, cinnamomi cortex, acanthopanacis cortex, black tea, orange peel , instant coffee, peony and crni fructus extracts were stronger compared to the control .By the Rancimat method, green tea leaf and oolong tea leaf, foxglove, acanthopanacis cortex and peony extracts. Compared to other extracts, green tea leaf, black tea leaf, foxglove, acanthopanacis cortex and peony extracts had stronger antioxidative effects in both the POV and Rancimat methods used in this study. ethanolic extracts which showed the stronger antioxidative effect also has the higher contents of total phenolics, $\beta$-carotene, and/or $\alpha$-tocopherol. The antioxidative effect of ethanolic extracts was found to be due to the combined effect of various antioxidants.

• Korean Journal of Food Science and Technology
• /
• v.13 no.4
• /
• pp.267-272
• /
• 1981

The qualities of ginseng leaf teas prepared by six different processing methods were evaluated to develop the leaf tea. The leaf tea prepared by fermentation at $30^{\circ}C$ showed the highest in the ratio of 30 min water extracts to the total extractable matters. This ratio was followed in decreasing order by the heat dried tea and the one fermented at $25^{\circ}C$. The yellow, orange and red color intensities of water extracts were the highest in the tea prepared by toasting method followed by teas fermented at $30^{\circ}C\:and\:25^{\circ}C$. The amount of saponins extracted with boiling water was the highest in the tea fermented at $30^{\circ}C$ among teas investigated. This tea was also most acceptable in sensory evaluation by the flavour profile method.

• The Korean Journal of Food And Nutrition
• /
• v.16 no.4
• /
• pp.365-371
• /
• 2003

This study was analyzed to the characteristics of the Lindera obtusiloba eaf teas by various manufacture methods. Moisture content was the highest in the tea processed by air dry method, and the lowest in the tea roasted after steaming. The contents of soluble solid was higher in the fermented tea than in the others, and the lowest in the roasted tea. The content of tannin was the higher in the roasted after steaming tea than in the others, and the lowest in the fermented tea. The content of vitamin C was the higher in the roasted tea than in the others, and the lower in the steamed tea. The mineral contents of leaf teas was orderly K, Na, Mn, Ca, Fe, Mg, and Zn. The roasted after steaming tea was estimated to the most excellent in the sensory evaluation of leaf teas.

• Food Science and Preservation
• /
• v.5 no.3
• /
• pp.262-269
• /
• 1998

In order to promote the applications of Korean loquat leaf as food, loquat leaf tea was manufactured and its physicochemical characteristics were examined. The contents of moisture, crude fat and ash of loquat leaf collected in the middle of February were lower than those collected in October. Mineral contents after 4 times of roasting loquat leaf between February and October were higher 39,916.8 ppm and 23,950.0 ppm of K, respectively. The contents of ascorbic acid(2.33%), free sugar(fructose 1.01%), tannin(1.63%) and caffein(113 mg%) were higher in October than those February. The chromaticity and absorbance of loquat leaf tea percolate were higher in 2 times of roasting but were lower 4 times of roasting in October than those in February. In free amino acid of its percolate and volatile component of 4 times of roasting leaf tea collected in October, DL-allohydroxylysine and nerolidol were higher, respectively.

• Korean journal of food and cookery science
• /
• v.26 no.5
• /
• pp.567-574
• /
• 2010

Pork patties were formulated with either steam-dried green tea power or freeze-dried raw tea leaf powder, and the quality characteristics of these products were monitored. Proximate analysis of tea powder contained 17.80~19.85%, 4.70~5.73%, and 5.60~5.77% (as is) crude protein, crude fat, and crude ash, respectively. There were no significance differences in pH among the samples. Chromaticity tended to decrease brightness ($L^*$) and redness ($a^*$), and there were significant differences in yellowness ($b^*$) as the added amount of tea power was increased. For texture, hardness increased as more green tea powder was added. Thiobarbituric acid reactive substances (TBARS) and volatile basic nitrogen (VBN) values increased after storage for 12 days, whereas samples formulated with green tea powder showed lower TBARS and VBN values compared to control groups. Sensory panelists showed preference for samples with green tea powder added compared to the control group.

• Applied Biological Chemistry
• /
• v.22 no.1
• /
• pp.51-57
• /
• 1979

The possibility of utilizing greet amount of by-product of ginseng (Panax ginseng C.A. meyer) plant-that is, production of ter from ginseng leaf, was studied and the results are summarized as follows: 1. Ginseng leaf contains more soluble matter than tea leaf (Thea sinensis) and the soluble matter is easily extracted by hot water. 2. Ginseng leaf has less tannin (2.2%) than yea leaf (7.89%). Therefore, it has less astringency than tea. 3. Vitamin C content of ginseng leaf is not compared with that of tea leaf. In fact, ginseng leaf contains Vitamin C $50{\sim}110$ times of tea leaf. 4. Ginseng leaf contains $5.7{\sim}8.5%$ glycoside (dammaranes) and the ratio of panaxadiol to panaxatriol is $0.54{\sim}0.75$ that is, panaxatriol contents is high. 5. For the acceptability of the product related with the soluble matter contents and color the method of extracting 2g of ginseng leaf product in 200ml of water for 3 minutes is recommended. 6. As a result of evaluating the flavor characteristics and effective components of the products, product D which is produced by the process of steaming, drying and roasting is considered to have the best quality.

