INFLUENCE OF SUN DRYING METHODS AND LAYER THICKNESS ON QUALITY OF MIDLAND ARABICA COFFEE VARIETIES AT GOMMA-II, SOUTHEWEST ETHIOPIA

^1*Berhanu TSEGAYE, ²Ali MOHAMMED, ³Tesfaye SHIMBER,
⁴Yehenew GETACHEW and ⁵Essubalew GETACHEW.
^1*Ethiopian Ministry of Agriculture, Coffee, Tea and Spices Development Directorate P.O.Box.62347
Addis Abeba, Ethiopia
²Department of Postharvest Management, Jimma University College of Agriculture and Veterinary Medicine,
P.O. Box 307, Jimma, Ethiopia.
³Jimma Agricultural Research Center P.O.Box 192, Jimma, Ethiopia
^4,5Department of Horticulture and Plant Science, Jimma University College of Agriculture and Veterinary Medicine,
P.O. Box 307, Jimma, Ethiopia

ABSTRACT
Coffee is the backbone of Ethiopia’s economy, contributing the highest of all exports revenues. Despite the economic importance, productivity and quality of the crop is very low. In Ethiopia it is processed in two different methods on different drying materials across locations. However, lack of information on post harvest processing and drying on quality necessitates a comprehensive study.Therefore, this experiment was carried out todetermine the effects of altitude, sun drying methods, variety and cherry drying layer thickness on quality of coffee at Gomma-II. Accordingly, on-farm processing experiments were conducted at state owned coffee farms under Limmu Coffee Plantation Development Enterprise (LCPDE) from September up to December, 2010. The experiment was laid out in 3x3x4 Split-Split-plot design arranged in CRD with three replications. The three factors comprise three drying materials: bricks floor, raised beds with bamboo mats and mesh wires assigned to the main-plots. Three coffee varieties: 744, 74110 and 744+74110 assigned to sub-plots and four levels of cherry layer thicknesses: 20; 30; 40kg/m2 (uniformly spread) and the farmers’ conventional practices (40kg/m2) as sub-sub plot treatments. Analysis was computed to estimate the average response suitable for particular Gomma-II. Similarly, cupping was done by three cuppers at (OCFCU) coffee cupping laboratory in March, 2011. The data were computed by using list significant differences (LSD) procedures of SAS version 9.2. As a result, 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; processing coffee on raised beds using appropriate layer thickness loads of 20to 30kg/m2 at mid altitudes produce quality coffee identified as total quality scores ranging 80-89.99 points and can attain “Specialty Grade 1 and 2” classification profiled under Grade 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 specialty coffee.
Key Words: Sun-drying, Layer thickness, On-farm processing, total quality and Specialty coffee