Effect of processing and drying methods on biochemical composition of coffee (Coffea arabica L.) varieties in Jimma Zone, Southwestern Ethiopia

Abstract

There has been minimal research on the effect of location, processing, and drying methods on the biochemical composition of Ethiopian coffee varieties, despite extensive research on the biochemical compositions of green bean and roasted coffee and their effects on cup quality. The current studyaims to close this gap in the literature. Its goal is to determine the impact of coffee processing (fully washed and semi-washed) and drying procedures (natural sun, artificial and solar tunnel) on the biochemical compositions of coffee varieties (741, 74110, and 7440) at Gomma-I and Limmu Kossa, southwest Ethiopia. The biochemical compositions were quantified using a Fourier Transform-NIR spectrometer prediction model. The results showed in both locations, the interaction impact of varieties, processing, and drying methods considerably influenced most of the biochemical contents of the green bean. At both locations, all varieties processed by full wash and dried by artificial produced higher caffeine content. At Gomma I, variety 741 processed by semi-wash and dried by artificial method produced higher TCGA value than the other treatment while the finding at Limmu Kossa was a bit complex. At Gomma I, Arabica coffee varieties (7440 and 74110) dried by artificial produced more sucrose content regardless of the processing methods used. In general, greater mean values of caffeine, TCGA, trigonelline, and sucrose content of green beans were recorded from artificial. Hence, the effect of varieties, growing conditions, processing and drying methods on the biochemical compositions of coffee is highly complex and location specific recommendation is required to get better quality.