DYNAMICS OF MICROORGANISMS THAT PLAY A ROLE IN INCREASING CACAO BEANS (Theobroma Cacao) QUALITIES THROUGH FERMENTATION PROCESS AND ITS APPLICATIONS

• Main Author: Andrian K, Joshua
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/37071
• Institution: Institut Teknologi Bandung

Cocoa beans are an important agricultural commodity for the Indonesian economy. One factor that affects the quality of cocoa beans is fermentation. The fermentation of cocoa beans that has been done so far depends on environmental conditions and microbes that work. This study aims to isolate and select microbes that play a role in improving the quality of cocoa beans through fermentation then compare the inoculation methods and fermentation time and test its qualities using the hedonic and sensory evaluation test. The research stage was carried out by conducting microbial isolation during the fermentation process which is usually done by doing natural fermentation one of which is heap fermentation for 9 days. Isolation of microorganisms is carried out every 24 hours during the fermentation process in three types of media, namely HS (Hestrin Schramm) to isolate yeast and acetic acid bacteria, MRS (De Man Rogosa and Sharpe) to isolate lactic acid bacteria and NA (Nutrient Agar) to isolate other bacteria, especially spore-producing bacteria. The isolates obtained were selected using 2 types of liquid media, namely CPSM-LAB (Cocoa Pulp Simulation Media for Lactic Acid Bacteria) media for yeast, lactic acid bacteria, and other microbes appearing in the first 4 days of cocoa fermentation, then CPSM-AAB (Cocoa Pulp Simulation Media for Acetic Acid Bacteria) for acetic acid bacteria and other microbes that appear in the last 4 days of cocoa fermentation. The selected isolates were tested further using Simpson dominance index for all microbes during fermentation, qualitative tests with minimal medium added by certain compounds to test the activity of pectinolytic, proteolytic, amylolytic, cellulolytic enzymes and alcohol production tests for yeast by measuring using picnometer. For lactic acid and acetic acid bacteria, the test carried out was an acid production test with an acid-base titration method. Growth curves were made from the selected isolates to determine the optimum inoculum age. Controlled fermentation was carried out by solid state fermentation method with 1: 1: 1 inoculum ratio for yeast: lactic acid bacteria: acetic acid bacteria as much as 3.33% (v / w). Variations in the fermentation carried out were in initial inoculation (FA) and gradual inoculation (FB) as well as variations in fermentation time of 3, 5 and 6 days. The fermentation results were then tested for the preference level of several respondents. A total of 68 isolates were obtained on all media based on macroscopic and microscopic characteristics, 15 of which were selected after growing in the CPSM-LAB media and 4 were selected after growing in the CPSM-AAB media. The result showed that of the 15 isolates that grew significantly in the CPSM-LAB selection media, 9 of them are yeast and 6 of them are lactic acid bacteria, while the results of the selection on CPSM-AAB media showed that there were 4 isolates of acetic acid bacteria that grew significantly. Based on further testing of enzymatic activity, metabolite production and microorganism dominance index on the 20 selected isolates, 3 isolates have the most potential in the fermentation process of cacao, namely isolates coded H65X1 for yeast, isolates coded H65X2 for acetic acid bacteria and isolates coded M96X5 for lactic acid bacteria. Optimal age of inoculum for yeast H65X1 isolates, H65X2 acetic acid bacteria and M96X5 lactic acid bacteria were 6 hours, 7.5 hours and 8 hours respectively. Microbial community dynamics for each treatment did not differ significantly between FA and FB treatments. On the first day the yeast dominated the fermentation process followed by the dominance of lactic acid bacteria on the second day and the dominance of acetic acid bacteria on the third. On days 4-6 of fermentation all of these microbes decreased and the process became dominated by other microbes. Based on the results of the sensory evaluation and hedonic tests, when compared with commercial chocolate, the FA fermentation treatment for 5 days at the initial pH of cocoa pulp is 4.34 and at a temperature of 28.3 ± 2.13 oC has the closest quality to commercial chocolate.