• Korean Journal of Food Science and Technology
• /
• v.47 no.4
• /
• pp.419-424
• /
• 2015

The objective of this study was to investigate the physicochemical and antioxidant properties of a variety of commonly consumed commercial green tea. Green tea samples with the same commercial name produced at different regions were analyzed. High-grade tea samples showed higher values of lightness (L) and greenness (-a). Additionally, compared to other varieties of teas, high-grade tea samples showed higher levels of catechin, gallocatechin gallate (GCg), epicatechin gallate (ECg), theanine, and methylxanthines and a lower level of epigallocatechin (EGC). The antioxidant activity of green tea was also investigated using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) radical assays. High-grade teas were observed to have higher antioxidant activities. The results of this study indicate that the catechin content, such as EGCg, GCg, and ECg levels, was found to positively influence the total antioxidant activity of green tea.

• Journal of Food Hygiene and Safety
• /
• v.11 no.2
• /
• pp.77-82
• /
• 1996

Green tea catechins(GTC) were studied for its inhibitory effect on human platelet aggregation in vitro, for its antithrombotic effect in mice in viro, and bleeding and clotting time in rats. The catechins were isolated and purified from green tea, which were composed of (-)-epigallocatechin gallate, (-)-epigallocatechin, (-)epicatechin gallate and (-)-epicatechin, GTC produced a potent inhibition of human platelet aggregation in a dose-dependent manner against the stimulants such as ADP, collagen, epinephrine and ristocetin n vitro. GTC also prevented death due to the formation of pulmonary thrombosis by platelet aggregates in mice in a dose-de-pendent manner in viro. GTC increased the bleeding time, whole blood clotting time and plasma clotting time in rats, too. These results suggest that GTC is a promising antithrombotic agent.

• Land and Housing Review
• /
• v.10 no.2
• /
• pp.45-51
• /
• 2019

The purpose of this study was to examine the performance of formaldehyde removal from building materials using catechin contained in ginkgo leaf. A small chamber method was used to set up one control group and three experimental groups. As a result, it showed a reduction of formaldehyde from at least 73.5% to 77% when it was increased by 0.4g compared to the control (0g). In addition, it was confirmed by linear regression analysis that the amount of ginkgo leaf and the amount of formaldehyde emission were negatively correlated. Therefore, it was confirmed that the amount of formaldehyde emission was affected by ginkgo leaf.

• Journal of Life Science
• /
• v.27 no.4
• /
• pp.476-481
• /
• 2017

Polyphenols are secondary metabolites produced by higher plants and have been used as antiallergic, anticancer, antihypertensive, antiinflammatory, antimicrobial and antioxidant agents. They are generally divided into flavonoids and non-flavonoids. The antimicrobial activity of flavonoids are stronger than that of non-flavonoids. The skeleton structures of flavonoids possessing antimicrobial activity are chalcone, flavan-3-ol (catechin), flavanone, flavone, flavonol and proanthocyanidin. The flavonols are shown antibacterial activity against several gram-positive bacteria (Actinomyces naeslundii, Lactobacillus acidophilus and Staphylococcus aureus) and gram-negative bacteria (Fusobacterium nucleatum, Porphyromonas gingivalis, Prevotella melaninogenica and Prevotella oralis). Among of non-flavonoids, caffeic acids, ferulic acids and gallic acids showed antimicrobial activity against gram-positive (Listeria monocytogenes and S. aureus) and gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa). These are found to be more efficient against the E. coli, L. monocytogenes, P. aeruginosa and S. aureus than antibiotics such as gentamicin and streptomycin. The kaempferol and quercetin showed synergistic effect with ciprofloxacin and rifampicin against S. aureus and methicillin resistant S. aureus (MRSA). Epigallocatechin gallate (EGCG) acts synergistically with various ${\beta}-lactam$ antibiotics against MRSA. In particular, the epicatechin, epigallocatechin (EGC), EGCG and gallocatechin gallate from Korean green tea has antibacterial activity against MRSA clinical isolates and the combination of tea polyphenols and oxacillin was synergistic for all the clinical MRSA isolates.

• Food Science and Preservation
• /
• v.15 no.4
• /
• pp.576-581
• /
• 2008

The chemical components of the wild vegetables Solidago virgaurea spp. gigantea, Aster glehni var. hondoensis, and Aruncus dioicus var. kamtschaticus grown on Ulleung island, Korea were investigated. In dried powders of these three wild vegetables, the contents of moisture, crude protein, crude lipid, crude fiber, and crude ash were 3.77-5.72%, 15-29%, 3.50-6.68%, 4.00-6.01%, and 8.70-10.54%, respectively. There were differences in the levels and nature of organic acids in the vegetables; the major organic acids were succinic acid, citric acid, and malonic acid. The major free amino acids in the vegetables were glutamic acid, aspartic acid, arginine, and phenylalanine. Riboflavin contents were 90 mg% in Aruncus dioicus var. kamtschaticus and $2{\sim}3$ mg% in the other vegetables. The thiamin contents were 113 mg% in Aster glehni var. hondoensis, 85 mg% in Aruncus dioicus var. kamtschaticus, and 71 mg% in Solidago virgaurea spp. gigantea. The major fatty acids in the three vegetables were linolenic acid, linoleic acid, and palmitic acid; 60% of total fatty acid was linolenic acid. Catechins were present at 5.37 mg% in Aruncus dioicus var. kamtschaticus, 2.46 mg% in Solidago virgaurea spp. gigantea, 1.29 mg% in Aster glehni var. hondoensis.(-) ECC was detected in only Aruncus dioicus var. kamtschaticus. The contents of Ca, P, and Na in the three vegetables were higher than the contents of other minerals.

