Abstract:
Coffee quality is affected by pre and post harvest practices. Among these practices, processing method and
roasting are the main ones. Dry, washed and recently introduced semi-washed processing methods are
common green coffee preparations in Ethiopia. Regardless of the processing method used, roasting is required
to obtain typical coffee aroma from green coffee beans. However, comprehensive information on the effect of
processing method, variety, roast duration and their interaction on final quality is not available. Hence, this
study was conducted at Jimma Agricultural Research Centre to evaluate the impact of processing method,
variety and roasting duration on physical quality attributes of roasted Arabica coffee during the 2011/2012
cropping season. It was designed in a factorial combination of three released coffee berry disease resistant
coffee varieties, three processing methods and four roasting durations in completely randomized design with
three replications. The physical quality attributes of roast weight loss, volume change, and bulk density of
roasted coffee were recorded and the analysis was computed using general linear model procedures of SAS
version 9.2. The result indicated that interaction of variety by roasting duration was highly significant (P<0.01)
for roast volume change and bulk density of roasted coffee. The highest roast volume change (116.27%) was
recorded for variety 744 roasted for 10 min and the minimum roast volume change (14.29%) was for variety
74110 roasted for six minutes. Variation on roast physical properties of Arabica coffee during roasting was
profound for coffee quality. The result can be used to enhance cup quality of Arabica coffee aiming at roasting
for different processing methods.
