Different Fully-washed and semi-washed coffee processing

Posted on 30/11/2022

Once coffee cherries have been picked, it is necessary to process the crop in particular ways in order to end up with the finished green beans in jute bags - washing being just one of these processes, which varies depending on numerous factors from cost and labour through to resulting flavours. But what is the difference between washed and semi-washed methods of processing?

Well, for a start washed or semi-washed coffee is said to be of a superior quality to that produced by the completely natural method, which costs less overall, as it affords a cleaner and more consistent flavour to the final coffee. Washing coffee beans – sometimes known as the ‘wet method’ of production as opposed to the dry one – sees their outer casing removed using water, before the beans are eventually dried and bagged for shipment. For this reason, the process uses substantial quantities of water.

fully-washed coffee beans

For fully-washed beans, first of all, once picked the cherries are put in water in order to separate them out. The ripe ones will sink, whereas the poor ones will float. Then, the skin of the cherry and some of the pulp is removed from each individual bean by pressing it through a screen using a machine. Nevertheless, a lot of the pulp will still stick rigidly to the beans, so it is then necessary to use either a more traditional ferment-and-wash method or a more modern process called aquapulping, mechanical demucilaging or machine-assisted wet processing to get rid of the last of it.

The former method sees the remaining pulp broken down by fermenting the crop with microbes and then washing the beans with water – something which has to be overseen and monitored very carefully to ensure that the fermentation process does not unfavourably alter the final flavour of the coffee. It is also necessary to thoroughly wash the beans afterwards to ensure that no fermented mucilage remains. Meanwhile, the more modern demucilaging process removes the remaining pulp with mechanical scrubbing, which can be preferable particularly in some hotter countries due to the fact that less water is needed. In addition to this benefit, it is easier to monitor and predict outcomes for the process.

semi-washed coffee beans

Semi-washed, honey process, pulped natural, wet-hulled.

As each has its own merits and intricacies, this article will focus on two main styles of semi-washed methods. 'Wet-hulled' and 'Honey'/'Pulped natural'. The basic steps of all semi-washed processed coffees include; pulping, drying, parchment removal, cleaning and grading.

Honey and Pulped Natural coffee are the same process, just different names. Once ripe coffee cherries have been picked, the outer fruit is removed, but the sticky flesh layer and the mucilage are left intact. The sticky beans are then out out to dry like an 'unwashed' coffee. Once dried, the parchment is removed via hulling and the beans are then cleaned, graded and sorted.

Wet-hulled coffee is specific to Indonesia. It is different from any other method in the world. Once ripe coffee cherries have been picked, the fruit is removed as soon as possible. This is referred to as 'pulping' or 'milling'. The mucilage layer is then washed off the beans. The coffee is then raked across a patio for drying. Once the coffee has reached approximately 30% moisture, it is put through the hulling process to remove the parchment layer. The beans are still malleable at this high moisture content and the beans can often be disfigured by the huller. The reason this is done is because of the high humidity in Indonesia. The farmers and millers are afraid to leave their coffee outside drying for too long, so by removing the parchment skin earlier than usual, the beans are more exposed to the air and therefore dry quicker.

Each seemingly insignificant one of these steps can ruin coffee. If under or over-ripe cherries are picked, the rest is pointless. If the coffee is not pulped immediately after picking, the coffee will taste fermented. If the coffee is left in a big pile to dry it will go mouldy, so the coffee must be dried in a thin layer to ensure even drying. The more we understand about the coffee process, the more we appreciate good quality coffee when we get it.