Determination of Caffeine Content and Phytochemical Screening Of Raw and Roasted Coffee Beans of Bench Sheko Zone, Southwest Ethiopia

Abstract

Caffeine is a naturally occurring alkaloid which is found in the leaves, seeds or fruits of over 63 plants species worldwide. The most common sources of caffeine are coffee, cocoa beans, cola nuts and tea leaves. Caffeine is a pharmacologically active ingredient and depending on the dose, can be a central nervous system stimulant, improve cardiac performance, increase brain circulation, and exhibit vasodilator and diuretic effect.Therefore, the objective of this study is to determine caffeine content and phytochemical profiles of coffee beans of Benchsheko zone in south west region. The coffee beans were collected from four different areas of Benchsheko zone (Debrework, Sheko, Shebench and Mizan). The coffee beans were roasted and ground using manual grinder. Extraction of raw and roasted coffee beans was performed using H2O:CHCl3 for GC-MS analysis and it was carried out sequentially using petroleum ether, chloroform, acetone and methanol for phytochemical screening tests and bioassay. Gas Chromatography - Mass Spectrometry (GC-MS) method was validated for determination of the levels caffeine in raw and roasted coffee sample of Bench Sheko zone. Agilent 5977B GC/MSD column was used with water: chloroform 50:50 % (v/v) eluent. Linearity of the method was check from 1-10 μg/L and the correlation coefficient was 0.9946. The spiked recoveries for caffeine were in the range of 100.64% to 117.6% for the raw and 83.77% to 115.83% for the roasted coffee. The caffeine contents in coffee samples were 7.45 μg/L and 5.8 μg/L Mizan roasted and raw coffee;9.82 μg/L and 5.62 μg/L Debrework roasted and raw coffee; 8.01 μg/L and 4.94 μg/L for Shebench roasted and raw coffee;8.22 μg/L and 5.42 μg/L for Sheko roasted and raw coffee, respectively. Phytochemical screening revealed presence of alkaloids, phenolics, flavonoids and terpenoids in coffee beans.As it can be concluded from the results, 21.9 - 42.8% of the caffeine content of coffee beans increases upon roasting.