Objective The dissolved components in the brews of Fujian white teas were investigated.
Method 4 local white tea products of 2 cultivar varieties and 2 quality grades were brewed by the standard procedures for sensory evaluation on white tea. The components in the 3 series of brewed teas were analyzed.
Result (1) After 3 series of brewing the average total dissolved amounts of the components were 9.56 g·hg−1 for polyphenol, 4.78 g·hg−1 for catechin, 4.26 g·hg−1 for soluble sugar, 3.98 g·hg−1 for theabrownine, 3.59 g·hg−1 for thearubigin, 3.26 g·hg−1 for caffeine, 2.38 g·hg−1 for amino acid, 0.45 g·hg−1 for flavone, and 0.12 g·hg−1 for theaflavin, the average total dissolved rates of the components were 78.95% for caffeine, 70.71% for flavone, 66.69% for amino acid, 63.98% for theabrownine, 63.23% for theanine, 61.97% for thearubigin, 55.77% for polyphenol, 53.27% for soluble sugar, 43.31% for EGCG, 40.42% for catechin, and 31.34% for theaflavin. (2) Except for thearubigin and soluble sugar, all the other components decreased in their dissolved amounts and rates from the 1st to the 3rd brewing, among which caffeine,amino acid and flavone showed the highest average dissolved rates of 37.13%,31.54%,29.73% respectively in the 1st brewing. (3) Polyphenol, caffeine, flavone or thearubigin differed significantly (P＜0.05) between its dissolved amounts of 3 series of brewing of the same sample.The dissolved rates of caffeine and amino acid decreased significantly by more than 9% in one more brewing, while the dissolved rates of the components generally did not show regular differences between the varieties and the grades.
Conclusion The dissolved amounts and rates of the components tested, except for thearubigin and soluble sugar, declined from the 1st to the 3rd brewing. In 3 consecutive brewing, due to differences in solubility, caffeine, flavone and amino acid rapidly leached, polyphenol and theanine partly dissolved, and less than 50% of catechin, EGCG and ECG in the dry leaf dissolved in 3 brewings.
DownLoad: