The microbial ecology of cocoa bean fermentations in Indonesia

Cocoa beans are the principal raw material of chocolate manufacture. The beans are subject to a microbial fermentation as the first stage in chocolate production. The microbial ecology of bean fermentation (Forastero and Trinitario cultivars) was investigated at three commercial fermentaries in East Java, Indonesia by determining the populations of individual species at 12-h intervals throughout the process. The first 2-3 days of fermentation were characterised by the successional growth of various species of filamentous fungi, yeasts, lactic acid bacteria and acetic acid bacteria. The principal species found were Penicillium citrinum, an unidentified basidiomycete, Kloeckera apis, Saccharomyces cerevisiae, Candida tropicalis, Lactobacillus cellobiosus, Lactobacillus plantarum and Acetobacter pasteurianus. The later stages of fermentation were dominated by the presence of Bacillus species, mostly, Bacillus pumilus and Bacillus licheniformis. Glucose, fructose, sucrose and citric acid of the bean pulp were utilised during fermentation, with the production of ethanol, acetic acid and lactic acid that diffused into the beans. The filamentous fungi were notable for their production of polygalacturonase activity and probably contributed to the degradation of bean pulp.