Microbes Help Make the Coffee

When it comes to processing coffee beans, longer fermentation times can result in better taste, contrary to conventional wisdom. Lactic acid bacteria play an important, positive role in this process. Other species of microbes may play a role in this process as well, but more research is needed to better understand their role. The research is published February 1 in Applied and Environmental Microbiology. "We carried out the research at an experimental farm in Ecuador through a multiphasic approach, encompassing microbiological, metabolomics, and sensory analysis," said Dr. De Vuyst. Fermentation was of particular importance. During extended fermentation, leuconostocs -- a genus of lactic acid bacteria used in the fermentation of cabbage to sauerkraut and in sourdough starters -- declined in favor of lactobacilli, said Dr. De Vuyst. Lactic acid bacteria were already present before fermentation, and these acid tolerant lactobacilli proliferated even more during this process. However, it is challenging to draw a causal link between the microbiota and the volatile compounds in the beans -- those compounds that contribute to the coffee's smell -- since many of these compounds can be of microbial, endogenous bean metabolism, or chemical origin," said Dr. De Vuyst.