Coffee Processing Methods

The three main coffee processing methods explained

If you are passionate about coffee and want to know more about coffee production methods, what happens after harvest, this article will give you some answers. How is coffee processed after harvest? After the harvest, before coffee can be roasted and brewed, it needs to be processed. There are three main methods for processing coffee.

Here we will explain these three main techniques of coffee processing. We will describe what happens during each type of process and how it can impact the coffee taste and quality to help you make better choices and find your favorite type of coffee beans. But first, let’s specify what the term ‘coffee processing’ means. 

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What does coffee processing mean?

Coffee processing means separating the coffee seed from the coffee fruit, it’s the stage of preparation of coffee fruits for roasting. It’s the step between the harvesting of the cherries and coffee beans roasting. There are different ways in which coffee is processed, but the principle of coffee processing is to remove the cherry from the seed. 

What are the different ways to process coffee?

There are three main coffee processing techniques: 

• wet processing (washed processing)
• dry processing (natural processing)
• honey processing (pulp natural)

What are the differences between these methods? The differences between the coffee processing methods are related to when and how much of the fruit is removed from the seed, as well as how much fermentation the beans go through. Let’s look into more details about each coffee process. 

Washed vs natural vs honey coffee processing

Now we will describe each type of process: washed, natural and honey.

Wet coffee processing (washed processing)

What is wet coffee processing? 

Although there are different variations of the wet coffee processing, the main principle is that the coffee cherry is removed from the seed at the beginning of the process. The washed process is the most popular coffee processing method used around the world these days. Here is a brief description what happens step by step in the wet coffee processing:

Example of the washed process

These are the washed processing steps:

• Coffee is picked ripe by hand (only the ripe cherries are picked)

   

• The cherries are rinsed and sorted. In the rinsing tank the cherries which float on the top of the tank are scooped off and removed, as this is a sign of defect.

   

• The coffee fruit is separated from the coffee seed as soon as possible after the cherry is picked (usually between 8 and 12 hours from the harvest). This is done in a depulping machine, the machine squeezes the seed out of the cherries.

   

• After depulping the sticky mucilage is removed and the beans soak in a fermentation tank overnight. (A possible variation at this stage is that the coffee is left without water – this is called open fermentation).

   

• The next day the washing continues, the tank is filled with fresh water and the coffee is agitated regularly to remove the mucilage. Water may be replaced several times until the beans aren’t sticky. Any floating seeds are scooped and removed. At this stage the parchment layer still remains on the seeds.

   

• After the washing, coffee is moved to a sorting table where any remaining husks and defective beans are removed.

   

• Next, coffee is dried in its parchment. The seeds are placed on a drying surface (it can be on tarps or on raised beds), often under a roof. The seeds are dried until they reach 11% moisture content, which can take 1 to 2 weeks depending on the weather. At that time the coffee needs to be raked regularly to air the seeds.

   

• After drying, the coffee is sorted again.

   

• Finally, parchment is removed and the coffee is ready for shipping.

There are different variations of the washed processing but the principle remains the same. 

Fermentation in the washed process

An important part of the washed coffee process is fermentation. There may be different levels of fermentation coffee goes through and this will significantly impact the flavors in coffee. 

Is there anything added to the water for fermentation?

It depends on the producer, but yes, there can be various things added to the water during the fermentation. Those things can include:

• Enzymes
• Yeast
• Inoculum (adding of bacteria)
• Hot water
• Sugar cane (it has its own yeast which can speed up or slow down the fermentation) 

What type of coffee does the washed process produce?

The washed processing gives a cleaner product and a cleaner cup of coffee as compared to the dry process. 

Are there any disadvantages of washed coffee processing?

Yes, the washed process is more expensive than natural processing, as it requires expensive machinery and water treatment. Unfortunately, the washed process is also detrimental to the local environment, as the waste water after fermentation is highly acidic, contaminates the soil and rivers (it’s often disposed of to the local rivers). 

Where is the washed process used?

The wet method is used in climates with lots of sun during the day and cool temperatures at night. It may also be used on farms where there isn’t a lot of space available for drying. 

It’s used in many countries around the world, in parts of Africa as well as most Central and South America.

Dry coffee processing (natural processing)

What is dry coffee processing?

In the natural coffee processing the coffee fruits are dried fully intact. The seed, the fruit and the skin are kept together. 

The dry process, also called natural, is the oldest method of removing the coffee seed from the cherry. It originates from Ethiopia and is used in dry sunny regions. What’s interesting, this method is often compared to red wine processing. 

In the natural process the coffee cherries are usually dried on beds (drying over the ground prevents them from going moldy). They can also be dried on the ground, in which case someone moves the beans manually to rotate them and help the air circulation, this needs to be done a couple of times per hour. 

Natural coffee process

There are the natural coffee processing steps:

• Coffee cherries are picked ripe

   

• First, coffee is rinsed, but the whole fruit remains on the seed for drying
  Next, the coffee fruits are selected for drying. This is a very important part of the process, as the quality of the fruits has a huge impact on the final quality of the beans. Any molds or other defects will lower the quality of coffee. The cherries will remain on the seeds for the entire time of drying and the selection will continue throughout the drying process.

