What is coffee processing?
You may have heard of washed coffees, natural coffees and maybe even honey processed coffees. But what does coffee processing mean?
In this blog post we explain some of the most common processing terms that you might come across on labels and info sheets in the world of speciality coffee and how the way your coffee is processed could change how it tastes in the cup.
It’s a long one, so we recommend sticking the kettle on and making sure you’ve got your favourite brew to hand before getting stuck in.
What do we mean when we say coffee processing?
In coffee we talk a lot about different processing methods. in particular washed coffees like Dr Strangelove Espresso, natural coffees like our summer espresso, Funka and honey-processed coffees like our limited edition, Inner Strength Espresso.
But what does all this mean?
In short, processing is the journey that coffee makes from being a bright red coffee cherry (a fruit) to a green bean ready for roasting.
Just like origin, roast profile, soil climate and varietal, how a coffee is processed has a huge impact on the final taste of the coffee in the cup and how the quality of the coffee is judged.
Most speciality coffee is priced according to quality. Coffees of a higher quality, with few defects and complex, interesting flavours score higher when graded and therefore fetch a higher price.
Usually, this price is far higher than organic or Fairtrade premiums. Speciality coffee producers and mills therefore take great care in harvesting, sorting and processing their coffee to reach the highest possible score at grading.
If you're interested in trying a wide range of new and different coffees, you might want to consider our Roaster's Choice Espresso or Roaster's Choice Filter Subscription.
With these subscriptions, our Head Roaster, Tommy selects a different coffee for you to try each month.
It's fun and a great way to explore different processing methods, varieties and origins to find out what sorts of coffee you enjoy the most.
What is coffee sorting?
Specialty coffee growers are meticulous about the sorting of their coffee.
Farmers will pay a premium to skilled pickers who can ensure that only perfectly ripe red cherries are harvested.
Higher quality coffee with few defects can be sold for much higher premiums, so investing in harvesting and sorting will impact the final score and price that a grower can expect for their coffee.
Once harvested the coffee is sorted.
This can be done by hand, or sometimes density in flotation tanks where poor quality cherries float to the surface and are removed from the lot.
Below, you can see coffee being sorted by hand by farm workers in the Coopade Cooperative in the Democratic Republic of Congo and coffee being sorted in flotation tanks at the Mutira Coop in Kenya.
Coffee in flotation tanks being sorted by weight at Mutira Cooperative in Kenya.
Once coffee has been harvested and sorted it will be processed.
Usually coffee is processed in one of these three ways: washed process, honey process, and natural process.
These three methods are distinct and all have an impact on the final flavour of the coffee you enjoy at home.
What is washed process coffee?
The washed or fully washed method is the most common way of processing coffee. It’s also the most water intensive.
Washed coffees are popular for their uniformity, and for the fact that they're well balanced with clean, bright flavour notes. At Extract, we use washed coffees in several of our blends, including: Original Espresso and Rocket Espresso.
Washed coffees aren't just for house blends though. Their delicious, easy-drinking flavour profiles mean that they're also popular for single origin coffees such as Dr Strangelove Espresso, Cast Iron Espresso and Los Huipiles Filter coffee.
So, what does the washed process entail?
Ripe red cherries are picked and then sorted. This can be done by hand or by density in flotation tanks.
The sorted cherries are pulped to remove the skins from the cherry, then washed to remove the sticky mucilage from around the bean.
Finally the coffee is dried.
This could be in mechanical dryers, on tarpaulin or patios on the ground or on African raised beds.
In the photographs below you can see washed coffee drying on raised beds in the Democratic Republic of Congo, coffee drying on a tarpaulin in Peru, and coffee drying on a patio in Cauvery Peak, India.
Some producers add a fermentation step into the washed process, fermenting the coffee cherries in fermentation tanks before removing the fruit of the cherry.
We go into more detail about the different types of fermentation that a producer might use later on in the blog post.
The photo below was taken when Dan and Ben from Extract visited Chania Coffee Estate in Kenya and shows washed coffee beans.
Washed coffee photographed at Chania estate in Kenya.
What is honey process coffee?
Honey process coffees are known for an intense sweetness, and also for their golden colour as they dry.
Honey isn't actually used at any stage of the process. They're named for the sweetness and colour.
We really like the complexity that this processing method brings to a coffee with interesting fruit flavours and lots of sweetness, but not too much booziness.
Our 2023 Inner Strength Espresso is a red-honey micro-lot, produced exclusively for Extract Coffee Roasters.
This coffee came about after Extract visited Finca Valentina in Honduras and Head Roaster, Tommy, spoke to farm owner Carlos about how he'd love to try one of their coffees processed as a red-honey.
One year later, here we are, an incredible coffee processed just for us.
The photos below are from Tommy and Harrison's trip to Honduras and show them looking at coffee cherries on the farm and tasting different coffees around the cupping table.
This particular coffee is an incredible example of the sort of complexity and delicious fruit flavours which are typical of honey-processed (in this case a red-honey-process) coffees.
