Effect of Sun Drying Methods and Layer Thickness on Quality of Selected Natural Arabica Coffee Varieties at Jimma, South west Ethiopia

Abstract

Coffee is the most important crop to national economy of Ethiopia. Despite the economic importance, productivity and quality is very low. Improper post harvest processing techniques largely contribute to the decline in coffee quality. This calls for intensive efforts to identify post-harvest practices to come up with technical recommendations that improve coffee quality. Therefore, this experiment was carried out to determine effects of altitude, sun drying methods, variety and cherry layer thickness on quality of coffee. The experiment was laid out in 3x3x3x4 Split-Split-Split-plot design arranged in CRD with three replications. The four factors comprise three locations: Gomma-1, Gomma-2 and Kossa farms assigned as a main plot; three drying materials: bricks floor, raised beds with bamboo mats and raised beds with mesh wires assigned as sub-plot. Three coffee varieties: 744, 74110 and 744+74110 assigned to subsub-plot and four levels of cherry layer thicknesses: 20; 30; 40kg/m² and farmers’ conventional practices as sub-sub-sub plot. The data were computed by using SAS version 9.2. The interaction effects were highly significant (P≤0.01) for total coffee quality and significant variations were observed (P≤0.05) for drying period, total raw quality, total cup quality and coffee grades. The finding revealed that; depending on the agro-ecologies, processing coffee on raised beds using appropriate layer thickness loads of 20 to 30kg/m² and 40kg/m² at low/mid and at high altitudes produce quality coffee and scores 80-89.99 points and can attain “Specialty Grade 1 and 2”. While, the conventional systems produce low quality coffee identified as commercial grade classifications profiled under grade 3 to 6. Hence, using appropriate dry processing approaches, it is possible to produce quality coffee at different agro-ecologies.