| Abstrak/Abstract |
Indonesia is the fourth largest country in the world as a coffee producer. Coffee has complex chemical structure with volatile and non-volatile compounds, this composition has an important role in the distinctive coffee’s taste. Fermentation is an important stage in coffee processing, it has a direct effect on the coffee’s quality. So far, many people have done traditional fermentation relying on natural microbes in fresh coffee. The purpose of this study was to improve coffee’s quality by controlled fermentation using added yeast, thereby encouraging the sustainability of coffee production. The coffee cherries were taken from a coffee plantation in Merapi mountain area, Yogyakarta. Yeast isolates used were Saccharomyces cerevisiae and Pichia kudriavzevii. The experimental processes of fermentation were carried out on three different environmental variables, namely: fermentation in bioreactor with inoculum, fermentation in bioreactor without inoculum, and traditional fermentation in an open container. Coffee cherries were peeled by pulper machine then kept underwater for 72 hours, except for fermentation in an open container. Data logger was used to monitor the temperature changes, the moisture content, brix, PH, and color change were measured for each 24 hours during fermentation. From the data analyzed, the moisture content and brix were increased during fermentation. The result indicated that fermentation by yeast addition raised acidity in the final coffee result, this can be shown from the PH result that eventually decreased from 5.83 to 5.49 and 6.15 to 4.29, respectively. The maximum temperature for both yeast species addition was reached at a 24 to 48 hours period. The result showed that the color parameter (LAB) was elevated, except the lightness value from Pichia kudriavzevii fermentation. Result in this study revealed that the type of microorganism will determine the characteristics of the coffee produced, such as the acidity. The specific taste and aroma compound were generated during fermentation by different yeast species. |
