A Crash Course on Coffee Processing Methods

A Crash Course on Coffee Processing Methods

You’ve probably seen or heard coffees being described as “Washed” or “Natural”. When I first saw these terms in my coffee journey, I was baffled as to what they really meant. I’d assumed that “washed” meant that a coffee would have less dirt on it - you know - since it had been “washed”. And a “natural” coffee was one that was grown without pesticides. After all, it’s “natural”, so it’s got to be organic, right?

A photo of coffee influencer, James Hoffmann, looking disgusted, with the word "NOPE" overlaid

Nope, nope, nope.

If you love coffee, you probably already know that “washed” and “natural” refer to the type of processing method that has been performed on the coffee bean. Coffee processing methods play a critical role in determining the taste, aroma, and overall quality of your coffee. If you’re curious about how these processing methods are performed, read on!

What is Coffee Processing About?

Ultimately, coffee processing is the process of:

  1. Removing the coffee bean from the coffee cherry
  2. Drying the coffee bean until it reaches a desired moisture content

A labelled cross section of a coffee cherry
Image Source:

The above diagram shows the cross section of a coffee cherry. The coffee bean we enjoy drinking is the seed of the coffee cherry. The seed is at the very center of the different layers of the coffee cherry. From the outside to the very center, the coffee cherry’s layers are:

  1. Outer skin: The skin of coffee cherry, much like the peel of any other fruit, like an orange or apple.
  2. Pulp: The flesh of the coffee cherry. It’s sweet and tasty! Unfortunately, there isn’t very much of it to be eaten.
  3. Mucilage: A sticky, sugary, slimy layer that surrounds the coffee seed. I imagine it’s something like the jelly substance in the center of a tomato.
  4. Parchment: A thin, papery layer that surrounds the coffee seed. Imagine the thin papery layer you get on peanuts - something like that.
  5. Coffee Bean: It’s the coffee bean - the stuff that we make coffee out of. It’s the seed of the coffee cherry, and the part you’d want to stick in the ground if you wanted to grow a coffee plant.

Over man’s long history of cultivating coffee plants, farmers across the world have come up with different methods of removing the coffee bean from its cherry and drying it. In the modern age, there are two main categories of processing methods: Washed and Natural.

What is the Washed Process?

In the Washed Process, the coffee beans are removed from the coffee cherry as soon as possible (usually within 8-12 hours of the harvest), leaving behind the coffee bean with its parchment and mucilage still attached.

The coffee beans may then be gathered in piles and subject to a period of fermentation, after which its mucilage is washed off, and the coffee beans (with parchment still attached) are laid out in the sun in thin layers to dry until they reach a desired moisture content.

Once dried, the coffee beans with parchment still attached are stored in warehouses until they are ready to be exported.

Prior to export, the parchment is removed from the coffee beans, leaving behind the raw green coffee, ready to be roasted.

What is the Natural Process (aka Dry Process)?

In the Natural Process, unlike the Washed Process, the coffee beans are not removed from their coffee cherries until they are dried to a desired moisture content.  

So, the coffee cherries are harvested, and then immediately laid out to dry as whole cherries. This takes a lot longer than just drying the bare coffee beans - up to 3 to 4 weeks, whereas drying the bare coffee beans alone would take just 1 to 2 weeks.

The coffee cherries continue to undergo fermentation during the whole drying process, often giving rise to interesting fruity flavours.

Once drying is completed, the coffee cherries are finally depulped, removing the flesh and parchment of the coffee cherry and leaving behind just the bare coffee bean.

Washed vs Natural Process - Differences in Flavour

Broadly speaking, Natural coffees tend to have fruitier flavours and be heavier-bodied, due to the longer contact time they have with the flavour-rich flesh of the coffee cherry.

On the other hand, Washed coffees tend to taste “cleaner” and have brighter acidities.

That having been said, these are just generalisations. We’ve come across plenty of full-bodied washed coffees, as well as natural coffees with bright acidities, so don’t write off a coffee based on its processing method before tasting it!

Special Processing Methods

You may also have heard of other interesting processing methods such as:

We’ve run out of time to cover each one today, but in summary, they’re often about controlling or modifying the type of fermentation that occurs in coffee beans through various methods. In doing so, they produce fascinating new flavours to be enjoyed. They’re really innovative, and we can’t wait to tell you more about them in a future post.

For now, we hope we’ve helped you to appreciate the basics behind the work that goes into making the coffee we enjoy so much. Until next time!