Abstract—Cocoa beans fermentation is an important step in the post-harvest processing of cocoa beans. This complex mix culture fermentation produces metabolic products that serve as the precursors for the flavor development process. Modification in the dynamics of microbial population during the fermentation may alter the overall microbial activity and thus may impact the fermentation process. Addition of microbial starter was thus suggested to improve the cocoa bean fermentation process. This paper discusses the effects of Lactic Acid Bacteria (LAB) starter addition to the cocoa bean fermentation. Dynamics in microbial population, i.e. yeast, lactic acid bacteria, and acetic acid bacteria were analyzed as well as the sugar components, metabolic products, and the fermentation index during the fermentation. The addition of LAB starter was observed to accelerate the growth of both lactic acid bacteria and acetic acid bacteria, leading to the increase in the ethanol, lactic acid, and acetic acid concentration. Overall it increases the fermentation index and potentially shorter the fermentation time.