Tea variety and brewing techniques influence flavonoid content of black tea

Abstract

Objective: To examine the influence of variety and brewing technique on the catechins, theaflavins, and thearubigins in black tea using published data. Methods and materials: Differences due to tea variety were examined by comparing values for the characteristic flavanols that are responsible in part for the distinct flavors of the various teas. These included catechins, theaflavins, and thearubigins in varieties of blended teas (from several regions) and unblended teas (from only one region) in the published literature. Total catechins, theaflavins, and thearubigins were calculated per 180 mL serving of tea for teabags of different weights. For brewing techniques, calculations by infusion strength of 1.25% (2.25 g teabag per 180 mL water) and by an illustrative extraction efficiency were compared to analytical results at a 2 min brewing time. Results: The unblended teas (e.g. Assam, Kenya, Ceylon, China, and Darjeeling) varied greatly in the amount and pattern of their flavonoid content. Compared to unblended teas, the blended teas were lower in total catechins and mid-range in theaflavins. Differences in flavonoid content per tea serving were the result of tea variety, weight of tea used, and, to a lesser extent, brewing technique. Significance: Tea variety, weight of tea or teabag, and brewing techniques all affect estimates of flavonoid intake. Databases that include flavonoid data for different varieties of teas and different brewing techniques will be useful for dietary assessment studies. For research purposes it would be helpful to list tea type (black, green, oolong, pu’er), unblended or blended, and if data suffice, for unblended by region (Assam, China, Darjeeling) and for blended by name (Earl Gray, English Breakfast). More research is needed on the effects of brewing techniques so accurate formulas can be developed to determine flavonoid content.