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

Flavonoids in black and green tea have been implicated in cancer chemoprevention. The concentration of flavonoids in tea is likely to vary by preparation techniques. Inconsistencies between epidemiological studies may arise from 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-structured interviews. The reliability of the tea questionnaire was very high even after 6 months (r= 0.93 for average tea intake/day). Forty samples, representing the most typical preparation techniques of hot, iced, and sun tea, were analyzed by HPLC for total flavonoids, catechins, theaflavins, thearubigins, caffeine and gallic acid. In black tea, the highest concentrations of flavonoids (mug/ml) were found in brewed hot tea (range: 541-692) while the lowest concentrations were for instant tea preparations (range: 90-100). Results show that tea concentration, brewing time, and beverage temperature also have major influences on flavonoid concentrations. Use of specific questions focusing on tea preparation and availability of quantitative estimates of tea flavonoids should enhance epidemiological studies of the relationship between tea consumption and disease risk. (C) 2000 Elrevier Science Inc.