DETERMINATION OF CAFFEINE IN RAW AND ROASTED COFFEE BEANS OF ILU ABBA BORA ZONE, SOUTH WEST ETHIOPIA

The study was done to determine caffeine content of coffee Arabica in Ilu Abba bora. 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 substance and depending on the dose, can be a mild central nervous system stimulant, improve cardiac performance, increase brain circulation, and exhibit vasodilator and diuretic effect. It is also increase heartbeat rate, dilate blood vessels and elevate levels of free fatty acids and glucose in plasma. High Performance Liquid Chromatographic (HPLC) method was validated for determination of the levels caffeine in raw and roasted coffee sample of Ilu Abba bora zone. Shim-pack VP-ODS column was used with water: ethanol 65:35 % (v/v) eluent. The detector wavelength was set at 272 nm. Linearity of the method was check from 20-100 ppm and the correlation coefficient was 0.999. The method detection limit was 0.023 ppm and the precision was 1.25% at 40 ppm caffeine concentration. The spiked recoveries for caffeine were 105%, for both Yayo raw coffee and Chora roasted coffee, 102%, for both Chora raw coffee and Mettu raw coffee, 99% and 99.2% for yayo roasted and Mettu roasted coffee bean respectively. The caffeine contents in coffee samples were 57.23 mg/L for Yayo raw coffee, 62.63 mg/L for Yayo roasted coffee, 59.33 mg/L for chora raw coffee, 70.93 mg/L for chora roasted coffee, 64.61 mg/L for Mettu raw coffee and 78.68 mg/L for Mettu roasted coffee. As it can be concluded from the result Mettu rural coffee bean has highest caffeine content followed by Chora coffee and then yayo coffee. Roasting of coffee in all cases also increases the level of caffeine all coffee samples.