Coffee Processing (Natural)

Fermented foods are the best foods. Beer, bread, wine, kimchi, sauerkraut, miso, cocoa… The list goes on and on. “Why are we talking about fermented foods?” I hear you ask, “Surely coffee doesn’t fall in this category?”. Well… Coffee is delicious and it definitely has gone through fermentation.

Fermentation is really important when it comes to coffee production and turning a small, cherry-like fruit into just its seeds, without damaging those precious seeds while also making them taste better / different even after they’re roasted. The seeds are covered in protective layers called parchment and silverskin. Fermentation helps break down the silverskin layer and depending on the style of fermentation can also break down the flesh and the fruit skin as well.

The main methods of fermentation and the ones you will most commonly see described on a bag of coffee are: 

  • Dry/ Natural Process
  • Honey/ Pulped Natural
  • Wet/ Washed Process
If you have seen other processing methods, chances are they are variations on these three either with subtle tweaks or with added steps and complexities. 

Let’s start by discussing the oldest and simplest to describe method which is the natural AKA dry process.

It’s important to note that the original reason for processing coffee is not necessarily to ferment the coffee. The main reason for processing coffee is to make it easier to remove the fruit and skins from the seeds, it just so happens that fermentation is what helps break down these layers, imparting flavours along the way.

Often the first step after cherries are picked is to float the cherries in water. Over and under ripe cherries will float along with sticks and leaves, these cherries are separated and processed separately. Sometimes the cherries are sorted visually by hand which can be more labour intensive but use less water.

The next stage in this process is drying the coffee. This is done a couple of different ways depending on location, weather, farm, resources and I’m sure a bunch of other factors. In places like East Africa the most common method is to lay the cherries out on raised beds made from materials that allow airflow around as much of the cherries as possible to help prevent mould and unevenness of drying. In parts of central and South America, special ovens are used for drying as rain is quite common which can ruin the drying process. The time it takes for drying can differ from just over a week to more than a couple of weeks.

It’s during this drying time that the fermentation occurs. As the coffee sits, microorganisms that live in the environment such as yeasts, start to eat away at the sugars and carbohydrates in the cherries and produce different ethanols, acids and gases. Different styles of fermentation impart different flavours to the coffee so natural processed coffees can have distinct cherry, berry and boozy flavours and heavier body than other processing methods.

In recent years, natural coffees have become very popular as single origins as the bold flavours make for distant and interesting brews. Typically Natural coffees are used in blends to add body and sweetness or occasionally in a blend to create an interesting, fruity, milk coffee.

In the next post I’ll talk about washed/ wet coffees, the different ways in which they are processed and flavour differences.

Go buy some natural coffees!