Comparative study of caffeine content in wild and cultivated coffee beans from Bale Zone, Ethiopia using UV-VIS spectrophotometer

Abstract

This study presents comparative evaluation of caffeine level of cultivated and wild coffee beans as quality indicator. Six samples (three from each wild and cultivated) of green coffee beans from the three main coffee growing districts in Bale zone, Ethiopia were evaluated for their caffeine levels. The well-dried coffee beans were got ready for extraction by grinding to fine powder, boiling by mixing it with water and Na2CO3, followed by vacuum filtration. The caffeine was extracted by liquid-liquid extraction using chloroform and analyzed using UV-Vis spectrophotometer. The results revealed that the mean caffeine levels to be (%w/w) 1.158±0.164, 1.107±0.050 and 1.171±0.150 for Harenna, Dello Menna and Berbere wild coffee samples, respectively. Similarly, the mean value of cultivated coffee samples were 1.217±0.018, 1.208±0.123 and 1.201±0.226% for Harenna, Dello Menna and Berbere sampling sites, respectively. The study showed that the average caffeine level of cultivated coffee beans (1.209±0.122%) is slightly higher than that of the wild coffee (1.146±0.121%). The recovery study result lies in the range of 85.1‒105.0%, indicating the accuracy of the method. The intra-day precision of the method in terms of %RSD lies from 0.34‒1.71%. KEY WORDS: Wild and cultivated coffee, Caffeine, Liquid-liquid extraction, Chloroform, UV-Vis spectrophotometer Bull. Chem. Soc. Ethiop. 2025, 39(9), 1683-1698. DOI: https://dx.doi.org/10.4314/bcse.v39i9.3