What does it mean when coffee beans are labeled "washed/fully washed"?
This term refers to the type of post-harvest processing. After harvesting, the beans in the cherries must be brought into a "dry" state (10-12% moisture content) in which they can be stored, transported, and roasted. Different methods are used in coffee production. The two most commonly used methods are the "natural" or "dry process" and the "washed" or "wet process" (image). There are also others, such as the "honey process," "semi-washed," and various "anerobic processes."
Why are there different methods?
There are several reasons for this. A very important one is the prevailing weather during the harvest, or rather, the microclimate in the region in general. The "natural" process is generally used in regions with a dry climate during and after the harvest. "Washed coffees" are often produced in areas with a humid microclimate. The different methods influence the composition of the ingredients and thus ultimately the cup profile. The basis, however, is and remains the careful handling of the coffee plants and an eye for ripeness during harvest.
In the previous two PRESSE issues ( January 24 and February 24 ), we described the "natural" process and its impact on the cup's final result. This issue highlights the "washed" process.
During the "washed" process, the beans are separated from the cherry pulp. This is done using a "pulper" or a so-called crusher. A pectin-containing layer still clings to the bean, which must be fermented into a water-soluble form. The beans with the pectin layer are placed in large vats of water. They are left there for 24 to 72 hours. Lactic acid bacteria, yeasts, and fungal organisms break down the layer into smaller carbohydrate fractions, which can be dissolved with water. After fermentation, the layer around the beans is washed away with water in a flume (pictured) – hence the name of this process. Due to the different densities of the beans, caused by their ripeness, barriers can separate the heavier and denser (and therefore riper) beans from the lighter ones. This is where the initial selection of qualities takes place. After the washing process, the beans are dried to approximately 11% moisture content on raised beds or flat surfaces. The absence of the pulp and pectin layer facilitates the drying process. This is a significant advantage in coffee-growing regions with very humid climates.
The interaction of the beans with the described microorganisms during fermentation affects the cup characteristics.
At the same time, in addition to the external influence of microorganisms, the germination enzymes in the bean also play a significant role. Contact with water in the vats triggers germination reactions. This causes proteins and carbohydrates in the bean to break down. Therefore, "washed coffees" have a different chemical starter kit for the roasting process than "naturals," which have lower enzymatic germination activity during processing. "Washed coffees" exhibit particularly clear and clean taste and aroma impressions in the cup. We will address this topic in the next issue of PRESS.