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KMID : 1007520040130020156
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Food Science and Biotechnology
2004 Volume.13 No. 2 p.156 ~ p.161
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The Effects of Tea Manufacturing Methods on the Contents of Chemical Components and Antioxidative Activity in Tea Infusions
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Yasuda, Midori
Kondo, Michio/Sonda, Tamiyoshi/Takedomi, Kazumi/Eguchi, Syouhei/Eguchi, Ayumi
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Abstract
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The effects of tea manufacturing methods on the contents of chemical components and antioxidative activity in tea infusions were studied. Tea samples were manufactured by three different methods using the same fresh tea leaves that were plucked on the same date at th same place. The tea manufacturing methods in this study were the steamed method, the parched method of the conventional style, and new parched method of Eguchi style with high pressure in an airtight pan. The difference of manufacturing methods had hardly any effect on the content of minerals, amino acids and caffeine in infusions. However, the catechins in the tea manufactured by the parched method of the Eguchi style were at a higher level than those in tea leaves manufactured by the other methods. For the antioxidative activity, the tea manufactured by the parched method of the Eguchi style also had the highest activity. The tea tissues at their cross section were observed by a scanning electron microscope. As a result, the destruction of tea tissue was confirmed for the tea leaves manufactured by the parched method. These results could be due to a complete inactivation of polyphenol oxidase and the destruction of tea tissues by th manufacturing process at a high temperature in an airtight pan.
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