Think dark cherry fruit notes, with almonds and honeycomb sweetness. Yum!
In the honey process, the coffee cherries are picked and sorted (either by hand or by density in water).
The cherries are pulped to remove the skins, leaving behind the sticky mucilage (fruit) of the cherry around the coffee bean.
Instead of washing the sticky fruit (mucilage) of the cherry off the bean, the coffee is left to dry with the fruit intact. Coffee can be dried on raised beds, patios or in mechanical dryers.
As the mucilage of the coffee dries, it imparts sweet fruit flavours into the coffee (this is where the name honey process comes from).
Honey-processed coffee is often categorised according to how much fruit is left to dry around the bean. How much fruit is left on the bean has a huge impact on flavour. We explain a bit more about the different types of honey processed coffee below.
During the drying process the coffee is turned or raked over to ensure even drying and to control the humidity of the coffee as it dries.
In this photo, from Finca Santa Teresa in Panama, you can really see the golden colour of this honey process coffee as it dries.
Honey process coffee at Finca Santa Teresa in Panama.
Once dried, the coffee is dry-milled to remove any remaining fruit or parchment from the beans. The final step is sorting and grading the processed coffee. Brazilian coffees processed in a similar way are known as pulped-naturals.
As well as single-origins and micro-lots, like Inner Strength, honey-process coffees also feature in some of Extract Coffee Roasters' blends and house-espressos, such as Original Espresso and Organic Espresso, for example Liquidambar Espresso.
What are the different types of honey process?
Honey process coffees are often categorised by colour, these refer broadly to how much of the mucilage from the coffee cherry is left around the bean.
Black-Honey Processed coffee: Black-honey processed coffees are pulped and the majority of the fruit of the coffee cherry is left intact.
Red-Honey Processed coffee: A red-honey processed coffee is pulped to remove the skins, then dried with around 50% of the mucilage intact. Our Limited Edition Winter Espresso, Inner Strength, is an exclusive red-honey micro-lot which was produced for Extract Coffee Roasters after we met farm owner, Carlos in Honduras in 2022.
White-Honey Processed coffee: A white-honey processed coffee is pulped, then most of the sticky mucilage is removed, leaving just a small amount of fruit to ferment around the bean.
What is natural process coffee?
Natural process coffees can be pretty divisive. They're known for their sometimes boozy flavours, intense fruitiness and complex tasting notes. Whilst many coffee lovers adore natural coffees for their unique taste (ourselves included) for some, it's a step too far.
In a blend, a natural coffee can bring an interesting fruit note and sweetness. A great example of this is our Half Speed Low Caffeine Espresso which is a blend of a natural, a washed and decaf coffee.
Many coffee lovers enjoy natural processed coffees as a single origin, where their unique profiles can really shine. Los Altiplanos is a natural filter coffee from Nicaragua with cola bottle flavour notes!
Each summer the team at Extract Coffee Roasters set ourselves a challenge to find the funkiest natural we can and roast it as our mouthwatering summer espresso, Funka.
Natural process coffee is the least water intensive method. Ripe cherries are picked and sorted, then left to dry usually on patios, tarpaulins or African raised beds but sometimes they could be dried in kilns or mechanical driers.
The fruit of the coffee cherry dries, it ferments around the coffee bean, imparting intense fruit flavours and sweetness as it does so. The fermentation process may also impart a boozy note into the final taste of the coffee - so it’s not unusual to see natural coffees with flavours like brandy or sherry in the flavour notes.
The humidity of the coffee is monitored closely as it dries. Coffees are turned and raked over throughout the process. Any sign of mould or over-fermentation could be disastrous and result in the producer losing the entire lot. The complex flavours which develop as a result of natural processing can have a huge impact on the score the coffee receives in grading - so it’s a case of the coffee grower or mill balancing risk with reward.
In the photographs below from Finca Santa Petrona in El Salvador you can see the coffee cherries intact as they begin the drying process.
The second photograph shows coffee a little further along in the drying process on raised beds at the Chania coffee estate in Kenya.
Natural processed coffee cherries at Finca Santa Petrona in El Salvador.
Natural processed coffee on African raised beds at Chania estate in Kenya.
What about other types of coffee processing?
There has been an increasing amount of words added to the "processing' section of in competitions, on coffee bags and cafe menus over the past few years. Words like maceration, anaerobic, carbonic, extended fermentation and thermal shock are all becoming increasingly common.
The team at Extract Coffee Roasters are still trying to understand what they all mean in practice. Whether these new terms and processing methods are adding to the experience for drinkers, for baristas and roasters and if they actually add value to the producers.
So what do these actually mean and how they differ from the three main coffee processing methods?
Some of the terms used to describe coffee processing are borrowed from other industries - wine in particular which uses fermentation to influence a fruity drink so the connection is logical, even if the results aren't.
Few people have been able to succinctly explain what each term means and the results are somewhat inconsistent.
This isn't surprising as each farmer will be doing their own version based on experimentation, advice and feedback and these are all influenced by the coffee they start with as well as naturally occurring microorganisms and the environment they work in. A lot of variables.
We're not vinters, or microbiologists so we can't give you all the answers but we will try and get you a little closer with the little we've learned so far.
Ripe fruit contains sugars and sugars can be manipulated by bacteria, yeast, oxygen and heat in particular.
The newer processing methods use these four elements to affect the flavour and complexity of the coffee by speeding up or slowing down fermentation process.
Here's how this works.
Bacteria consumes sugar, breaking down the pectins and leaving acidic secretions.
Yeast also consumes sugar, and different yeasts eat different sugars at different rates. Some sugars are inedible to certain yeasts (think lactose in beer, milk stout remains sweet rather than fermenting into more alcohol or Co2). Yeast secretes alcohol and carbon dioxide.
Oxygen allows both bacteria and yeast to live and so by restricting it, you restrict its growth and outputs. Like us, without any they will die.
Heat has an impact on both bacteria & yeast which have ideal operating temperatures. Too low they will mostly go dormant, but not die. Too hot and they will die. Different heats will have different preferred temperatures and growth will become rapid as well as producing different types/flavours of alcohols.
Now that we've got these basic principles covered, let's dive into some of the more experimental processing methods.
What is anaerobic or semi anaerobic coffee processing?
Anaerobic fermentation refers to coffee which has been processed without oxygen. Typically the coffee cherries are pulped to remove their skins and then placed in an airtight sealed tank to ferment. (how long is decided by the coffee producer).
Semi-anaerobic fermentation follows a similar process but in this case oxygen is present, but in a reduced supply.
Without little or no access to oxygen there are only a few, very specific microbes which can survive during the coffee's fermentation process. The result is that coffees processed in this way develop unique and complex flavour profiles.
Last year Extract roasted a semi-anaerobic fermentation filter coffee, Finca Capri with notes of black jelly babies, papaya and plum. These complex flavours help the coffees score highly in grading and make them popular in coffee competitions too.
What is maceration coffee processing?
Maceration, often Carbonic Maceration, in wine means leaving skins in contact with the fruit, which is usually crushed to release the juice. This allows the tannins and colour pigments, anthocyanins, to combine with the juice.
In coffee we are seeing some producers leave cherries intact, no crushing, but others lightly crushing or loosely pulping the cherries and then leaving the skins in contact, similar to how some pulped natural coffees are processed in Brazil.
The carbonic part can be caused by the naturally occurring CO2 being trapped or by introducing bottled CO2 much like we do with nitrogen in our bags.
This is done to reduce the rate of fermentation (starving the bacteria & yeast of oxygen) Grain pro bags, plastic barrels and tarpaulin covered fermentation tanks are all being used.
What is extended fermentation coffee processing?
Extended fermentation is one of the more common techniques used in coffee processing to add complexity to the flavour of the coffee.
Extended fermentation loosely means pushing the fermentation longer than usual, and usual will vary hugely from farm to farm, mill to mill.
The producer manipulates and is all impacted by the local conditions for bacteria, yeast, heat, oxygen to slow down the fermentation process. It is thought to develop more complex fruity flavours without allowing off flavours to develop.
Some of Extract's oldest coffee partners, for example Veracruz coffee farm in Colombia, use an extended fermentation process to give their coffees such a unique flavour.
What is controlled yeast coffee processing?
Controlled yeast has been used in alcohol production for most of the 21st century to, well, control which yeast is able to grow and ultimately control its impact on flavour.
Historically this wasn't the case and the resurgence of 'natural wines' is bringing back the diversity of local yeasts to the world. For those who have tried them you will know how variable they can be. This is where we are at with all coffee but especially natural coffees.
There are a small number of coffee producers now using a controlled yeast which will outgrow any locally occurring ones and with a little temperature and moisture control enable the producer to replicate the same levels of fermentation (in washed, honey or natural) coffees again and again - as long as they buy the same control yeast again.
What is thermal shock coffee processing?
Thermal shock coffee processes uses hot and/or cold water, sometimes in succession at various temperatures, to halt and limit the growth of the yeast or bacteria, slowing down and fermented flavour development and allowing the coffee to remain at that level for prolonged periods.
This happens naturally in every coffee farm every night - hot days cool nights - and coffee is picked throughout the day, processed in the afternoon and often ferments slowly overnight anyway.
What isn't usually controlled is how warm it gets the following day. With thermal shock, the farmer is manipulating this process to influence the final taste of the coffee.
A couple of years ago we chose a thermal shock coffee with wild flavour notes of plums and candied sweets as our Christmas Sugar Plum Filter. Delicious.
Coffee processing? Completed it mate!
You made it! A huge thank you to all of the coffee lovers who stayed with us to the very end of this blog post. We hope this helps you to understand some of the terms being used and why.
It seems to us that the variety of processing methods now available is good for coffee drinkers, baristas and enthusiasts - creating interesting flavours in the cup, but also for coffee growers, who benefit from less spoilage, higher scores and prices for their coffee at grading and a reputation for innovative coffee production.
All that reading left you thirsty?
Check out our latest selection of coffees available to buy online.