What is Coffee Processing?

When buying coffee we see a lot of words like; natural, washed, fermented and anaerobic. But what do they actually mean?

Coffee starts it's life on a tree, like many fruits.

   

Once picked, the coffee cherry has to go through processes to remove the layers surrounding the bean.

There are many layers before you get to the good stuff inside.
These are;
- skin
- fruit
- mucilage
- parchment

   

There are so many processes for coffee, which all make a difference to the taste of the final cup.

All coffee gets fermented, but the length of time for the fermentation varies for each different process. Fermentation will even begin as soon as a coffee is picked due to the presence of water, sugar, bacteria, and yeast.

We will talk about the processes that the beans we roast have gone through.

Natural

The natural process is the oldest way of processing coffee after picking the cherries. This way of processing is only really common in countries and regions where water is not readily accessed, or in short supply. Such as; Brazil and Ethiopia.

Rather than removing the outer layer of the cherry, natural coffees are dried whole. This means that the bean absorbs and takes on some of the taste characteristics and sugars of the fruit itself.

Before getting emptied onto the beds the beans will be floated in water and sorted, to remove any unripe fruits.

   

Once the cherries are spread out on the patios or raised beds, they will get raked and shuffled around every so often to ensure the cherries drying don't go mouldy or rot in the sun.

At this time, beans can be naturally fermented too, which is another process of coffee. It is quite risky as too much fermentation will really hinder the flavour and quality of the bean.

    

Once at the correct moisture level and dry, the cherries are sent to be hulled. This is where the outer skin and fruit are separated to get to the coffee beans inside.

The cherries are then dry milled to get rid of all the fruit and husk remnants.

Our current natural coffees are from Honduras and Guatemala.

We also have a naturally fermented coffee from Brazil.

Washed

This processing method is quite similar to the natural, where the coffee is picked and dried. However before being set out to dry on the beds or patio the cherries go through a depulper to separate the cherry from the bean.

After being depulped the beans will still have the mucilage on them. This is the sugary, sticky layer before you get to the bean. The mucilage plays an important role in the drying process as it releases the sweetness into the coffee bean during fermentation.

The fermentation process happens over a few day, the beans are soaked in water with the mucilage present.

     

After fermenting the beans are then washed with clean water to get rid of any excess mucilage and then sorted onto a drying parchment, raised beds or patio.

     

Depending on the country or region the beans are either sun-dried or mechanically dried. Once beans are at an optimum moisture level, this process is complete.

This is one of the most popular processes, it often gives the coffee a clean, crisp and medium bodied profile.  

You can visit our online store to find our washed beans from Rwanda, Honduras, and Kenya.

Anaerobic

Anaerobic basically means without oxygen, so this coffee has been fermented in an environment without air. Sealing the coffee without air encourages the microbes needed for fermentation to consume all the oxygen quickly.

       

In the oxygen-less environment, the microbes that typically breath oxygen have a harder time surviving and those that flourish on carbon dioxide are able to dominate fermentation.

Carbon Dioxide (CO2) is produced in this sealed environment by the microbes breathing the remaining oxygen.

The fermentation can take place in cherry or de-pulped in the mucilage. The coffee then goes through the first process before being anaerobically fermented.

Our Ethiopia is an anaerobic natural, so we will be discussing the process the Chelichele washing station uses.

       

Selected fully ripe cherries are tightly packed into GrainPro bags and sealed shut. This can also be done in stainless steel containers and tubs where oxygen can be removed.

         

Fermentation without oxygen typically lasts between 18-24 hours. After this time the cherries are removed from the bags and laid to dry in direct sunlight on raised beds.

       

The cherries are then raked and turned over frequently to make sure they are drying evenly. This can take up to 3 weeks for the cherry to be dry.

Other Processes

There are many other coffee processing methods such as;
- Honey Process
- Carbonic Maceration
- Aerobic
- Wet Hulled
... and many more.

Farmers are always experimenting and coming up with new ideas to get the best flavour profile out of their beans.

Decaffeinated Coffee

As we all know coffee is quite highly caffeinated, but how do you make coffee decaffeinated in the first place?

Four of the most popular decaffeination processes are;
- Direct-Solvent Process
- Indirect-Solvent Process
- Swiss Water Process
- Carbon Dioxide Process

         

All of these happen while the beans are still green and before the coffee reaches roasteries.

Decaffeination is often associated with less flavourful because it is a bit tricky to remove only the caffeine and not any of the numerous flavour chemicals, and also decaffeinated beans are quite difficult to roast properly.

The decaf beans that we roast are from Colombia and are decaffeinated using the Swiss Water Process. The coffee is picked and processed like any other coffee bean before being sent to Swiss Water in Vancouver.

       

The Swiss Water process is an organic, and 100% chemical-free option for decaffeination. It was discovered in the 1930s in Schaffhausen, Switzerland, and was commercialised by the Swiss Water Decaffeinated Coffee Company Inc in 1988.

A main component of the Swiss Water Process is the Green Coffee Extract (GCE). This is created only once by soaking green coffee beans in pure water.

Before the decaffeination process can begin, the green coffee is rehydrated to prepare for the target moisture level, which is ideal and necessary for caffeine removal.

             

GCE is circulated around the green coffee for up to 10 hours, until there is no more than 0.1% of caffeine left in the green coffee. The caffeine is then filtered out through a carbon filter system, the carbon is sent to a regeneration furnace to burn away the caffeine so it can be used again.

As mentioned, the GCE is only created once, this is because each time beans are but through the decaffeination process the GCE is constantly getting refreshed and renewed.

                             

This completes the decaffeination process and the cycle can start again!