Coffee Processing Methods Explained : Natural, Anaerobic, Honey, Oh My!

Are you starting to get serious about specialty coffee? It’s essential that you learn about all the different coffee processing methods.

You know when you look at a bag of coffee and see “black honey” or “anaerobic natural”? Our aim is to help you end this head-scratchery so you can be confident about your coffee knowledge.

We did a previous blog about coffee processing before, but we wanted to revisit it more in-depth and add some newer processes to the mix. Understanding how your coffee was processed helps you understand why it tastes the way it does.

Natural Processed Coffee

What is coffee processing?

In a nutshell, coffee processing is what gets done to the coffee cherry after it’s been picked off the tree and sorted. After harvesting and picking the ripest cherries, the producer needs to decide what to do with the cherries.

Coffee is the seed inside of a cherry. Sure, you could simply remove the cherry and discard it immediately. That is a coffee processing method in itself (more on that later). But the cherry itself is sweet and fruity, and it can add some very interesting, complex flavours to the green beans.

In most forms of processing, a certain amount of the cherry pulp is left on the bean to ferment. Fermentation is a tricky task which can go terribly wrong and result in spoilage, but if done right, it can be magical. It requires getting the right temperature, pH level, and fermentation time.

Layers of a coffee bean

 

The anatomy of a coffee cherry

Let’s run through the anatomy of a coffee cherry so that when we throw around terms like “mucilage” and “skin,” you know what we’re talking about.

The skin or the “cascara” of the cherry is the outermost layer of the fruit.

The pulp refers to the overall flesh of the fruit, just under the skin.

The mucilage is a very specific part of the pulp–it’s the sticky, slippery layer that covers the seed.

The parchment is the papery layer of the seed that covers and protects the seed. It comes off naturally while being roasted.

The seed of the coffee cherry is essentially the green bean.

To better visualize the anatomy of a coffee cherry, check out this resource. 

Let’s run through the most popular coffee processing methods.

fully washed coffee

Wet process coffee

Wet process coffee, or “washed” process, is a process where the pulp and mucilage are removed from the seed as quickly as possible. 

First, the coffee cherries are placed in a de-pulping machine. Second, the seeds ferment briefly to soften the mucilage just enough to facilitate easy removal. Third, the seeds are soaked in water and agitated to remove the sticky mucilage layer. Finally, the seeds are laid flat on beds to sun-dry completely before being packed and shipped.

This is a very popular method of processing because it lends a very clean taste that allows the natural acidity to shine.

honey processed coffee

 

Honey process coffee

In the honey process, the skin and pulp are removed from the seed, but the mucilage is left on the seed during fermentation.

There are 3 different levels of honey process coffee: yellow, red, and black. The darker the colour, the longer the fermentation, and the stronger the flavour. Let’s explore these sub-processes more in-depth.

The mucilage is left on the seed, and the beans are laid out on large mats to sun dry. Yellow honey process coffee is lightly sweet and fruity with a clean profile, similar to wet process, but fruitier.

The mucilage-covered seeds are fermented slightly. The seeds are piled on top of each other to facilitate fermentation, and then raked into a flat layer to dry. Red honey coffee tastes sweet and fruity.

In this process, the mucilage-covered seeds are fermented the longest. The beans are piled on top of each other, with a longer fermentation than red honey. Black honey process coffee tastes winey and boozy thanks to the longer fermentation, with ripe fruit notes. 

 

natural processed coffee

Natural process coffee

Natural process coffee is where the whole cherry is left intact on the seed during fermentation. This includes the skin, pulp, and mucilage–nothing is removed. 

The beans lie in the sun on raised beds, while constantly being turned. This prevents rotting and spoiling the entire batch of coffee. Once the beans are fully dried, the dried cherries are hulled off to extract the green beans.

Natural process coffee has a very fruity, molasses-y flavour that a lot of people are drawn to. It’s common to taste fruity notes like blueberry, strawberry, and raspberry, with a pleasant acidity.

The natural process is popular in coffee-growing countries where clean water isn’t an abundant resource. You’ll tend to see natural process coffee from countries like Ethiopia where there isn’t a huge supply of clean water.

Anaerobic process coffee

The anaerobic process is a newer process that’s quite tricky and time-consuming. When done properly, it can have incredibly exciting, exotic flavours like tropical fruit and spice.

Anaerobic means “oxygen deprived.” The intact coffee cherries are placed in large barrels with water and sealed from oxygen for 48 to 72 hours. They ferment without oxygen, which imparts  a completely different flavour from natural or honey processing. After fermentation, the pulp and mucilage are removed and the beans are laid to dry completely in the sun.

Raised African Drying Beds

Wet hull process

Not to be confused with “wet process,” the wet hull process is a less common type of coffee processing. Also known as “giling basah,” this coffee process method is mainly practised in Indonesia. In this process, the parchment is removed from the seed before the bean dries completely.

Coffee that’s been wet hulled tends to have rich earthy, smokey, dirty flavours, with little to no sweetness or acidity. These coffees tend to taste good when roasted dark, which eliminates some of their unpleasant flavours. This allows the desirable flavours, like earth and smoke, to shine. 

