The process starts when lorries off load sacks of parchment coffee from the factories located around the coffee growing areas. Parchment is coffee whose red skin has been removed. This is done at the coffee factory level. The parchment is weighed at the weigh bridge before it is taken to the parchment store. It is at this point where the expected milling loss is determined through a sample taken from each consignment to check for moisture content, diseased beans and other impurities. A farmer therefore knows in advance what they expect to get out of the milling process.
2. The milling process begins with the parchment being put into the feeding hopper where the pre-cleane removes impurities such as stones, metallic objects and papers. Only the coffee and husks go to the huller.
3. Hulling machinery removes the parchment layer from the coffee. During the hulling, a fan sucks the husks to the husk chamber and the beans go to oscillating screen to separate and return the unhusked coffee back to the huller. Bad beans are also removed.
5. The coffee is then graded according to size. Beans are sized by being passed through a series of screens. The larger the bean, the better the quality. This gives the six grades; AA, AB, PB, C, T and E. They are then sorted according to weight by using a gravity separator to separate heavy from light beans. The lighter coffee is removed because it affects the taste, ensuring that only the finest quality coffee beans are exported. The lighter coffee of grades AA, AB, PB and C are put together into a new grade called TT.
6. Finally, beans are put into standard bags of 60 kilograms and labeled ready for the market.