• Coffee Processing Methods

It takes several years for a single tree to start yielding the fruit, months for the fruit to get ripe, weeks to process the coffee seeds and get them shipped to your country. Even then, more time will be spent developing the perfect flavour profile so that the customer can enjoy a cup of coffee for a minute or two.

 

coffee bean processing from cherry to green coffee

from 'cherry to 'green coffee'

 

When buying coffee from a speciality coffee roaster, you will definitely find a note about the method used to process the beans. Natural, Washed, Honey or Pulped Natural processes are the ones you most likely to see on the coffee packaging. 

 

Of course each farmer/ washing station will have a unique way to process coffee beans, but to be able to understand coffee processing approaches we must first understand the fundamentals of them.

 

coffee cherries after they've been picked

coffee cherries after they've been picked from the trees 

 

The process the farmers choose for the particular crop of their coffee will depend on many variables. The desired cup profile they would like to achieve as well as the climate conditions in the place they live and the cost of the processing method. Sometimes, decisions have to be made purely due to the availability or otherwise of enough water. 

 

a coffee picker with her haul

 

The natural process also called a dry process originated in Ethiopia and is most common in countries with less available water. After harvesting, ripe coffee cherries are separated from the unripe ones.

 

natural processed coffee drying

 natural processed coffee drying on a patio

 

In the next step coffee cherries are dried on patios or raised beds. The cherries must be turned regularly to control the inevitable fermentation as this could cause some unpleasant qualities in roasted coffee.

 

coffee drying on raised beds

 

coffee drying on raised beds

coffee drying on raised beds

 

Although the natural processing method may look like it needs less investment it still needs a lot of attention from the farmer as well as certain climate conditions. When properly dried and stored, natural processed coffee will enchant you with rich sweetness, heavy body and a taste profile of juicy tropical fruits or summer berries. Well controlled fermentation can also impart a boozy element to the coffee. 

 

The washed process or so-called wet process, focuses on the bean itself and the amount of sugars and other compounds that are absorbed by the seeds from the cherry. After harvest, the ripe cherries are separated from the unripe ones which can be done by hand or in a floatation tank and (with a machine called a de-pulper) most of the cherry mucilage and skin is removed.

   

a coffee de-pulper

 

coffee de-pulper

coffee running through a de-pulper

 

The coffee beans are then moved to a tank with water where the fermentation process begins. Fermentation time is very important and usually takes between 12 to 72h.

 

coffee drying

 

washed coffee drying

washed coffee drying

 

Once fermentation is done, coffee seeds are washed to remove any remaining fruit flesh and then dried on the brick patios or raised beds. This process is very common in the speciality industry as when stored and roasted properly such a coffee presents complexity of flavours, high acidity and clean profile.

 

pulped natural coffee

 pulped natural coffee

 

The Pulped Natural process or ‘honey process’ (for our purposes, these methods are similar enough to be considered together) is in some ways the best of both worlds. The coffee beans take the rich sweetness and body of the natural process, a round acidity and clean mouthfeel from the washed process. It uses less water than in a wet process which is more environmentally friendly.

 

Once harvested ripe coffee cherries undergo the de-pulping process but instead of removing all of the fruit flesh the machine leaves some of the mucilage on the coffee seeds. Less flesh on the coffee seeds decreases the risk of unwanted fermentation during the drying process-  an advantage over natural processing methods in this respect. Following the de-pulping process, coffee is dried on patios or raised beds.

 

coffee drying

coffee drying 

 

Although these three methods start differently, they meet at the drying point in the same place. The next steps relate to all the above processing methods. Once coffee beans have reached the desired moisture content, they are moved to special containers to rest.

 

coffee with parchment attached

 coffee beans with parchment attached

 

The next step is hulling where the coffee parchment is removed - coffee parchment plays a protective role while coffee is resting.

 

sorting and grading coffee

 coffee being graded according to size

 

Once beans are hulled, the grading process can begin, which will be either done by a machine or by people (usually female workers). Grading is a very important stage as any visual defects can be removed, which will lead to an increase in lot quality. 

 

Still, in most of the coffee origin countries grading is based on the size of the coffee bean which is checked by using special screens also called sieves. The largest beans in size are considered the highest quality which is also addressed in the price of it. Although this system is the most common one, coffee beans will also be classified in relation to their colour, defects, moisture content, density age and a cup score.

 

I hope you’ve enjoyed this brief introduction to coffee processing methods. Next week we are going to dive into the subject of coffee species!...but just before that, here are a few video clips of what we have been talking about here. Enjoy! 

Magdalena.