Total antioxidant content and polyphenol profile of a range of teas

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Total antioxidant content and polyphenol profile of a range of teas

 

Author: Wong, Wan Yee
Title: Total antioxidant content and polyphenol profile of a range of teas
Degree: M.Sc.
Year: 2013
Subject: Antioxidants.
Catechin.
Tea.
Hong Kong Polytechnic University -- Dissertations
Department: Dept. of Health Technology and Informatics
Pages: xiii, 97 leaves : ill. (chiefly col.) ; 30 cm.
Language: English
InnoPac Record: http://library.polyu.edu.hk/record=b2637233
URI: http://theses.lib.polyu.edu.hk/handle/200/7067
Abstract: Tea (Camellia sinensis) is the second most consumed beverage in the world. Green tea (unfermented), oolong tea (semi-fermented) and black tea (fermented) are major categories of tea that are differentiated by their process of production and composition. It is not only a pleasant, popular and sociable beverage but also has been reported a potential association with health benefits such as anti-oxidant, anti-carcinogenic, anti-atherosclerotic and neuroprotective activities. Most of the benefits are attributed to its polyphenolic flavonoids, catechins. The aims of this work are to study the level of total antioxidant content of green, oolong and black teas in vitro and to analysis their catechin profiles. Ten types of green, oolong and black teas were chosen and carried out the ferric reducing/antioxidant power (FRAP) assay to measure the total antioxidant power of teas and catechin analysis using high-performance liquid chromatography with tandem mass spectrometry (HPLC-MS/MS). It is found that all green teas have the highest antioxidant power compared with the others that agreed with previous studies. Catechin, epigallocatechin-3-gallate (EGCG) is reported its highest content among other analyzed catechins. Also, the highest content of EGCG has been shown in green teas. However, relatively high content of EGCG was found in some oolong teas that implied to an alternative of green teas. In addition, a linear relationship was shown between total antioxidant power and catechin content. This study provides more information on the level of total antioxidant power and catechin profiles in commercial tea bags and oolong teas might develop an alternative source of EGCG to green teas.

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