Antioxidant Properties of Water Extracts From Parching Green Tea

Abstract

Cold and hot water extracts (2, 6 and 10%) were prepared from parching green tea and its antioxidant properties studied and potential antioxidant components determined. Yields of hot water extracts (17.53-28.63%) were significantly higher than those of cold water extracts (13.34-16.14%). The half maximal effective concentration (EC(50)) values in antioxidant activity and reducing power were 2.17-2.75 and 0.22-0.30 mg/mL, respectively. Scavenging abilities on 1,1-diphenyl-2-picrylhydrazyl radicals were comparable. EC(50) values in scavenging ability on hydroxyl radicals and chelating ability on ferrous ions were 3.31-4.54 and 1.63-3.09 mg/mL, respectively. Contents of total phenols were 220.52-339.83 mg/g whereas those of total catechins in cold and hot water extracts were 130.22-146.28 mg/g and 136.40-191.33 mg/g, respectively. Based on the results obtained, hot water extracts were more effective in antioxidant activity, reducing power and scavenging ability on hydroxyl radicals but less effective in chelating ability on ferrous ions. PRACTICAL APPLICATIONS Tea is one of popular drinks in the world. The consumption of green tea is especially popular in Asia, mainly for its health benefits. Parched tea is a Chinese style green tea, which is different from the Japanese style steamed tea. Recently, the tea prepared by brewing tea leaves in cold water has become a new choice in Taiwan in addition to traditionally hot water-brewed tea. Results from this research, the cold and hot water extracts of green tea are good antioxidant. Besides, green tea is also reported to reduce serum cholesterol levels and inhibit hypertension, mutagenesis, and tumourigenesis in several experiments in vitro and in vivo. Therefore, the extract of green tea has the potential to be developed into new health foods, and the cold brewing would be a new alternative way to make a tea

Effects of Water Solutions on Extracting Green Tea Leaves

“…Instead of a brewing process [7, 31], green tea solutions were prepared using tap water and distilled water at 25°C. The former was taken from the suburban area of the City of Greater Taichung, Taiwan.…”

Effect of Different Brewing Methods on Quality of Green Tea

“…However, the effectiveness of cold and hot brewed tea infusions in antioxidant activity, reducing power, scavenging ability and chelating ability was found to be comparable (Lin et al 2008;2010). However, the effectiveness of cold and hot brewed tea infusions in antioxidant activity, reducing power, scavenging ability and chelating ability was found to be comparable (Lin et al 2008;2010).…”

“…Tea infusions in this research were prepared following the methods used in Lin et al (2008;2010). Generally, the brewing ratio of tea leaves to boiling water used in Taiwan is 2%, i.e., 3 g of tea leaves for 150 mL of boiling water (Yang et al 2007).…”

“…Many studies have shown that polyphenols extracted from green tea leaves are good antioxidants against lipid peroxidation in biological systems (Guo et al 1996), and against tumorigenesis and DNA damage (Jankun et al 1997;Anderson et al 2001). Besides, antioxidant properties of the cold water extracts from steamed green tea and parched green tea had been studied (Lin et al 2008(Lin et al , 2010. Besides, antioxidant properties of the cold water extracts from steamed green tea and parched green tea had been studied (Lin et al 2008(Lin et al , 2010.…”

The role of antioxidant versus pro‐oxidant effects of green tea polyphenols in cancer prevention

“…The extraction of green tea polyphenols into tea is both time‐ and temperature‐dependent 3, 4. Tea preparation is important, as hot water preparation causes tea to be better at scavenging oxidative radicals than cold water preparations 7, which is likely due to greater extraction of polyphenols. Green tea polyphenols can act as pro‐oxidants by generating hydrogen peroxide.…”