Levels of Selected Essential and Nonessential Metals in Roasted Coffee Beans of Yirgacheffe and Sidama, Ethiopia

Abstract: The study was conducted to assess the contents of essential and non-essential metals in coffee beans. For this matter, seven essential metals such as K, Mg, Ca, Na, Mn, Cu and Zn and two nonessential metals (Cd and Pb) in four roasted coffee samples (washed Yirgacheffe, unwashed Yirgacheffe, washed Sidama and unwashed Sidama) were determined by FAAS. Closed microwave assisted wet digestion method with addition of concentrated (69-70%) HNO3 and 30 % H2O2 were selected for decomposition of ground roasted coffee samples. Generally, the levels of metals in all roasted coffee samples were found: K> Mg> Ca> Na>Mn> Zn> Cu, but the non-essential metals Pb and Cd were found to be below method detection limit. The digestion method was evaluated by spiking roasted coffee samples and their percentage recoveries were in the range of 95 −104 %. It is suggested that the consumption of roasted coffee beans could be a source of dietary essential metals and a possible entrance path way for trace metals to the food chain