Coffee Processing

What is Coffee?

Coffee is a fruit. What we drink is the seed of this fruit that has been removed from the cherry, then dried, milled, shipped, roasted, ground up, and has some water added (usually hot). Here's a little bit about what goes on before we sip that hot seed juice we all lovingly treasure.


The moment a coffee cherry is picked off a tree, in a lot of ways, its fate is decided. It needs to be nicely ripe to attain a high quality, no two ways about it. Being picked too early or too late can result in a myriad of problems that nobody wants. The precision required of this task is challenged at many points, but one that is made obvious basically anywhere that coffee grows is the landscape.

Steep mountainsides, massive distances, treacherous muddy pathways make carrying a ~60kg sack of cherries no small task. Coupled with the fact that the same trees need to be visited about three times per harvest in order to catch all cherries at their peak ripeness makes this task almost sisyphean. So, next time you're enjoying that brew, remember who to really thank. 

Wet Mill

Okay so now the cherries are picked. They are ready to be processed and dried in one of three main methods. There are a tonne of variances possible here, but we will just be sticking to these three: NATURAL, HONEY, and WASHED. All are intricate in their own way, and all have the potential to result in phenomenal coffees. 


The washed method is the more traditional way to process coffees where I learnt about it, in Costa Rica and Colombia. This is when the cherries are put through a machine called a wet mill, which removes the pulp and mucilage from the seed. After being depulped, the remaining mucilage is washed off, before being set to dry. Removing the rest of the cherry means that this process focuses on the inherent qualities of the seed itself. This often results in bright and clean coffees. 


The honey process begins just like the washed. Cherries are run through the depulper, removing the outer layer. The difference here is that all or some mucilage is left to dry on the seeds, often imparting some of the sweetness during the process. The increase in sugars can also increase body and sometimes lower acidity. There are all types of variations in this process, usually to do with how much mucilage is left on the seed.


The natural process is when the coffee cherries are taken directly to dry, without being depulped. The entire fruit dries out, the seeds still smothered in mucilage. This method can seriously elevate the body and sweetness of a coffee but brings its own risks to the table. Uneven drying can cause problems in the dry mill (getting to that next), or mold can begin to grow in areas of higher humidity levels. The funky sweetness brought on by this process can also bring a boozy flavour, enjoyed by some and not by others. But natural coffees that are done right, allowed to dry slowly and evenly can bring out fruity and exotic characteristics in the cup. 


Now that the seeds/cherries have been set on their processing course, they need to dry out before anything else happens. There are a few ways that this can be achieved. They can be set out onto a concrete patio to dry in the sun, or onto raised beds to grab some shade. Sometimes they’re even placed into a mechanical dryer, often because of a lack of space between the other two.  Whether it’s on a patio or a raised bed, the coffee needs a lot of attention. They need to be consistently moved in order to dry evenly and prevent mold from growing. The length of time varies greatly depending on the climate and exposure to the sun. Sometimes the drying period can be as short as five days and as long as 30 or sometimes even more for natural coffees, until the coffee reaches moisture levels of about 12%. An extended drying period can enrich and enhance cup quality, but does run the risk of the aforementioned problems becoming a reality. 

Dry Mill 

So, the coffee is all dried after sometimes months of hard work has passed. Ready to roast, right? WRONG. There is a papery layer of skin that needs to be hulled off before the coffee is ready for export. This hulling process is done at what's called the dry mill. The parchment is removed and the coffee is sorted by density, size, and sometimes colour. After this sorting, it is often sorted once again by hand before being packed to export. This final step isn’t always a part of a coffee's journey but it's one that stands out as a testament to the care put into its process.



This is by no means an exhaustive resource of all things to do with coffee processing, rather a summary of some of the main practices. The intention is to give reader an idea of the journey that coffee goes through, often before it leaves the area in which it's grown. Even from this quick summary it is easy to get a sense of the amount of hard work that goes into coffee production. From the moment the cherry is picked, excellence is needed to attain what we define as specialty coffee standards. Backbreaking effort and painstaking attention to detail are the bare minimum. Now that we have the bases covered I am excited to delve deeper into the things that make each coffee unique and special, and to acknowledge and pay respect to each and every stage of this often complicated journey that coffee takes to get into your cup.