You will notice that on the labels on each bag of coffee from Roastworks, we detail the processing method that was used.
Once the coffee cherries have been picked, the process of removing the outer skin and flesh from the cherry to access the coffee bean begins. There are various ways of carrying out this process, and the method used by the farmer and processing mills at origin can greatly impact the final flavour in the cup.
TYPICAL CUP PROFILES
- Dry / Natural Process
- – Countries with little water and hot climate (Africa)
- – Look for berries, wine tannins, currents
- Wet / Washed Process
- – Countries with good pure mountain water (Central America)
- – Look for citrus acidity (lime, lemon, orange peal, green apple)
- Pulped Natural / Honey Process
- – Countries with water supplies and hot climate (Brazil)
- – Look for sweetness, caramel, molasses, sugar cane
|COFFEE CHERRY LAYERS|
|1 centre split|
5 pectin layer
6 pulp mucilage
7 outer skin
DRY / NATURAL PROCESS
The Dry Process, also known as the Natural Process, is the oldest method used. These coffees are dried by leaving all of the coffee cherry intact around the coffee bean. This allows the naturally occuring ‘sweet and fruity’ flavours within the cherry flesh to be absorbed by the coffee bean.
After the cherries have been picked, they are left out to dry in the sun on large concrete or clay patios. The cherries are raked and turned several times a day to ensure even drying, as the outer skin and inner flesh (the pulp mucilage) shrivels up in the heat.
The process takes around four weeks before optimum moisture content is reached, at which time a milling machine is used to remove the dried cherry flesh and expose the bean.
This processing method is used in countries where water is scarce and there are long dry hot spells such as Ethiopia.
The dry process gives the coffee a heavy body, and smooth sweet complex cup, typically with winey or berry notes.
WET / WASHED PROCESS
The WET PROCESS, also known at the WASHED PROCESSis a more involved method where the outer skin and pulp mucilage is removed before the inner bean is dried.
After picking, the coffee cherries are sorted on vibrating screens, before being placed into large flotation tanks. The aim of the flotation tanks is to sort ripe and unripe cherries (ripe sink, unripe float) and the unripe ones are discarded at this stage of the process.
The ripe cherries are then processed through a ‘pulping’ machine which strips the outer skin and almost all of the mucilage from the beans. The beans are then left in tanks filled with fresh water for around twenty four hours to allow the natural enzymes and bacteria begin to break down the remaining mucilage further.
The beans are then typically sun dried on concrete patios, and raked regularly to aid even drying. After around two weeks, the beans are ready for the final stage of the process which is ‘polishing’ to remove any remaining silver skin, and then they will be graded according to size of the final bean.
This process is used in countries where the brightness and acidity of the coffee is a feature such as Colombia and Central America. This process results in a cleaner, brighter citrus fruit flavoured coffee.
PULPED NATURAL / HONEY PROCESS
Pulped Natural, also known at the Honey Process, begins in the same way as the washed process, except that after sorting, the beans are left with the mucilage still on them. Different amounts of mucilage can be left – from white (least) to black (most).
The result combines the best cup results from both the natural and wet processing methods, giving the good body of the natural process combined together with the acidity of the wet process.
The pulped natural process is typically used in countries with low humidity where drying can be done rapidly such as Brazil, who have perfected this processing method.
Each processing method has pro’s and con’s, and typically the option chosen by the farmer is dictated by the climate in which the coffee is grown. For example, it would be extremely difficult for farmers in high humidity countries to process their crops using the pulped natural / honey process without risk of an undesirable level of fermentation occurring. Equally in countries where the temperature was cooler or prone to frequent rainfall, utilising the dry process significantly increases the risk of mould forming.
By combining coffees from different growing regions and processing methods into a blend, roasters are able to balance cup profiles together to give a sense of body as well as balance the acidity and sweetness.