The journey of a coffee bean from crop to cup is one fraught with more variables than your average science experiment.
For a start, there’s the genetics of the bean, and that’s before you get to the environmental and geographic factors like altitude, soil and climate, which can imprint onto the taste of the bean with the same permanency of a tattoo.
More than just genetics and growing conditions, there are processing techniques, which happen after the bean is picked and leave their own taste in your mouth. Round up all of these variables, and you can see why they call it ‘the science of coffee.’
Discover why no two coffees taste the same with this wrap up of processing techniques, and how they affect your favourite coffee’s flavour.
First things first, what is processing:
Once the fruit is picked, the farmer can still affect the flavour in his own way by applying different processing methods.
The coffee fruit resembles a ripe cherry, with a hard outer case that contains two green seeds, the coffee beans.
To protect the precious bean-cargo, the fruit encases the beans in a sticky substance called mucilage and the cherry’s skin, which cocoons the beans from the elements while they’re growing.
The method used to remove the fruit and mucilage layers is called ‘processing’, separating the green coffee beans from the fruit.
1. Natural / Dry Process
It’s no surprise that the most traditional form of coffee processing is ‘natural’, favouring climates with a distinct wet and dry season, which suits most coffee-growing districts of the world.
You’ll find this format of processing most commonly done in Brazil, Yemen and Ethiopia, where farmers dry out the coffee fruit for up to three weeks in the sun.
Once picked, the fruit is dried with the seeds inside it, to reduce the moisture content within them.
This process is far from being a set and forget - the farmer needs to constantly monitor the fruit, turning it every few hours to ensure it dries evenly and to ensure that the fruit doesn’t over-ferment, rot or go mouldy.
Once dried, the fruit and mucilage layers can be removed by machine, leaving the green coffee bean ready to be bagged and exported.
As a coffee drinker, you’ll find that natural processing generally delivers low-medium acidity, heavy body and thick, fruity sweetness, noticeable even in the cup.
2. Fully Washed / Wet Process
The clue is in the washed-processing method’s name. Here, the beans are processed using water to remove the mucilage from the bean.
Processing by washing coffee is equally as popular as natural processing, but far less risky than natural processing when it comes to changing the bean’s flavour profiles.
Instead, the coffee fruit is picked and taken to a machine called a ‘de-pulper’. Here, the machine removes the outer layers of fruit, revealing the beans.
The beans are then sent to fermentation tanks with their mucilage still on, where they are submerged in water and the washing begins.
The length of time that the coffee spends in fermentation depends on altitude, temperature and desired outcome - another variable to an already complex process behind your coffee’s journey from crop to cup.
Generally washing takes 18-36 hours, however this depends on the farmer’s methods, water availability and desired flavour outcome.
Washed coffees generally have a medium to high acidity, lower body and crisp, clean flavour.
3. Semi-Washed Process
Brazil is the pioneer of the semi-washed method of processing coffee.
Through this process, coffee cherries are de-pulped, then placed in fermentation tanks for only about four hours, after which the beans are then dried on raised beds or patios.
Throughout this process, the mucilage is partially removed, compared with fully washed which removes all the mucilage at the get-go.
The extra mucilage delivers additional sweetness and body to the coffee, and some fruity elements as well - flavours that don’t need a coffee connoisseur’s trained palate to pick up.
4. Honey Process / Pulp Natural
The honey processing method is as sweet as it sounds - found in Brazil, Guatemala, Costa Rica and El Salvador to name a few.
This processing technique is similar to the natural process, except that the skin layer is removed first, so the coffee is laid out to dry with the mucilage still intact.
Some farmers control the amount of mucilage left on the fruit with machines called ‘de-mucilagers’ that remove part of the mucilage layer.
This process tends to exhibit tremendous sweetness and fruit quality in the beans, without becoming murky as can happen with natural process coffees.
5. Monsooned Process
Monsooning is a rare process that’s applied to some coffees originating from the coastal Malabar region of India.
This is an ‘additional process’ that was created to replicate the conditions once found on board ships sailing from India to Britain in the times of the British Raj.
Back then, the journey would take 4-6 months and the coffee on board the ship was exposed to the moisture and sea air, which would mature the beans in a completely different way to air drying.
With the invention of planes and modern cargo ships, consumers noticed the coffee lacked the familiar flavour of the voyage, and so the monsooning process was created to recreate that flavour profile - and the Monsoon process was born.
Through this method, coffee is fully washed and dried in the traditional way. It’s then stored away in warehouses until the monsoon season approaches.
At the onset of the monsoon, the coffee is spread out in large open sided warehouses, so that they can be exposed to the humidity and ocean winds brought by the monsoon.
After 12-18 weeks, the beans will have achieved their light golden colour and the monsooning process is complete, replicating the flavour of a six month journey from India to Britain.
If you’re lucky enough to taste coffee that was processed with the monsoon method, expect a drop with a flavour profile that’s earthy, spicy, herbal, and scented similar to cedar.