Trust the process

Coffee processing methods have a huge impact on the flavour of your coffee. If you’re a coffee lover and want to learn more about coffee, it is essential that you learn about coffee processing methods. It can help you understand why your coffee tastes the way it does.

Want to experience coffee processes for yourself? Shop our Kenya Fully Washed, our West Coast Honey Processed, or our Gunsmoke Fully Washed & Wet Hulled coffees now!

 

The Effects of Drying Speeds for Green Coffee

Nothing is more rewarding then seeing a fresh crop of micro-lots being unloaded off the back of a truck into our roastery.  This pleases me so much as I know the amount of work our producers and exporters have put into this coffee to get it this far.  I also know how much work we have put into sourcing and choosing these precious beans to offer our clients.  What many don’t know, is how the drying speeds at the farm, can drastically effect the quality and shelf life of the green beans roasters receive.  

 

Nothing is more disappointing then when you begin to sample roast and begin profiling these new arrivals and the flavor profiles we tasted at origin are no longer being tasted.  “What is going on!?!?  How can a coffee taste so different at origin compared to what we are tasting now?”   This isn’t unique to Fratello, and is something we have heard many roasters around the world talk/complain about.  It has been a topic of many conversations over the past year with the coffee producers we work with and exporters who are working on the ground at origin every day.

My first major experience with this coffee was 2 years ago when we purchased an incredible micro-lot from Acevado Huila, Colombia.  This 20 bag lot was scored a 91.00 at origin by myself and the others we were with that day.  It was an outrageous coffee, and we paid top dollar for it.  By the time we received this coffee 3 months later, it was extremely faded.  We were getting cupping notes of wood/twigs and it almost tasted like a past crop coffee.  The moisture content was accurate and the processing seemed perfect.  We ended up not selling this coffee to anyone.  It was a total waste of our time and re-sources.  So what went wrong?

6 months later we visited this coffee producer again and began asking questions about how they dried their coffee.  In Colombia it is normal for producers to use a Parabolic drying bed (similar to a green house).  These are perfect for protecting the green beans from the elements; however, it can also produce high levels of heat when not used properly.  Unfortunately, this producer was not, and was drying their coffee in 3-4 days.  This is WAY too fast.  Typically, a producer would want to slowly dry their coffee over a 12-18 day time frame for an even consistency throughout the bean.    What we are learning is when you dry your coffee too quickly; it is hard to read the correct moisture level in your green beans accurately.  The extreme heat forces the water content into the beans giving a false reading in your moisture meters.  You may show a moisture reading of 11-12% (which is the goal), but as these beans sit, the moisture that was forced into the bean, will migrate back out to the surface over time.  The end results are beans being pulled from the drying beds much to early, giving an unstable bean, which has potential fermentation and accelerated fading in flavors.

Another example is in El Salvador we had purchased an award winning Pacamara (large bean).  It was extremely sweet, with an orange syrupy body, maple flavors and very clean.  On arrival in Calgary, we found some of the same faded, twiggy notes coming through in the cup.  Again, a huge disappointment.  With research we found that the drying time was 5-7 days, which was much too fast for such a large bean.

In speaking with our producers the biggest challenge they face is the changing environment.  It is getting hotter and more intense each year.  They never had these issues in the past of drying the coffee this quick and now have to re-think their processing techniques.  Creating systems that help them slow the drying times employing shade barriers and different cooling techniques.  All of this takes time and often a lot of money to re-create their drying beds.  More and more often we see raised African beds with shade cover being installed and used on our top micro-lots.

This then brought my attention to the mechanical drying systems installed at MANY large and micro-mills around the world.  They are becoming very common, as coffee must be dried once it is de-pulped after harvesting.  If the sun isn’t out due to rain, the coffee will need to go into dryers.   These dryers work very fast, and often only take 1 day to finish the drying.  This drying technique is not only fast; it consistently dries the bean through out.  Is this the best route?

Studies are now showing that the ideal drying conditions for coffee require the slow drying technique.  What this allows are some resting periods for coffee.  When heat is on the beans, the cellular structure opens, when the temperatures drop, the cells close…. almost like it is breathing.  This has shown to create a harder cellular structure on the bean that enhances acidity and gives better conditions when roasting.  The fast drying speeds in the mechanical system never allow for resting, giving a softer cellular structure and less acidity in the final cup.

This short blog post barely scratches the surface on drying techniques and does not answer or explain everything processing technique (Naturals, pulped naturals, honey’s, etc…), but has simply been written to bring some awareness to a subject not often discussed.  We have some much more to learn, and together with the producers will continue to push the limits of processing, exporting and roasting the best coffee in the world.

Coffee Processing: What gives coffee unique flavors?

harvesting red coffee cherries

This is an interesting question, and one that does not have a quick answer.  I often compare coffee to wine as there are many comparables.  All bottles of red wine from Italy do not taste the same.  It is dependent on the vineyard, the grape (Merlot, etc..), the harvest, soil conditions, altitude, weather conditions of that particular harvest in that particular year, in that particular region.  All of this is also true with coffee.

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