Coffee Processing Methods

Dear Kua Coffee Drinkers,

We’re excited to announce that our coffees from our farming partners in Uganda, Zukuka Bora, have arrived and are tasting delicious. With this in mind, we thought we’d share a little about different coffee processing methods and how these can vastly impact how a coffee can taste. All of the coffee is grown in the same region of Mt Elgon, but processed in various ways to achieve unique flavour profiles. The producers selectively hand pick the best ripe cherry before the Zukuka Bora team deviates into one of the following processing methods. Kua Blue is made up of washed, natural and honey components.

Washed Process

The ripe cherry first has its flesh removed to reveal the coffee seeds inside - this is called pulping. The seeds are then placed into tanks and submerged in water for up to 48 hours. This fermentation allows the enzymes to break down the remaining mucilage leaving the coffee very clean in both appearance and flavour. The coffee is then dried slowly over a few weeks until it is dry enough to remain stable and not go mouldy. The last step is the dry mill, which removes the outer shell or parchment leaving the coffee beans ready to pack for export. Washed processing is very popular as it has an approachable flavour profile and is one of the lowest risk methods of processing. One of the downsides is that it requires lots of fresh water supply so isn’t possible for all producers. A washed coffee will have subtle chocolate and fruit flavours, bright acidity and floral aromas.

Natural Process

Natural processing has the least intervention, the coffee cherry is left intact and skips straight to drying. Leaving the fruit on while drying begins a natural fermentation process with the fruit becoming fuel for the enzymes to break down and impact the flavour of the seed inside. Drying natural processed coffee takes about twice as long and takes up twice the space as washed processed coffee, and is also one of the more risky methods as it has more time and opportunity to become mouldy or develop undesirable flavours similar to overripe fruit. Benefits of natural processing are the potential to dramatically enhance intensity of flavours and sweetness, potentially leading to a higher sale price. Natural processed coffees will exhibit intense fruit flavour and aroma, heavy body and higher sweetness.

Honey Process

Honey processing sits somewhere between washed and natural processing. It is a compromise for producers looking to have a cleaner flavour, though might not have access to water for a washed process and also want to reduce the risk of a fully natural process. It begins similarly to a washed process by pulping the coffee and removing the flesh, but instead of washing the coffee it is left sticky and dried with some residual mucilage. As expected this sits somewhere between washed and natural process drying time and the parchment turns a golden, honey colour as it dries. This is where the term honey comes from. Honey processed coffee often has a caramel sweetness, slightly muted acidity and some stewed fruit flavours.

Anaerobic Natural Process

A process taken from winemaking and adapted to coffee processing, anaerobic fermentation is growing in popularity and now widely available in specialty coffee. Anaerobic simply means to deprive oxygen during the fermentation process. In coffee processing this means sealing the coffee cherry in airtight tanks for extended periods of time. This environment encourages a more efficient metabolisation of the fruit by the microbes and results in a more intense version of the natural process. Once reintroduced back to oxygen the fermentation stops and the coffee continues the rest of the natural process. As the cherry is drying it looks darker and has a glossy skin compared to a regular natural process. Anaerobic natural process coffees have intense wine characteristics, sugary sweet and heavy body.

Coffee processing is ever evolving. These four processes are common examples but there are endless variations, for example, a black honey process is dried without turning, leaving the sticky mucilage to turn really dark, or anaerobic washed process where coffee is removed from the sealed tanks and then follow the washed process resulting in really bright and sweet washed coffees. The possibilities are endless, involving many other variables that impact flavour, like country, region, elevation, varietal, soil, fertiliser, rainfall and shade.

Happy days.

The Kua team