Residue pattern of polycyclic aromatic hydrocarbons during green tea manufacturing and their transfer rates during tea brewing

ABSTRACT

Residues of polycyclic aromatic hydrocarbons (PAHs) in green tea and tea infusion were determined using gas chromatography-tandem mass spectrometry to study their dissipation pattern during green tea processing and infusion. Concentration and evaporation of PAHs during tea processing were the key factors affecting PAH residue content in product intermediates and in green tea. PAH residues in tea leaves increased by 2.4–3.1 times during the manufacture of green tea using the electric heating model. After correction to dry weight, PAH residue concentrations decreased by 33.5–48.4% during green tea processing because of PAH evaporation. Moreover, spreading and drying reduced PAH concentrations. The transfer rates of PAH residues from green tea to infusion varied from 4.6% to 7.2%, and PAH leaching was higher in the first infusion than in the second infusion. These results are useful for assessing exposure to PAHs from green tea and in formulating controls for the maximum residue level of PAHs in green tea.

KEYWORDS:

• Polycyclic aromatic hydrocarbons
• green tea manufacture
• tea brewing
• dissipation pattern
• transfer rate

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the earmarked fund for Innovative Research Team in the Chinese Academy of Agricultural Sciences [grant number CAAS-ASTIP-2014-TRICAAS], the Modern Agro-Industry Technology Research System [grant number CARS-23], and National Natural Funding [grant number 31671941].