Study on lead levels in infusion time of imported green and black tea (Camellia sinensis L)

Nowadays, tea is the most popular and frequently consumed beverages in the world after water. There are some beneficial trace elements in tea such as fluoride, caffeine and essential minerals, although there may be heavy metals in tea leaves which threat seriously human health. Therefore, the main objective of current study was to determine and monitor lead content in imported black and green tea leaves (Camellia sinensis L) and time of infusion and to compare the release of Pb from them by the time factor.

The mean content of lead in 450 brewed samples of green and black tea were determined in three different duration time of infusion (5, 10, and 15 minutes) by graphic atomic absorption spectrophotometer. Samples were prepared by wet digestion method due to international protocols AOAC by concentrated nitric and hydrochloric acid. Analysis of variance (ANOVA) was employed to detect significances among samples from different time of infusion in samples.

The results showed that in the brew of dry black and green tea samples, the amount of lead was less than the allowable limit of the dry tea sample (1ppm). Also the amount in the brewed tea in 15 minutes was higher than 10 minutes and it was higher than 5 minutes.

The amount of lead in the brewed tea was lower than in the dry samples. The best time to brew tea is 5 minutes, when the amount of lead is the lowest and the organoleptic properties have the best conditions in terms of flavor.