• Food Science and Preservation
• /
• v.12 no.6
• /
• pp.600-607
• /
• 2005

This study was conducted to prepare high quality grape seed oils by solvent extraction and chemical refining process. Additionally, quantitative analysis of several functional components in grope seed was carried out to compare quality characteristics of grape seeds from grapes grown by conventional and organic agricultural practices. There are no significant differences in several functional constituents of grape seeds between conventionally cultivated- and organically cultivated-grapes, although some functional compositions of grape seeds are different between two cultivation methods. The dried grape seed was pretreated with roasting heating for 5 min, milled and then extracted twice with n-hexane under reflux at $50^{\circ}C$ for overnight, followed by filtration and evaporation. The crude grape seed oil was successively purified by degumming with $0.1\%\;H_3PO_4$, deaciding with $20\%\;NaOH$, and then decoloring and deodorization by a steam distillation, and thereby producing purified grape seed oil(yield: $5.0\%/dried$ grape seed). Physicochemical characteristics of the purified grape seed oil were comparable to those of the imported grape seed oils.

• Journal of Food Hygiene and Safety
• /
• v.11 no.2
• /
• pp.83-87
• /
• 1996

The objective of this study is to investigate the direct effects of green tea catechins(GTC) on vascular smooth muscle tension and 45Ca2+ Uptake in rat aorta. The methods used in this study are isometric tension measurements using physiograph, Lanthanum method for 45Ca2+(2 uCi/ml) uptake measurement in rat aorta. GTC modified tension induced by 40 mM KCl or 1 uM norepinephrine in rat aorta. Low concentrations of GTC(<0.5mg/ml) increased tension by 40 mM KCl or 1 uM norepinephrine, individually. However, high conecentration of GTC(>0.5 mg/ml) inhibiited tension by 40 mM KCl or 1 uM norepinephrine, individually. GTC increased 45Ca uptake induced by 40 mM KCl in a dose-dependent manner. From these results, GTC has the dual actions in vascular smooth muscle in vitro. Low concentrations of GTC augments tension by K or norepinephrine. However, high concentrations of GTC inhibits tension by K or norepinephrine GTC may have Ca2+ channel activation, action, which may result in unphysiological vasodilation by Ca2+ overload in vascular smooth muscle.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.38 no.1
• /
• pp.83-88
• /
• 2009

After storing green tea powder for three months at three different temperatures (-20, 4, and $20^{\circ}C$) with three different relative humidities (RHs) (23, 69, and 81%), the chemical quality was evaluated with green tea, which was prepared by soaking 1.5 g of the powder into 100 mL of distilled water at $70^{\circ}C$ for 5 min. Total phenolic contents, total flavanol contents, and ascorbic acid contents of green tea powder stored at $4^{\circ}C$ with 23% RH changed from 267.5, 49.4, and 24.2 mg/g to 287.1, 44.9, and 36.9 mg/g, respectively, compared to the powder before storage. EGC and EGCG, the main catechins of green tea, also changed from 16.9 and 27.3 mg/g to 24.3 and 36.5, g/g, respectively, after storage for 3 months at $4^{\circ}C$ with 23% RH. However, when the green tea powder was stored at -20 or $20^{\cric}C$ with higher RH such as 69 and 81%, the chemical compounds were significantly decreased. The results indicate that temperature and RH are important during storage of green tea powder, and low RH and refrigerated condition ($-4^{\cric}C$) are preferable to increase or preserve the chemical compounds of the tea.

• Journal of the East Asian Society of Dietary Life
• /
• v.17 no.3
• /
• pp.409-416
• /
• 2007

This study investigated changes in the catechin and alkaloid contents of Bosung green tea during different manufacturing processes and storage periods, using HPLC and UV-VIS spectrophotometer analysis. For changes in the catechin and alkaloid contents by roasting technique, we found that EGCG, CG and GCG decreased just slightly by processes performed before roasting, rather than after roasting. In addition, theobromine, caffeine, and ECG changed minimally throughout all the processes. For changes in the catechin and purine alkaloid contents of the green tea leaves during storage, EGCG, ECG, and CAF decreased considerably in the green tea stored at temperatures of $5^{\circ}C$ and $25^{\circ}C$, and they decreased by $20{\sim}30%$ after storage for 1 year. However, a quantitative difference was hardly observed in the catechin and alkaloid contents regardless of storage temperature.

• Journal of Food Hygiene and Safety
• /
• v.17 no.3
• /
• pp.117-123
• /
• 2002

The five main green tea catechin components such as (+)-catechin, (-)-epicatechin, (-)-epigallocatechin, (-)-epicatechin gallate, and (-)-epigallocatechin gallate were analyzed quantitatively from commercial green tea by HPLC. Amounts of catechins decreased in the following order : (+)-catechin > (-)-epigallocatechin gallate >(-)-epigallocatechin >(-)-epicatechin >(-)-epicatechin gallate. In this study, the stability of the following green tea catechins to pH in the range from 3 to 11 was studied using of ultraviolet spectroscopy : (+)-catechin, (-)-epicatechin, (-)-epicatechin gallate, and (-)-epigallocatechin gallate. This study demonstrated that green tea catechins were not stable at high pH and that the pH-, and time-dependent spectral alternatives were not reversible In conclusion, low pH is important to maintain the efficient utilization of green tea catechins.