18E-27 |
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H. CHEN and C.-T. Ho. Dept. of Food Science, Rutgers, The State Univ. of New Jersey, 65 dudley road, New Brunswick, NJ 08901 Tea (Camellia sinesis) is one of the most widely consumed beverages in the world. The beneficial effects of tea are generally considered to be associated with its high content of polyphenolic compounds. It is well known that tea polyphenols possess antioxidant properties and may help lower risk of certain cancers and coronary heart disease. Thus, determination of Total Polyphenol Content (TPC) and measurement of Total Antioxidant Activity (TAA) of tea are necessary for better understanding the health benefits in tea. The main objective of our research is to evaluate the total polyphenol content and antioxidant activity of several types of tea using a variety of spectrophotometric tests. Furthermore, we have been continuing our study in the investigation of the relationship between total polyphenol content and total antioxidant activity as well as further standardization of total polyphenol tests. Seventeen teas were analyzed and compared in our study. Total polyphenol content of tea was measured by the standard Folin-Ciocalteu's method and a new enzymatic method involving the use of horseradish peroxidase and 4-aminoantipyrine, a chromagenic agent. Total antioxidant activities in teas were assessed by utilizing á, á-diphenyl-â-picrylhydrazyl (DPPH) radical scavenging and Ferric Reducing Antioxidant Power (FRAP) assays. Highest content of polyphenol and strongest antioxidant activity was detected in green teas, followed by oolong teas and then black teas. The comparisons of the above methods revealed the relationship between total polyphenol content and total antioxidant activity of teas. On the basis of the results, the different chemical principles upon which these assays are built can account for the discrepancy in the methods. Moreover, significant differences in the total polyphenol content were found by applying Folin and enzymatic methods. This indicated that the choice of standard material will play an important role in determination of total polyphenol content of food matrix. Thus, further standardization of the new enzymatic method could potentially provide innovative applications in the tea-beverage industry.
Session 18E, Nutraceutical & Functional Foods: General I
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |