How does it work? Robusta coffee is usually only sun-dried, meaning that the peel around the beans dries off. The beans are then roasted. On the other hand, Arabica beans always undergo a fermentation process before roasting and drying to remove the skin and gum layer around the bean.
This is called cold processing. The researchers have optimised this fermentation process, which is generally rather improvised. They made it controllable, with clean concrete tanks, clean water, specific lactic acid bacteria selected in the laboratory, and different fermentation times. The longer the process, the more complex and flavoursome the coffee tastes.
Further research still needs to be carried out to determine whether fermentation affects the taste of the coffee beans. The initial results were recently published in the scientific journal, Applied and Environmental Microbiology.