• Food Science and Preservation
• /
• v.21 no.4
• /
• pp.549-559
• /
• 2014

This study investigated the hypoglycemic effects of mulberry leaf (M), green tea (G), and a mixture of mulberry leaf and green tea (MG) in rats with streptozotocin-induced diabetes. Male Sprague-Dawley rats were divided into the non-diabetic (N) and diabetic groups. The experimental animals were divided into four groups and fed the following for four weeks: a normal diet (N), the STZ+normal diet (STZ), the STZ+5% mulberry leaf (STZ-M), STZ+5% green tea (STZ-G), and the STZ+5% mixture of mulberry leaf and green tea (STZ-MG). The whole blood glucose level of the STZ-M, STZ-G and STZ-MG groups significantly decreased compared to the STZ group two weeks later. The serum glucose and fructosamine, and urine glucose levels in the STZ-M, STZ-G and STZ-MG groups were lower than in the STZ group. The levels of serum insulin were higher in the STZ-M, STZ-G and STZ-MG groups than in the STZ group. However, serum glucose, fructosamine and insulin levels, and urine glucose levels were not significantly different among the STZ-M, STZ-G and STZ-MG groups. These results indicate that mulberry leaf, green tea, and their mixture help prevent or attenuate the progression of diabetes in rats with STZ-induced diabetes.

• Journal of agriculture & life science
• /
• v.45 no.5
• /
• pp.1-8
• /
• 2011

In this study, 160 tea tree (Camellia sinensis L.) lines were classified by caffeine content using colorimetric methods. Among them, caffeine-rich lines (HR-78, HR-137, HR-82 and HR-123) and poor lines (HP-85, HP-88, HP-19, and HP-131) were selected. To know the difference in morphological and genetic characters between caffeine-rich and poor lines, we used leaf/shoot growth and RAPD methods. Cluster pattern of morphological characters (leaf width, leaf length, leaf area and shoot length) showed that shoot length was longer in caffein-rich lines than in -poor lines. In genetic analysis, amplified DNA bands having various sizes were detected in RAPD analysis where 30 random primers were used. However, the discriminated primer set that distinguish caffein-rich tree line from -poor lines was not found. These results can be used as the basic data to determine the morphological and genetic differences among caffein-rich and -poor lines.

• Journal of Korean Society of Forest Science
• /
• v.53 no.1
• /
• pp.37-43
• /
• 1981

This study was aimed at expanding the tea plant culture in Korea to further north, and the leaf-form and the cold resistance of the tea plants selected form 7 districts(around Korea) were investigated. 1. The length of tea leaf is 5.1cm to 8.4cm, the width of the leaf is 2.3cm to 3.6cm, but the area of tea leaf in Mt. Mudung is $26.88cm^2$ and that is the widest of all. 2. The tooth number of the tea leaf in 43 to 73 but the number of Mt. Borim is remarkably number of all. The tooth number is increased or decreased in proportion to the leaf width and to the leaf length. 3. The lateral vein number is generally 13 to 19. The vein number of Mt. Borim is especially number of all. That is also increased or decreased in proportion to the leaf width and to the leaf length. 4. In general, the number of leaf formation index is 2 to 3, and ablong. 5. In general, those which come upper lands are remarkably small in length and width of the tea leaf and those which come from level lands are large. 6. All kinds of tea plant which is growing in Korea, area, are the same as those imported from China : Thea sinensis Linne var. Bohea. 7. I supposed that the external form of tea plant has a little changed by geography or climate for many a long day, since the tea plant had been transplanted in Mt. Samsin. 8. In the treatment of low temperature and duration of vernalization of their plants, those selected from Mt. Mudung and Mt. Hwaun were the coldest resistance, those from Mt. Samsin and Mt. Borim were medium and those from Mt. Joge and Nursery were cold sensitive. 9. The critical temperature of the tea plant from Mt. Mudung, Mt, Hwaum, Mt, Samsin and Mt. Borim was about $-10^{\circ}C$, and that from Mt. Joga and Nursery was about $-5^{\circ}C$. The critical temperature of frost injury of all tea plants in this experiments was $-15^{\circ}C$. 10. In spite of increasing the vernalization time, the critical temperature was not effected, but the treatments over critical temperature were increased their frost injuries. Based on these results, the coldest resistance, Mt. Mudung tea plant, was considered expanding their culture to further north improvement yields of the tea plants in Korea.

• Journal of the Korea Furniture Society
• /
• v.21 no.4
• /
• pp.284-292
• /
• 2010

This research was carried out to examine the properties of fancy cherry veneer overlaid on the PF resin bonded Meranti plywood floor, which 2.5% green tea leaf powder was applied in the UV varnishes and the adhesives for scavenging the volatile organic compounds. The results were as follows: 1. The various properties of the treated samples, such as density, moisture content, thickness swelling, bending strength(MOR), adhesion shear strength, surface abrasion, curling, cyclic delamination test with boiling water, boiling property, cold-resistance and heat resistance, acid resistance and alkali resistance, and anti-contamination property showed no significant difference between the properties of the control samples. 2.5% green tea leaf powder treated floor gave a little better results than the control for surface scratch test. 2. In case of QUV and weathering test, no difference between the treated sample and control was found. 3. The floor was discolored by adding 10% green tea leaf powder to UV coating, and the floor was also discolored to light green during by the soaking test. The color of floor was not changed up to 5% addition level.