B-TIP – PROCESS PT.1 – THE BASICS
Let’s have a conversation about process.
Process hugely influences the flavour of our coffee – but how exactly? The coffee ‘beans’ that we drink are in fact the seeds of a piece of fruit, referred to as a ‘coffee cherry’. How this seed is removed (or processed!) dramatically changes the cup qualities of the end product.
The two main processes are wet (or washed) and dry (or natural). We can very basically liken the difference in cup notes between the processes to fresh and dried fruit. Think of a grape – a fresh, green grape has bright acidity alongside a lovely fruity sweetness, leaving your mouth watering with a crisp finish. A dried grape (raisin) still has acidity but it tends to be more jammy, with a deeper more molasses-y sweetness and a textured finish.
We’re running a pair of almost identical Ethiopian coffees in the coming months where the only difference is the way the coffee has been processed – keep process in mind as you’re tasting these coffees.
So how do these processes work, I hear you ask?
WET (WASHED) PROCESS
The specifics of this process differ a little from country to country, but here’s a basic run through:
- Picking and sorting: Ripe fruit makes perfect tasting coffee. A floatation tank is used to separate under ripe and damaged coffees; the good stuff sinks while the poorer quality coffee floats, and is channeled away from the top quality.
- Getting the seeds out: The high quality coffee cherry that passed the sorting process goes into a pulping machine, which squishes the fruit to separate the outer skin from the seeds.
- Fermentation: The skins are discarded, while the seeds are still covered in a thick layer of fruit pulp which is removed by allowing fermentation to occur. The amount of time this takes depends on temperature; colder temps mean slower fermentation, and this will change throughout the season. Fermentation is complete once the seeds are free from all fruit pulp and feel gritty when rubbed together. Frequently, the seeds then undergo a vigorous rinsing or an additional 12-14 hour water soak to remove any last traces of pulp that may be present.
- Drying: The coffee at this stage needs to be evenly and carefully dried down to a moisture content of around 11%. The coffee seeds are still encased in a protective parchment layer, which are placed to dry on raised beds, concrete patios or mechanical driers.
DRY (NATURAL) PROCESS
Dry process coffees differ to the wet process above:
- Picking & sorting: As above, the ripeness of the coffee fruit is paramount to the flavour of the end product. A water flotation tank is also used in this process, to separate the dense high quality coffee cherries from the underripe and damaged cherries.
- Fermentation & drying: The whole cherry is placed on raised beds, concrete patios or even mechanically dried with the coffee seed still encased in the fruit skin and pulp. This is where sugars from the fruit ferment for the drying period. As above, these coffees are dried to around 11% moisture content.
- Getting the seeds out: After drying, the coffee is hulled using a machine that removes the outer layer of dried fruit, skin and parchment leaving just the seeds. This is true for all coffees, including both washed and natural!