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Title: Levels of Essential and Non-Essential Metals in Commercially Available Ethiopian Black Teas
Authors: Daniel, Woldegebriel
Advisors: Prof. B. S. Chandravanshi
Keywords: Tea (Camellia Sinensis)
Black tea
Tea infusion
Essential elements
Non-essential elements
Copyright: 2007
Date Added: 11-Dec-2007
Publisher: Addis Ababa University
Abstract: Essential (K, Ca, Mg, Mn, Fe, Zn, Cu and Co) and non-essential (Cd and Pb) metal contents of commercially available three brands of Ethiopian black tea (Wush Wush, Gumero, and Black Lion) and their infusions were analyzed by flame atomic absorption spectrometry (FAAS). In black tea leaves K was found to be the highest amount followed by Ca and then Mg. The heavy metals in black tea leaves were found in lower amount than K, Ca and Mg. Co and the non-essential heavy metals (Cd and Pb) were too low to be detected by the available method (FAAS). Generally, in black tea leaves the order was found as K > Ca > Mg > Mn > Fe > Zn > Cu. The black tea infusions prepared from the black tea leaves were also analyzed for their essential and non-essential metal content. It was found that K was found in highest amount followed by Mg in contrast to the black tea leaves. Co, Cd and Pb were found below their detection limit. In black tea infusion the order in the metal content was found to be as follows: K > Mg > Ca > Mn > Fe > Zn > Cu. Generally, the metal contents of the black tea were found to be higher than those of tea infusion. The extraction efficiency of these metals from black tea leaves to their infusion was also calculated and it was found that highest percent was found for K (47 %) and lowest percent for Ca (12.5 %). Except K the essential metal contents of Ethiopian black tea and their infusions were found to be comparable with that of the black tea and their infusions from the rest of the world. While Ethiopian black tea and their infusions were found to be free from the non-essential (Cd and Pb) metals.
Description: Graduate Project Submitted to the Department of Chemistry In Partial fulfillment of requirements for the Degree of master of Science in Chemistry
URI: http://hdl.handle.net/123456789/345
Appears in:Thesis - Chemistry

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