Rob's Blog | Coffee Processing

The keen-eyed amongst you may have noticed something different creeping into our Rare coffee bean collection: coffee with a new type of processing called Anaerobic."What's this all about?" I hear you ask.

But before we get into the good stuff, clarifying a few terms we use might be helpful. (To keep this blog brief, I will stick to washed and natural processing and not go into their variations).

“Process” or “Processing”
It's a general term and refers to removing the raw green coffee from its fruit (coffee cherry). It includes the fermenting & removal of any remaining mucilage as well as drying & preparing the coffee ready for export.

“Washed Process”
(Removes the coffee bean from its fruit quickly).
Pulped (by machine) to remove skins, the raw bean is soaked in a tank to ferment and soften the remaining mucilage. The coffee is washed multiple times in water to remove the remaining fruit mucilage before drying for export.

“Natural Process”
(Removes the bean from its fruit slowly )
The cherry remains whole and is left in the sun to dry. When fully dry, the (dried) mucilage is mechanically removed. Fermentation occurs as the coffee dries, which cannot be controlled due to the nature of drying it in the sun.

“Fermentation”
The breakdown of a substance by yeasts, bacteria or other microorganisms. (So, for coffee, fermentation helps to break down the fruit pulp/mucilage surrounding the raw coffee bean).

Right, now that's out of the way, let's get into it...

Processing & Flavour (Natural & Washed)

The processing method is one of the factors contributing to how a coffee tastes. The most common method is the washed process, but a natural process is often used when water is a constraint. The fermentation stage of processing can affect the flavour significantly, and unsurprisingly, it also involves the most variables. It's a bit like proving bread! Temperatures (of water in washed process or ambient in natural), duration (how long it's left to ferment) and the microbes involved all add flavour characteristics.

New experimental "Anaerobic" fermentation

When it comes to coffee processing, the term "Anaerobic" implies fermentation in an oxygen-free or low-oxygen environment.

The cherries are fermented in sealed vessels with a one-way valve, which pushes out oxygen and controls the vessels' internal pressure. The temperature and duration of fermentation can be closely monitored and adjusted according to the desired result. This ensures a more controlled process than traditional fermentation methods, creating a different coffee flavour profile.

So, once this controlled fermentation element is complete, processing of the beans can continue using traditional methods (washed or natural). During anaerobic fermentation, other fruits or microbes can be introduced, or different styles of fermentation vessels are used. All this means the sheer number of ways to anaerobically process the coffee is vast.

So why does a producer want to perform this type of experimental processing?

Coffee producers strive to produce the highest quality coffee cherry and achieve the best possible price for their crop. The increased demand for more exciting coffees has led to experimentation in processing. The higher the cup quality generally means the producer will receive more money. Rarity also affects price, as demand for this type of processing has been steadily increasing. However, this new type of processing is experimental and, as such, carries an inherent risk of unwanted defects in flavour. To mitigate this, the producer will typically set aside a small amount of the harvest for this type of processing and follow the more traditional methods for the rest. For this reason, you will often see anaerobic coffees appear in our limited-release "Rare "collection.

What to expect

Complex fruit bombs and wine-like flavours. When processed correctly, these coffees can be exceptional! Keep an eye on our Rare range as these coffees are generally limited release, so they last only a short time! One of my favourites is our El Carmen Camionetta, which is anaerobically processed for 72 hours while being trucked from the farm to the processing station.

This complex process doesn't stop there, but I'll let you read all about it yourself. Go check it out. I can't recommend it enough!