Located on the slopes of Huye Mountain in the Huye District in Southern Rwanda, lies a private washing station owned by David Rubanzangabo. A good chap, David cares deeply about the smallholder farmers who deliver their coffee to his station. Since it was established in 2011, Huye receives cherry deliveries from around 1,330 producers during harvest season, who deliver their freshly picked coffee cherries to 26 collecting stations around the Huye community, where a truck visits daily to collect coffee during harvest season.
A small holding in the district is typically just a quarter of a hectare, or roughly 200 trees, which translates to about 2 bags of coffee. It is entirely bourbon, which, coupled with an altitude ranging from 1,600 to 2,300 metres above sea level, brings about lots of complexity and great flavours to the final brew.
His drive for quality has brought about a big increase in prices for local farmers. Confirmation of the high levels of quality that they are producing is Huye's success in the Cup of Excellence: 2nd place in 2012, and 6th and 11th in 2013 with two competing lots. To encourage consistency of quality, David awards members whose coffees carry the highest cupping scores with the prize of a cow (40 members each won one) or a goat (60 winners last year). A cow makes a huge difference to the lives of a family since it will provide milk for around 6 years and a constant supply of organic fertiliser for the coffee trees.
The processing is based on washing the coffee with a set up that is typical throughout East Africa. The freshly delivered coffee is inspected to ensure only good red and ripe cherries are included. Then it is put into the receiving tank where undesired floaters are removed. The denser, high quality cherries are then pulped before entering a concrete fermentation tank where they are held for 12 to 15 hours. It is a dry fermentation process meaning that extra water is not added. After this the mucilage is loose enough to be washed away and the tank is then filled with water and the coffee turned with a large wooden paddle before being drained. This process is repeated a further 4 times to ensure the coffee is clean before being channelled through water (when further floaters are removed) and is then transported to raised beds for drying. Initial drainage drying is under shade as the coffee could be damaged at this point if it is exposed to too much heat. Then it is taken to the drying tables in the sunshine where the beans are diligently sorted by hand to remove defects, and turned regularly, taking between 15 to 20 days.
The parchment coffee then goes to storage to be held for two months while it conditions (the evening of moisture content) before being trucked to the mill in Kigali belonging to sister company, Rwanda Trading Co. Here the parchment is milled away and any further defects are removed using light sorting machines. Gravity sorting machines are also used to remove broken beans and foreign bodies before the coffee is finally packed into 60 kilogram bags (lined with Grain Pro) ready for export. The coffee is trucked to either Dar es Salaam in Tanzania or Mombasa in Kenya, where it is shipped to our niche roastery on Holy Island!
The decaffeination process
1. The green beans enter a ‘pre-treatment’ vessel where they are cleaned and moistened with water before being brought into contact with pressurised liquid carbon dioxide. When the green coffee beans absorb the water, they expand and the pores are opened resulting in the caffeine molecules becoming mobile.
2. After the water has been added, the beans are then brought into contact with the pressurised liquid carbon dioxide which combines with the water to essentially form sparkling water. The carbon dioxide circulates through the beans and acts like a magnet, drawing out the mobile caffeine molecules.
3. The sparkling water then enters an evaporator which precipitates the caffeine rich carbon dioxide out of the water. The now caffeine free water is pumped back into the vessel for a new cycle.
4. This cycle is repeated until the required residual caffeine level is reached. Once this has happened, the circulation of carbon dioxide is stopped and the green beans are discharged into a drier.
5. The decaffeinated coffee is then gently dried until it reaches its original moisture content, after which it is ready for roasting.
There are several benefits to using this process for decaffeination:
• The agent used for extracting the caffeine is entirely natural and the process can be classified as ‘organic’ due to the complete lack of chemicals used throughout. There is also no health risk by consuming coffee that has been decaffeinated in this way.
• The way the process works means the other compounds in the green bean are left untouched, meaning decaffeination has no effect on the flavour and aroma of the finished product. The carbon dioxide is very selective and doesn’t extract the carbohydrates and proteins in the green bean which contribute to flavour and smell.
• The cell structure of the green bean and the finished roasted bean is unchanged which is of great advantage when working with speciality coffees.
• The by-products are 100% natural and recyclable.