Processing method, variety and roasting duration effect on physical quality attributes of roasted Arabica coffee beans

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.