   

• After that, the cherries are drying. They are spread evenly and dried on raised beds or mesh woven mats to allow air circulation from the top as well as from the bottom. During the drying the cherries are fermenting and because the cherries are prone to mold, they are regularly rotated and sorted. The drying takes 2 – 4 weeks until the seeds inside reach the level of 11% of moisture.

   

• When the coffee is dry it’s transferred to a mill and the cherries are de-husked in a machine. There the skin, pulp, mucilage, parchment and part of the silverskin are separated from the seed in a hulling machine. The final product of this stage is green coffee.

   

• Next, green coffee is sorted by hand or by special machines and sometimes polished

   

• Finally the coffee is stored in sacks and ready for shipping

So this is an example of the dry coffee processing technique, but there are different variations of the natural method. It can be a simple or a complex process. Here is how simple it can be:

The simple natural process:

• Fresh cherry
• Drying
• He-husking in a mill
• Green coffee

What is special about the natural process?

During the natural processing sugars are fermenting and turning into alcohol. Thanks to this, natural processing can bring out more natural flavors in coffee. This process is similar to wine fermentation where bacteria, fungi and yeast play a vital role in changing the taste of the final product. It’s also worth mentioning that some natural coffee producers add yeast during the fermentation process (at the stage when about 50% of original cherry weight is lost). 

Is roasting for the dry processed coffee different?

Yes, the roasting method for dry processed coffee is normally different. The aim is to achieve a heavier bodied and sweeter roast.

What flavors in coffee does the natural process give?

Coffee processed with the natural method is rich, sweet, more fruity and has more aroma than coffee processed in other ways, it’s also heavier-bodied. 

Flavors in coffee specific to natural processing:

• Tropical fruits
• Cherry (raspberry, strawberry, blueberry)
• Berries 
• Dried fruits
• Caramel
• Cinnamon

Which coffee varieties are best for natural processing?

The yellow coffee varieties are best for natural processing. 

Where is the natural coffee processing method used?

Most robusta coffee is processed with the natural method, so it’s used in the places where robusta is grown. Also coffee in Brazil, Ecuador, Mexico, Yemen and Ethiopia can be processed with this method. 

Apart from that, the natural process is often used at the end of the season for poorer quality, commodity coffee. However, there are exceptions, e.g. in Yemen and Ethiopia the dry processing is used for high quality coffee production.

What’s the difference between washed and dry coffee processing methods?

Coffee process natural vs washed 

The dry method is technologically simpler. The difference between washed and dry methods is that in the washed process the cherry is removed from the seed and in the dry process the cherry remains on the seed for the entire drying time. Also a major difference is that the natural process takes longer. The dry method is commonly used in Robusta producing countries whereas the wet method is most often used for Arabica coffee processing. 

Above we’ve described two of the main coffee production methods. The third most popular way to process coffee is the method called honey or pulp natural.

Honey processing (pulp natural)

What is the honey coffee process?

In the honey coffee process the skin is removed from the fruit before drying but the mucilage is kept on the seed. Honey process aims to have the same quality control as the washed process and allows it to separate out the bad beans. 

Honey coffee process

Step-by-step honey processing:

• Fresh cherry
• Cherry separation
• Pulping
• Drying
• Honey parchment

The above is an example of the pulp natural process, but there are different variations of the honey method, where either more or less fruit is left for the drying. 

What type of coffee do you get from honey processing?

The type of cup you get from honey processed coffee is in between the natural and washed methods. 

Where is the honey method used?

The honey method is used most often in Costa Rica and Salvador. Generally speaking, this coffee processing method is less frequently used, but becoming more popular, especially in Central America. 

Honey method vs washed method

What’s the difference between the washed and honey coffee processing methods?

In the washed method the beans are separated from the fruit (both skin and mucilage are removed) as quickly as possible after the harvest.

In the honey processing only the skin is removed from the fruit and the seeds are dried in some or all of its mucilage. 

So now we described dry, wet and honey coffee processes. Are there more methods for processing coffee? Yes, for example one other popular way to process coffee is the semi-washed method.

Semi-washed method

What is the semi-washed method?

In the semi-washed method the skin is removed from the cherry and the coffee is dried for one day. After that, the coffee is washed and seeds are squeezed out of the fruit. Next, the beans are fermented for 24 to 48 hours. This coffee processing method gives a clean taste, more acidity, less sweetness and in general more subtle high quality coffee. 

Summary

Coffee processing methods are similar to grape processing in wine production, that’s why coffee is often compared with wine. The three main coffee processing methods include: honey, natural and washed processing. The main differences between them are about the amount of fruit removed from the seed and how much fermentation the seeds go through. This influences the flavors and quality of the coffee cup. Depending on the processing method you can get a cleaner or less clean cup of coffee, as well as more fruity and sweet flavors or more acidity in the cup.