Secondary Coffee Processing
FAQ to green Export coffee:
Over 95 % of the total annual coffee production is exported as green beans. Secondary processing also known as export grading transforms the clean coffee (FAQ) into the various coffee grades that meet the international standards. The process involves cleaning the FAQ, drying the coffee if wet (M.C over 13 %) followed by size grading using perforated screens of the desired size. The sorted beans are the gravimetrically sorted to have uniform specific density before bagging off and loaded into containers for transportation to the ports.
Currently, there are about 19 active export grading factories, four of these are located in the Bugisu region, one is located in Mbarara town in the Western region and the rest are in Kampala.
1. Pre-cleaning and de-stoning:
The FAQ coffee collected from the various suppliers is of mixed quality depending on the individual suppliers storage and handling techniques. The coffee is often wet (M.C > 14 %) and includes extraneous matter e.g. stones, chaff etc. The FAQ passes to the pre-cleaner where the undesirable impurities that are often lighter than the good beans are removed. The wet FAQ passes to a drier. Dry coffee then continues to a destoner where the denser stones are eliminated.
2. Size grading:
The cleaned coffee then passes to a grader, which often consists of a box fitted with screens of various sizes in descending order. The larger beans are retained on the required screen and pass to a lateral exit.
3. Gravimetric sorting:
Although the sorted beans are now of the same size, they may vary in weight mainly due to poor agronomic practices especially the harvesting of immature cherries. The coffee passes over a gravity table where separation occurs at various points on the fluidized bed.
The coffee is then bagged in jute bags of 60 Kg which are then loaded into a container for transportation to the port.
The following are the Ugandan export grades:
Washed Natural Washed Natural
1. Bugisu AA Drugar A Screen 1900 Wur
A B 1800
PB C 1700
2. Wugar A
Drugar = Natural Dry Uganda Arabica
Wugar = Washed Uganda Arabica (other than Bugisus)
Wur = Washed Uganda Robusta.
Other improved grades for the niche markets include Organic and Specialty coffees.