Effect of processing methods and drying materials on bean physical and sensorial quality attributes of coffee (Coffea arabica L.) Varieties at gera and jimma

Abstract

Arabica coffee belongs to the family Rubiaceae and to the genus Coffea. It is also the backbone of Ethiopia’s economy, contributing the highest of all exports revenues. The quality of coffee is influenced by several factors of which post-harvest handling is one. Coffee in Ethiopia is processed in two different methods on different drying materials including bare soil uniformly across locations. However, lack of information on the effects of post harvest processing and drying on quality necessitates a comprehensive study. Thus, the objectives of this experiment was to evaluate the influence of processing methods and drying materials on the physical and organoleptic quality attributes of known coffee varieties under Gera and Jimma conditions, and to estimate the economic advantages of coffee processing and drying practices under each agro-ecology. Accordingly, the experiment was conducted at Jimma agricultural research center and Gera agricultural research sub center from October 2009 up to June 2010 using a 2×6×3 factorial experiment arranged in split-split plot, using randomized complete block design (RCBD) with three replications. Days to drying, physical and cup quality parameters were recorded and analyzed using SAS version 9.2 computer package. As a result, variation among the varieties were highly significant (P<0.01) for bean size and hundred bean weight at both sites. Body and bean size showed significant variation (P<0.05) at Gera and highly significant variation (P<0.01) at Jimma for body and shape and make due to the processing methods. The maximum value for odor (10) was obtained from drying material mesh wire, bamboo, palm leaves mat and jute mesh at Gera while at Jimma the maximum value was obtained only from mesh wire. With regard to aromatic quality, drying material bamboo demonstrated significantly the highest value (3.31) at Jimma. Wet processing significantly (P<0.01) increased the value for body from 2.88 to 3.74 at Gera and 3.25 to 3.89 at Jimma. A highly significant (P<0.01) interaction was also noticed between drying material and variety on acidity wherein 74110 dried on mesh wire resulted in the highest (3.39) at Jimma. As to flavor, mesh wire recorded the highest 2.90 at Jimma. Thus from the study the wet processed coffee dried on bamboo, mesh wire, palm leaves mat, and jute mesh had good cup quality. With reference to days to drying, at both locations and using both processing methods, the use of bamboo resulted in earlier drying as compared to the other coffee drying materials. Differently, either wet or dry processed coffee dried on soil was found to be strongly discouraging because of its bad quality. Thus from the study the variety 74110 processed with wet processing method is superior in terms of most of the Quality parameters considered in this study and can be recommended for Jimma Zone specially for Melko. 7440 and 75227 processed with wet processing method had acceptable physical and cup quality at JARC and best at Gera; consequently, can be recommended for Gera. However further researches including biochemical analysis and environmental factors should be conducted to give concrete recommendations