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Int. J. Mol. Sci. 2007, 8(12), 1196-1205; doi:10.3390/i8121196

Polyphenolic Profile and Antioxidant Activities of Oolong Tea Infusion under Various Steeping Conditions

1, 1, 1,*  and 2
1 South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650; P. R. China 2 Department of Food Science & Human Nutrition, Clemson University, SC 29634, USA
* Author to whom correspondence should be addressed.
Received: 15 October 2007 / Revised: 16 November 2006 / Accepted: 19 November 2006 / Published: 28 November 2007
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The phenolic profile and antioxidant activities of oolong tea extract wereinvestigated after tea was steeped in 90 or 100 oC water for 3 or 10 min. The extractionyield increased with increasing temperature and extended steeping time. However, highertemperature and longer time (100 oC water for 10 min) led to loss of phenolics. Theaqueous extract of oolong tea (AEOT) at 100 oC for 3 min exhibited the strongestantioxidant activity. The major polyphenolic components of the AEOT were identified as(-)-epigallocatechin (EGC), (-)-epigallocatechin gallate (EGCG) and (-)-epicatechin-3-gallate (ECG). The two major catechins (EGC and EGCG) in the tea infusion contributedsignificantly to the investigated antioxidant activities [i.e., the 2,2-diphenyl-2-picrylhydrazyl hydrate (DPPH) radical scavenging and superoxide radical scavengingactivities] with high correlation values in r = 0.9486 and 0.9327 for the EGC and r =0.9592 and 0.8718 for the EGCG, respectively.
Keywords: Oolong tea; Infusion; Antioxidant activity; Phenolics Oolong tea; Infusion; Antioxidant activity; Phenolics
This is an open access article distributed under the Creative Commons Attribution License (CC BY) which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Su, X.; Duan, J.; Jiang, Y.; Duan, X.; Chen, F. Polyphenolic Profile and Antioxidant Activities of Oolong Tea Infusion under Various Steeping Conditions. Int. J. Mol. Sci. 2007, 8, 1196-1205.

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