SCREENING OF POTENTIAL MICROBIAL ISOLATES AS STARTER CULTURES AND OPTIMIZATION OF WEST JAVA ROBUSTA COFFEE FULL-WASHED FERMENTATION

• Main Author: Putri, Nurhayati
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/69967
• Institution: Institut Teknologi Bandung

Coffee is an essential commodity that contributes to the Indonesian economy, including West Java. Currently, there are two types of coffee that dominate the world market, namely Arabica and Robusta. Based on data from the International Coffee Organization for the 2020/2021 period, it was recorded that the Robusta market was below Arabica, which was only 36%. However, Robusta coffee still has the potential to be developed, supported by the fact that Indonesia is the largest Robusta coffee-producing country. Accompanied by proper cultivation and processing techniques, the final quality in the form of flavor and aroma can be improved to be able to expand the market of Robusta coffee. One of the processing stages that need to be considered is the fermentation of coffee cherries. Spontaneous fermentation occurs naturally by indigenous microbes in the postharvest coffee process. Improving the final quality of coffee can be done by controlling the fermentation process, including the use of starter cultures or inoculums. Therefore, this study aims to optimize the wet fermentation of West Java Robusta coffee cherries using starter cultures with the best enzymatic performance. The study began with testing activity of the enzyme amylase, pectinase, cellulase, and protease from 13 bacteria and 9 yeasts obtained from previous studies. Based on the results of the most complete enzyme production and the highest enzymatic activity value, two isolates were selected, namely lactic acid bacteria Leuconostoc suionicum with the ability to produce amylase (1.69 ± 0.23 U/mL), cellulase (0.49 ± 0.04 U/mL), and pectinase (0.15 ± 0.1 U/mL); and the yeast Wickerhamomyces anomalus with the ability to produce enzymes amylase (0.22 ± 0.13 U/mL), proteases (0.16 ± 0.01 U/mL), and pectinase (0.21 ± 0.13 U/mL). These two microbes are commonly found in coffee fermentation. Based on the growth curve, the mid-log phase of the two isolates was 8 hours which was then used for starter production. Fermentation of pulped Robusta coffee cherries was carried out with 4 variations consisting of the addition of a starter culture of 1% (v/w) single bacteria (107 CFU/mL), single yeast (107 CFU/mL), a mixture of bacteria and yeast (107 CFU/mL each), as well as the control without addition by any starter culture. The fermentation was carried out for 36 hours at room temperature, then stopped by washing the coffee beans, and dried under the sun for 14 days. Dynamics analysis of the microbial community showed the addition of starter culture could increase the total number of bacteria and LAB at 0 to 6 hours, as well as increase the total number of yeasts throughout the fermentation time when compared to the control. However, based on the cupping test results, the addition of starter culture has not yet produced a significant effect on the flavor and aroma formed in Robusta coffee.