The latter is a form of processing practised mainly in India in which fermentation occurs on the surface of green coffee beans as they are transported during the monsoon season.
Fungal species (Aspergillus spp. and Rhizopus spp.) were found predominately in monsooned coffees while bacterial species were detected at larger populations
(Ahmad & Magan, 2002).
On the other hand, digestive bioprocessing involves subjecting green coffee beans to a combination of acidic, enzymatic and fermentation treatment as they transverse through the digestive tract of the animal, resulting in the production of two of the world’s most expensive coffees, civet-cat (Marcone, 2004) and black ivory coffee.
Protein hydrolysis observed in green civet-cat treated coffee beans (Marcone, 2004) suggested that the unique traits of roasted civet-cat coffee could partly arise from changes to the amino acids composition of green coffee beans prior to roasting.
However, the specific roles in which the respective microorganisms and the subsequent compositional changes contribute towards coffee aroma modulation still remain to be elucidated given the uncontrolled nature of the aforementioned fermentation processes.