Coffee Knowledge Base

15 February 2024

The washed coffee bean processing method

The washed coffee bean processing method

When harvesting or picking coffee berries, the beans must be removed from the berry. There are four different methods to do this, and each method may vary from country to country and between regions. There is the dry method, the wet processing or washed method, the semi-dry method, which may also be called the semi-washed, pulped natural, or the honey method depending on the country, and there is the fairly new anaerobic method. Here we will explain the washed processing method. 

Washed Processing Method

To safeguard coffee quality, processing must be done within eighteen hours after harvest. Processing usually takes place in the evening and night following the daytime picking. The processing method is crucial for the flavor in the cup, but no particular method is better or worse than another. Each method, dry or wet, produces a completely different flavor spectrum, and growers often use different methods to create distinct flavor profiles. After processing – and regardless of the method – the beans are always dried because a coffee bean must have less than 12% moisture content before it is suitable for transportation.

With the washed method, the berries are washed until all the fruit flesh is removed, and it is done as early as possible, no later than twelve hours after picking. Firstly, the beans are dry-fermented. This should not take too long, so that over-fermentation is averted. Otherwise unwanted flavours will occur, e.g. a rotten-fruit, wine-like or even a vinegar flavour. The beans then flow through a water chute (with several lanes). The water level in the water chute is raised so that the beans are fully immersed in the water for about 24 hours. The lighter beans will float, and the heavier ones sink. This is helpful as a method for selection. The lighter beans are not mature and are therefore of lower quality. The heavier ones that sink are fuller, more mature berries and therefore of better quality.

The next stage occurs at the end of the line, where a wooden board blocks the end of the chute. All the beans that float over the pallet, the floaters, go to a separate washing basin. The ones that remain on the bottom of the chute, known as the sinkers, the better-quality beans, are discharged into another washing basin.

The washed method is often used after mechanical picking, because it is easier to separate the better beans from the poorer quality ones. The beans are then dried once more in the sun on beds, on patios or in a drying machine, because the water content must be reduced to less than 12%. Fully washed coffee has a clean and pure taste. The ‘body’ of the coffee is somewhat reduced here, but you get a fresh and more lively coffee with more acidity instead.

As mentioned in the beginning there are 4 different types of processing coffee beans. If you would like to know more about the other 3 methods, we recommend you to read the following blogs:
The dry coffee bean processing method
The pulped natural coffee bean processing method
The anaerobic coffee bean processing method