Influence of processing methods on the quality performance of arabica coffee hybrids and parental lines in jimma zone

Abstract

Despite the presence of wide genetic and ecological variations for improving the desirable traits (yield, quality, disease and pest resistances and drought tolerance) in Ethiopia, the national average coffee yield remains low as compared to other coffee producing countries. Since the inception of a coffee breeding program in Ethiopia, many varieties including the three coffee hybrids have been released for medium altitude areas of southwestern Ethiopia. The quality of the hybrid varieties was acceptable under research stations, nevertheless little is known under on-farm conditions. Moreover, the previous research has given little attention to processing method and environmental effects on bean quality as well as varietal variations in bean quality. The objective of this study was, therefore, to determine the effects of processing methods on the bean physical and organoleptic quality attributes of the released varieties of arabica coffee hybrids, parental lines and local coffees growing under the conditions of Jimma area. For this, selectively harvested ripe cherries from 7 coffee varieties (3 hybrids: Ababuna, Gawe and MelkoCH2, 3 parental lines: 741, 74110 and Dessu, and a local) grown in Seka Chekorsa and Manna Weredas were processed in Wet and Dry methods, and evaluated for bean physical and sensorial quality characters using a factorial arrangement in CRD with 3 replicates. The results depicted that there were no significant variations between locations and the sensorial quality parameters, except body and aromatic quality, did not differ due to the main and interaction effects. However, body had significant variations (P< 0.05) among varieties and between processing methods, with the highest values for Ababuna and wet processing, respectively. Although the result showed statistically significant variation (P<0.01), the mean values for color in both processing methods indicated nearly grayish color. Above screen size14" (ABS), 100 bean weight (HBW), and shape and make (P<0.01) and aromatic quality (p<0.05) were significantly affected by the three-way interaction of location, variety and processing method. Seka * Gawe * Dry, Manna * 74110 * Wet, Manna * Dessu * Wet and Seka * Melko-CH2 * Wet had very good shape and make with uniform appearance. Seka * Gawe * Dry and Manna * 74110 * Wet also showed the highest HBW and ABS, respectively, and more 91% beans of all varieties had bean size greater than screen size14". Manna *Ababuna * Dry and Seka *741 * Dry showed the strong aromatic quality; but the rest combinations had medium. There was positive and significant correlation between most of the cup quality attributes except astringency. But, there was no significant and positive correlation between cup and physical quality attributes, showing the difficulty to use bean physical attributes for cup quality improvement. From this finding, it can be concluded that all varieties exhibited almost similar and fairly acceptable quality performance under research and farmers’ field conditions and two processing methods in the tested Weredas of Jimma zone. However, further studies should be progressed on all physical, cup and biochemical bean quality attributes of more varieties over multi-locations and seasons.