The Effect of the Duration and Temperature of Infusion on the Heavy Metal Content of Green Tea

Abstract

Tea is one of the most popular drinks in the world, which contains several important essential micro nutrients that are beneficial to human health. On the other hand, the contamination of tea leaves by heavy metals may pose serious problems to human health. In this research, the concentration of toxic metals (Al, As, Pb, Cr, Cd, and Ni) and essential heavy metals (Fe, Zn, Cu and Mn) in Iranian green tea (IGT) leaves and its infusion were determined using atomic absorption spectrometry. Additionally, the effect of the duration (10, 30 and 90 min) and temperature (80 and 100 ºC) of tea infusion on the content of heavy metals was studied. There was a significant difference between all samples at different time and temperatures. The concentrations range of heavy metals in IGT leaves was 1332-0.023 mg/kg. The highest and lowest metal content was observed for Al and Cd, respectively. The results showed that the heavy metal contents in IGT infusion varied between 11.7 mg/L for Al to 0.0002 mg/L for Cd. The highest and lowest percentage of metal extracted into IGT infusion was observed for Ni and Fe as 73.6 and 2.4, respectively.