Evaluation of Tropane Alkaloids in Teas and Herbal Infusions: Effect of Brewing Time and Temperature on Atropine and Scopolamine Content

Abstract

Atropine and scopolamine belong to the tropane alkaloid (TA) family of natural toxins. They can contaminate teas and herbal teas and appear in infusions. Therefore, this study focused on analyzing atropine and scopolamine in 33 samples of tea and herbal tea infusions purchased in Spain and Portugal to determine the presence of these compounds in infusions brewed at 97 °C for 5 min. A rapid microextraction technique (µSPEed®) followed by high-performance liquid chromatography–tandem mass spectrometry (HPLC–MS/MS) was used to analyze the selected TAs. The results showed that 64% of the analyzed samples were contaminated by one or both toxins. White and green teas were generally more contaminated than black and other herbal teas. Of the 21 contaminated samples, 15 had concentrations above the maximum limit for liquid herbal infusions (0.2 ng/mL) set by Commission Regulation (EU) 2021/1408. In addition, the effects of heating conditions (time and temperature) on atropine and scopolamine standards and naturally contaminated samples of white, green, and black teas were evaluated. The results showed that at the concentrations studied (0.2 and 4 ng/mL), there was no degradation in the standard solutions. Brewing with boiling water (decoction) for 5 and 10 min allowed for higher extraction of TAs from dry tea to infusion water.

Recent food alerts and analytical advances related to the contamination of tropane and pyrrolizidine alkaloids in food

“…Regarding miniaturization, alkaline organic extraction followed by solid-phase microextraction (SPME) using molecularly imprinted fibers with cation-exchange interaction was employed for selective recognition of 10 PAs from scented teas (Luo et al, 2022). On the other hand, other works have directly performed the analysis in the prepared infusion samples (Casado et al, 2022b;Han et al, 2022b;González-Gómez et al, 2022c;Martinello et al, 2022;Rizzo et al, 2023a;González-Gómez et al, 2023b;Fernández-Pintor et al, 2023). Analyzing the infusion seems more suitable to avoid overestimation of the real intake and exposure of consumers to these toxins through these beverages, since transfer rate of these alkaloids during brewing is not always complete (Casado et al, 2023).…”

“…Accordingly, some recent works have assessed the transfer rate of these alkaloids in addition to estimating their content in the product. In these cases, after preparing the infusions, the aqueous extracts have been purified before chromatographic analysis by using different techniques, such as SPE, salting-out assisted liquid-liquid extraction (SALLE) and µSPEed (Casado et al, 2022b;Han et al, 2022b;González-Gómez et al, 2022c;Martinello et al, 2022;Rizzo et al, 2023a;González-Gómez et al, 2023b;Fernández-Pintor et al, 2023). It is worth highlighting this last technique, which it is an improved highresolution miniaturized SPE that provides more efficiency and faster procedures at a lower overall cost.…”

“…It is worth highlighting this last technique, which it is an improved highresolution miniaturized SPE that provides more efficiency and faster procedures at a lower overall cost. This miniaturized approach has proved its green potential for both the analysis of PAs and TAs in infusion samples by minimal use of sample, sorbents and solvents (Casado et al, 2022b;González-Gómez et al, 2022c;González-Gómez et al, 2023b;Fernández-Pintor et al, 2023).…”