Determination of four aflatoxins on dark tea infusions and aflatoxin transfers evaluation during tea brewing

In daily tea drinking, little is known on aflatoxin transfers from tea-leaf to infusion during brewing and the actual intake. A verified aflatoxins analytical method on tea infusion is significant to the exposure assessment. Here, an optimal method 3 (M3) was screened and validated on four aflatoxins (B1, B2, G1 and G2) simultaneous deter-mination. Recoveries of AFG1 and AFB1 were 87.37 %+/- 1.99 %-102.03 %+/- 8.62 %, and AFG2 and AFB2 were 83.99 %+/- 8.65 %-100.14 %+/- 1.69 %. The correlation coefficient on the fortified samples determination was > 0.99 for each aflatoxin. In accuracy and precision validation, aflatoxins recoveries in high and low fortified samples were 85.94 %-103.83 %, and RSDs were 2.20 %-9.15 %. Method applicability test showed that the M3 was qualified for six different dark tea types. Extraction rate of 30-days stored AFB1 fortified tea-leaf by ace-tonitrile-water (84:16, v/v) was < 50 %; meanwhile, only 2.94 % spiked AFB1 was released by ten times tea brewing which indicated that Puerh tea have strong adsorbability to aflatoxin.

Automated summary

This study screened and validated an optimal method for the determination of aflatoxins in tea infusion, including four types of aflatoxins. The results showed that the method has high applicability and accuracy, and Puerh tea has good adsorption ability to aflatoxins.