The metal contents of green coffee beans cultivated in major coffee growing zones of Ethiopia (Wollega, Sidamo, Harar, Bench Maji and Kafa) have been determined in representative samples of the five coffee varieties collected from Coffee Quality Inspection and Liquoring Center located in Addis Ababa, the capital city of Ethiopia. Different sample preparation procedures were tested by varying reagent volumes and types, digestion time, digestion temperature and amount of the sample to decompose the green coffee beans and solubilize the metals. The optimal procedure required 4 h to completely digest 0.5 g of green coffee beans with 5 mL HNO3 (70%) and 1.5 mL HClO4 (70%) at 270 oC. Concentrations of metals (Ca, Cd, Cr, Co, Cu, Fe, K, Mg, Mn, Ni, Pb and Zn) were determined by flame atomic absorption spectrometer employing a four point external calibration curve. The accuracy of the optimized procedure was evaluated by analyzing sample digests spiked with standard solutions. Recoveries of the spiked samples varied from 90 to 110% in green coffee beans. The metals levels observed in green coffee beans are comparable to literature reports. Cd was not detected in any of the five samples while Pb was detected at trace level in only one of the five samples. This indicated that the Ethiopian green coffee beans are free from the toxic metals. The Pearson correlation coefficients indicated strong to medium positive or negative correlation among the metals in the green coffee beans. The analysis of variance results at 95% confidence level suggested that there were significant difference in the concentrations of all the metals except K between the five sampling areas. Thus, this study has revealed variation of metal composition of green coffee beans with the geographical origin of the coffee verities. The variation in composition among coffee sample might be due the differences in mineral contents of the corresponding soils.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.