Written by JulieReading time 6 min
There are several methods used by producers to process their coffee beans following harvest. These include dry (natural coffee beans), wet (washed coffee beans) and semi-dry processes, as well as the less common (but still prevalent) Honey Process. The flavour profile of a coffee will differ depending on where it was grown and the method employed (including level of fermentation control, drying phase, etc.). There are many criteria that go towards producing a quality cup of coffee. Before looking at these methods in detail, however, let’s take a step back. Where does this drink – so cherished by us all actually come from?
From Tree to Cup
Without going into detail about its origins, coffee beans can be found growing on small trees in the form of flowers and fruits known as coffee cherries (see photo below). A coffee cherry is made up of one or two green coffee beans wrapped in pulp and parchment.
Once picked, the coffee beans are extracted through the methods mentioned above (dry, wet, semi-dry) or by using the Honey Process. As an aside, the method used to harvest the coffee cherries can also vary. These range from:
- picking (a meticulous manual harvest from which only the ripest cherries are selected).
- to stripping (where a tool is used to scrape the tree’s branches and pull off all the cherries in one motion).
- or mechanical harvesting (where the tree is shaken and the falling cherries are caught in a net).
The dry process and natural coffee beans
Once harvested, the coffee cherries are left to dry out in the sun on large flat concrete surfaces or “African beds”. The latter are fabric layers that are woven together and mounted on four legs, thereby allowing the beans to dry from both above and below. The African bed technique is the best way to dry fine coffee beans. Little by little, the pulp dries, shrinks and finally solidifies. Over three weeks, the cherries are turned regularly to ensure that all the beans dry at the same rate.
Once dry, any remaining pulp is removed from the coffee beans. A very fine parchment layer remains, giving these so-called natural coffee beans their slightly uneven straw-yellow appearance. Natural coffee stands out for its earthy profile, resulting in a wilder taste than with washed coffee beans. This method is relatively inexpensive and particularly suited to countries where water is scarce. Coffee producers in Brazil, West Africa and Vietnam use this method. Among the natural coffee beans that our expert team roast at home, the Moka Torban and Moka Sidamo Marabou from Ethiopia are particularly hard to resist.
But why is the coffee sometimes made using a natural process ?
To cut a long story short, there was a time when coffee produced using the dry method was shunned by professionals, who preferred the more sought-after washed coffee beans. To boost their image, some Americans producers in the industry decided to start calling them “natural” coffee beans, banking on the fact that no products were used in the drying process other than the sun. Hence the name “natural coffee”.
The wet process and washed coffee beans
This is still the method of choice for many connoisseurs (but it’s all a matter of taste). For this process, the coffee cherries are pulped within 12 hours of harvest, in order to separate the pulp from the beans. The coffee beans nonetheless retain their mucilage, the fine layer of sweet skin wrapped around them. They are then left to ferment in washing tanks, where they are stirred for between 12 and 36 hours.
After the fermentation stage, the cherries are dried using one of three methods: in a large hot oven, on a concrete surface, or on an African bed.
Once dry, the coffee beans are graded, weighed and usually packed into 60 kg bags. They’re now ready to be shipped! Washed coffee beans stand out for their relatively consistent blue/green appearance. They tend to produce fine, subtle and aromatic coffee, usually with a pleasant hint of acidity. Most high quality coffee is prepared using this process, since the various washing steps eliminate all defects from the beans. The only drawback with this method is the high volume of water required (50 to 100 litres of water for every kilogram of green coffee). Producers therefore need access to a treatment plant nearby to recycle their used water. This method is used in Colombia, Central America, East Africa, South America, the West Indies and Oceania. Among the washed coffee beans that our expert team roast at home, I can strongly recommended Sigri Estate (Papua New Guinea) and Moka Yrgacheffe (Ethiopia).
The semi-dry process and semi-washed coffee beans
Widely used across the Asia-Pacific region, the semi-dry method is most commonly associated with coffee from Indonesia. It consists of removing the pulp from the coffee beans through a mechanical operation (rather than fermentation) while leaving the mucilage intact. Once the fruit has been removed, the coffee beans are carefully washed and then left to dry in the sun. This method consumes considerably less water than the wet method.
The Honey Process
The Honey Process is a sort of mixture of the washed and natural methods. The pulp is removed from the coffee cherries, as it would be in the wet process, but they are then left to dry out in the sun in the style of natural coffee beans. As such, following the pulping stage, the thin layer of outer material (or mucilage) is still present. During the drying process, this is then incorporated into the final coffee. By employing this method, producers can both obtain more sugar than through a washed treatment (where the mucilage disappears during the fermentation stage). It will also generate greater aromatic clarity than with the natural process. There are different kinds of Honey Process (predominantly the black, red and yellow variations) depending on the amount of pulp that is left intact following the initial stage of the process.
This method is only possible for coffee that has been picked manually in order to select only the ripe cherries (and thus avoid the need for sorting). Because this picking is so labour intensive, the Honey Process has still not been widely adopted. So what’s it to be: washed coffee beans or plain coffee beans? The best course of action is to try different coffees produced using all the various methods, then let your palate decide.
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