Rinsing tea before brewing decreases pesticide residues in tea infusion

Rinsing dried tea leaves before brewing is a traditional way of preparing rolled oolong tea in China. This study analyzes how rinsing green, black, and oolong tea before brewing affects the levels of pesticide residues in the tea infusion. Eight representative insecticides of different polarities were tracked, namely, three neonicotinoids (acetamiprid, imidacloprid, and thiamethoxam), two organophosphates (dimethoate and malathion), and three pyrethroids (bifenthrin, β-cypermethrin, and fenvalerate). The results showed that the eight pesticides transferred into the rinse water at rates between 0.2 and 24% after 5, 10, 20, or 30 s. Rinsing tea before brewing reduced the pesticide risk levels by 5–59% in the tea infusion. Five functional components, such as epigallocatechin gallate and caffeine, were reduced by 0–11% in the tea infusion. The results can be used to develop an effective method of rinsing tea before brewing that reduces pesticide exposure risks.