Abstract:
This research project was done to investigate the influence of different methods of coffee processing on quality of the final product. The processing methods studied were wet pulping, hand pulping and eco-pulping. These processing methods vary on their modes of pulping and mucilage removal. The work was carried out using two cultivars of Kenya arabica coffee (CojJea arabica) grown in Nyeri County near Mt. Kenya. The quality parameters determined in the study included; physic-chemical properties, aroma profiles and sensory qualities of the processed coffee. The results showed that the processing methods did not have significant variations in most physico-chemical parameters apart from the mass, density and pH of the green beans. The variations on the mass and density could indicate some losses of chemical components of coffee due to the effects of processing methods used. The variation on the pH could indicate the changes which occurs in the coffee beans during fermentation process with those with lower pH indicating more acidic components than those with higher pH. The processing methods showed significant variations in the intensity of aroma compounds with the wet pulper method showing higher intensities for the alcohols and furan compounds while the hand pulper method showed higher intensities for the ketones and acid compounds. The eco pulper method showed higher intensities for the aldehydes, pyrazines and phenol compounds. There were variations in the levels of the sensory attributes with the eco pulper methods showing higher levels for aroma, body, balance and overall acceptability. The hand pulper also showed higher intensity for the acidity and overall acceptability. The results of the sensory attributes were computed to give the final score of the quality and the eco-pulper and hand pulper methods showed higher final quality than the wet pulper method. This reveals that the wet pulper method which is using fermentation and excess water in processing could be losing more chemical components than the hand pulper and eco-pulper method hence lowering its quality. It was therefore recommended that the new ecological coffee processing technology which uses mechanical method for mucilage removal could be adopted for coffee processing since it has no negative effect on the overall quality of the coffee, more environmental friendly and could reduce cost of production for coffee.
