Preparation, composition and consumption patterns of tea-based beverages in Arizona

Flavonoids in black and green tea have been implicated in cancer chemopreve ntion. The concentration of flavonoids in tea is likely to vary by preparat ion techniques. Inconsistencies between epidemiological studies may arise f rom the lack of information on methods of preparation. The purpose of this study was to assess the pattern of tea consumption among an older Arizonan population and to determine tea polyphenol and flavonoid levels in the most commonly used tea preparation techniques for a Southwestern US population. A specific tea questionnaire was developed using focus groups and semi-str uctured interviews. The reliability of the tea questionnaire was very high even after 6 months (r= 0.93 for average tea intake/day). Forty samples, re presenting the most typical preparation techniques of hot, iced, and sun te a, were analyzed by HPLC for total flavonoids, catechins, theaflavins, thea rubigins, caffeine and gallic acid. In black tea, the highest concentration s of flavonoids (mug/ml) were found in brewed hot tea (range: 541-692) whil e the lowest concentrations were for instant tea preparations (range: 90-10 0). Results show that tea concentration, brewing time, and beverage tempera ture also have major influences on flavonoid concentrations. Use of specifi c questions focusing on tea preparation and availability of quantitative es timates of tea flavonoids should enhance epidemiological studies of the rel ationship between tea consumption and disease risk. (C) 2000 Elrevier Scien ce Inc.