Characterization of bitter taste theacrine in Pu-erh tea

Abstract

Theacrine is a kind of purine alkaloid with a similar chemical structure to caffeine. Caffeine influences the bitterness of tea soup greatly, but the role of theacrine in the taste of Pt (Pu-erh tea) soup remained unclear. In comparison with tableland tea (TT), ancient plant tea (APT) has a more abundant and persistent bitter taste. This paper focused on whether a relationship could be formed between theacrine and the taste difference of APT and TT, and how theacrine affected the characteristic taste of Pt soup. To aims, the study detected the content of theacrine and caffeine in APT and TT, the leaching behavior, and the recognition threshold of theacrine at 25 °C and 45 °C. The leaching of theacrine was slow, about 0.67-fold of caffeine when brewing for 30 min. The overall levels of theacrine of APT were higher than TT. Besides, the recognition threshold of theacrine is 18.45 mg/L and 23.24 mg/L at 25 °C and 45 °C, respectively. In conclusion, the low recognition threshold and a different level of theacrine between APT and TT might lead to APT’s intense bitterness. The leaching of theacrine was a slow process that contributed to the APT’s endurance of repeated brewings.