Coffee Processing

We have quickly mentioned the main coffee processing methods previously when we introduced the Arabica and Robusta coffee types. But didn’t mention precisely why this is a very important step between the production of the coffee and the final product.

How the coffee is processed can indeed have a great impact on the resulting cup, which is why producers ensure that there are as less incidents – also called defects – as possible in order not cause a drop in quality of the final product.

As mentioned in our previous posts, the coffee cherries are taken to a wet mill. That’s where the beans are separated from the flesh and dried afterwards so that they are safe for storage.
For this process, it’s important to know that the moisture content of the bean is around 60%, so needs to be dried to reach about 12% and ensure that they will not rot.

The processing of the beans is made, as mentioned above, in order to ensure the highest possible quality. But more producers are starting to do so in order to obtain a specific taste for their final product and are learning how to “control” it.

As we have already mentioned the 3 main different processes when introducing the Robusta and Arabica, we are now going to take a look at the hybrid processes.

Processing representation

 

Hybrid Processes

The 3 processes presented above are the main ones, but there are other ways that producers may use that we will explain here:

  • The pulped natural process:

    This method consists in removing the outer skin of the cherry by pulping it, allowing the exposure of the fruity layer that will then be dried in the sun with its mucilage still attached. This is considered to be halfway between the dry and wet processing, requiring more processing time and more water to obtain a better quality cup as a final result. The final product tends to present a good acidity in addition to a great body and sweetness, mixing the characteristics of both wet and dry processing.

  • The Honey process: 

    A method that is mainly known in Central America, where the cherries are dried with all the mucilage remaining on the parchment. The cherries are then picked, sorted and depulped before being set on drying patios. The final product tends to present a little more acidity than the pulped natural because of the little fermentation that takes place, but less acidity than the natural and washed processed ones.
    This process is called “honey” due to the mucilage being a bit sticky and slimy. Depending on the amount of light the cherries are exposed to, the process presents different colour spectrum:
    Yellow Honey: the one exposed to the most light, taking about a week to dry thanks to the more important light and heat
    Red Honey: it takes about two or three weeks for the cherries to be dry
    Black Honey: as you may have guessed, this one is the one that gets the less exposure to the light and takes the longest time to dry, demanding more work and attention, making it the most expensive one.

  • The semi-washed process:

    As you may have guessed by the name, this processing method is very close to the washed one, but presenting a few less steps. Commonly known in Indonesia as giling basah this process consists of initially drying the cherries to about 30%-35% of humidity. It is then hulled, stripped of the parchment and finally exposed to dry. Semi-washed coffees present specific traits as the parchment is removed earlier than in the other processes, therefore making the coffee from Indonesia very peculiar. It presents a lower acidity and more body than other coffees while creating several different flavours.

The final stages of the processes

Now that we have presented the different processes, it is important to describe what the final stage is: the hulling of the coffee.

Except for the semi-washed beans, the others are still enclosed in their parchment when leaving the mill. After about 60 days,  the moisture level is low enough to ensure a safe keeping of the beans without risk of them rotting. After this period, the coffee is hulled in a dry mill to remove the parchment before being checked for any default. The more meticulous this process is, the better the final quality (and price) is, making it worth the additional time that is dedicated to it.

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