*2.1. PA Extraction*

Twenty-one types of commercial (herbal) teas were sampled from China and EU countries, including 7 types of teas derived from PA-containing plants and 14 types from non-PA producing plants. Detailed information of the (herbal) teas is listed in Table 1. In total, 147 tea samples, which were present as comminuted leaves, were analyzed. Two grams of (herbal) tea were weighed out and transferred to beaker glasses or brown bottles. Immediately, 150 mL of boiling water was added onto the samples. The infusion was steeped for 10 min, with a gentle stirring for 10 s at 0, 3 and 6 min, respectively. The infusion was allowed to cool down at room temperature, after which it was filtered by passing through a 0.45 μm filter. Fifty milliliters of the infusion were subject to the following cleanup procedure.

**Table 1.** Ingredients and PA-producing property of the studied (herbal) teas.



**Table 1.** *Cont.*

CN, China; ES, Spain; NL, the Netherlands; UK, United Kingdom.
