Coffee Drying and Processing Method Influence Quality of Arabica Coffee Varieties (Coffee arabica L.) at Gomma I and Limmu Kossa, Southwest Ethiopia

Abstract

Solar tunnel drying and semiwash processing methods are popular among coffee growers in southwestern Ethiopia. However, the effect of these processing methods on coffee quality has not been studied in detail. The objective of this study was to evaluate the effect of processing and drying methods on the quality of coffee varieties at Gomma-I and Limmu Kossa areas in the 2016/2017 growing season. Two processing methods (fully washed and semiwashed) and three drying methods (solar tunnel, artificial, and natural sun) were compared using three coffee varieties (741, 7440, and 74110) to test their effect on coffee quality. Coffee beans processed by semiwash method and dried by solar tunnel produced nondefective (primary and secondary) coffee beans compared with others at both locations. Similarly, coffee beans processed by semiwashed method recorded the highest mean value for shape and make and body than wet processing method. Best coffee bean color, greenish color, was produced from coffee beans processed by the fully washed processing method. All coffee varieties processed by semiwashed method produced medium pointed acidity, the second most acceptable grade value for coffee quality for all drying methods. Coffee beans processed by the fully washed method produced more flavor than semiwash processing method. Coffee beans dried by sun and solar tunnel drying methods also produced better flavor than artificial drier. In general, all coffee varieties processed by semiwash method and dried by natural sun and solar tunnel method produced higher preliminary total quality and total specialty coffee value, graded under specialty grade Q1. Hence, coffee growers in the study area can use semiwash processing method and solar tunnel dryer as an alternative/complementary processing method since they produce better or equivalent quality product with full wash and natural sun drying method.