Influence of genotype, location and processing methods on the quality of coffee (Coffea arabica L.)
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Hailemichael, M.S. 2009. Influence of genotype, location and processing methods on the quality of coffee (Coffea arabica L.). MSc thesis (Horticulture). 105p. Awassa (Ethiopia): Hawassa University.
Permanent link to this item: http://hdl.handle.net/10568/669
Despite the wealth of genetic diversity and wide climate, the yield and quality of Ethiopian coffee is below expectations, largely due to the predominant use of traditional production and processing methods. To this end, this study was undertaken with the focus on identifying suitable coffee genotypes with best quality attributes for the Sidama and Yirgacheffee type types and to study the effect of environment and processing method on their inherent quality. For this, 17 coffee accessions (14 accessions plus 3 landraces) were examined for physical and sensory attributes with factorial complet randomized desiggn. The red ripe cherries were hand picked from three study sites (Awada, Korke, and Konga) and evaluated under three processing methods (wet, semi-washed and sun drying). Besides climatic variables, soil samples of the study sites were analyzed for some physico-chemical properties and associated with the relevant coffee quality parameters. The results depicted significant variations due to locations, coffee genotypes, and processing methods at (P≤0.05) for most coffee quality traits. In addition, the interaction effects between the treatments were significant at (P≤0.05). Accordingly, such coffee genotypes as 9744, 9718, and the local landrace were superior at Awada; while, 9718, 979 and 85294 were the best Sidama types at Korke. Similarly, among the Yirgacheffee types 9744, 9718, and 9728 showed the best results for the physical, cup quality and character. With regard to processing methods, the wet method significantly (P≤0.05) improved coffee quality over the other practices and resulted in better over all quality, citric, and spicy taste for Sidama and citric floral with more acidity for the Yirgacheffee coffees. Dry processed coffee had more viscous and mouth full body, flavor and creamy test. The semi-washed coffee had intermediary result. Coffee quality improvement due to processing techniques followed the descending order of washed, semi-washed and sun dried, indicating the alternative options to be practiced under specific conditions. With regard to treatment interaction effects, coffee genotypes were noted to be site specific in terms of their quality, largely due to adaptation to the prevailing climatic and soil conditions. The combined effect of genotype and processing method was also significant at (P≤0.05), perhaps indicating the existing genetic diversity in bean size and compositions. From the present findings, it can concluded that sustainable production of market oriented best quality coffee types require, among others, careful selection of suitable coffee types, site conditions and post-harvest handling and processing techniques. However, further studies should be progressed mainly in the areas of evaluating and developing suitable landraces for each agro-ecology using other chemical compounds including caffeine. Mapping quality profile of Sidama and Yirgacheffee coffees with the view to target niche markets also remain for future investigations.