Post-process storage
Finally the green beans are ready for storage. Appropriate conditions of ambient moisture, temperature and
humidity, can stabilize and slow down the deterioration of the raw beans, for example, changes in amino
acid content during storage. As much as possible, the storage time should be as short as possible since
this will be better tolerated in extreme conditions of temperature and humidity. Warehouse should be
relaltively dark with little natural light, well-ventilated but not subjected to cold air. Temperature should be
around 20°C and relative humidity of air at below 60%. Relative humidity of air above 80% can lead to to
faster and more intense discoloration of the beans. Whitening of beans is more influenced by the type of
packing than by storage time. To prevent woody taste and color bleaching of beans (commonly observed
at moisture levels >12%), coffee beans must not contain more than 11±0.5% humidity when processed by
dry process and 12±0.5% humidity by wet process because excess humidity level in beans facilitates
attacks of mould and bacteria. Common mould found in storage of green coffee include Penicillium and
Aspergillus species. Coffee bags can be placed on wooden pallets or be protected by plastic sheets,
however, never stack bags against walls to prevent any type of humidity. Initial storage of 30-40 days of
freshly harvested coffee may improve quality with the disappearance of slightly green taste. Prolonged
storage of hulled coffee will change the color from green to white. Washed coffee are verified to be more
affected than dry processed coffee. Long storage can also lead to chemical degradation of free amino
acids and sugars, and by oxidation of the lipids.
When it comes to transportation of the green beans to roasting facilities, container must be well ventilated
and equipped with ventilation, drainage and moisture-collecting system, free from smells or strange odors.
Relative air humidity, humidity of coffee at time of loading, changes in environmental conditions from the port
of loading to the port of discharge, and the duration of the journey are the critical conditions that can
adversely affect the quality of the beans. The more extreme the climate conditions at loading and
unloading, the shorter the duration of the journey should be. For example, relative humidity should not
exceed 70% during container shipment, otherwise, container must be loaded with smaller load of maximum
285 bags.
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