MICROBIAL INTERACTIONS BETWEEN CANDIDA TROPICALIS (H1Y4-1) AND LACTIPLANTIBACILLUS PLANTARUM (H5B7-1) DURING CACAO BEAN FERMENTATION WITH CACAO PULP SIMULATION MEDIUM

• Main Author: Cintantya, Amadea
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/78364
• Institution: Institut Teknologi Bandung

Cacao is considered one of the most important plantation commodities in Indonesia, especially for the community of people in Kampung Coklat Senara, West Nusa Tenggara. However, the quality of naturally fermented cocoa beans obtained from Kampung Coklat Senara is still inconsistent and can be improved via a controlled fermentation process. Previous research considered 2 superior microbes obtained from the natural fermentation of cocoa beans, namely Candida tropicalis (H1Y4-1) and Lactiplantibacillus plantarum (H5B7-1), through observation of microbial activity. This study aims to (1) determine the growth kinetics of C. tropicalis (H1Y4- 1) under aerobic and facultative anaerobic growth conditions in Cocoa Pulp Simulation Medium (CPSM); and (2) study interactions between yeast and lactic acid bacteria (LAB), as well as changes in metabolites during CPSM fermentation by yeast and LAB, with yeast:LAB ratio=1:1 and 10:1. The growth kinetics of C. tropicalis (H1Y4-1) were determined by calculating microbial growth, pH, dissolved oxygen concentration, as well as concentrations of substrate and primary metabolites (glucose, acetic acid, citric acid, and ethanol) in CPSM. Interactions between yeast and LAB in cocoa fermentation were determined by quantifying microbial population dynamics, concentrations of substrates and primary metabolites, as well as concentration of amino acids in CPSM. Results showed that the growth rate (?) of yeast in aerobic and facultative anaerobic conditions were 0.36/hour and 0.29/hour, respectively; and oxygen consumption rates by yeast were 0.35 ppm/hour and 0.26 ppm/hour. The rate of glucose consumption (1.2 gr/hour) and ethanol production (0.16 gr/hour) were higher in yeast cultivated on aerobic conditions, while changes in the concentrations of acetic acid and citric acid were relatively similar for both cultivation conditions. Growth of the yeast and LAB consortium in CPSM shows that LAB growth tends to dominate over yeast. The tendency of LAB overgrowth is shown in the variation of yeast:BAL=10:1, but not in yeast:BAL=1:1. Growth of the consortium produces primary metabolites in the form of lactic acid, ethanol, and acetic acid. The amino acids that were most abundant in the medium during the fermentation process of both growth variations were glycine, glutamic acid, and proline (average concentrations 451 mg/L; 334 mg/L; 256 mg/L). Based on the results of this research, it was concluded that the growth kinetics of C. tropicalis (H1Y4-1) was more optimal when cultivated aerobically. Interactions of yeast and LAB in natural fermentation are optimum at a microbial ratio of yeast:LAB=1:1, thus supporting the thesis that the addition of an LAB starter culture to the fermentation of cocoa beans (where yeast:LAB=1:1) can produce cocoa beans with better quality compared to natural cocoa fermentation (where yeast:LAB=10:1).