Demystifying Coffee Processing

 8/4/2023 by Nick T from Gayo’s Best Coffee 

It seems that everyone in the coffee world is talking about Ethiopian Naturals, meaning coffees from Ethiopia that are processed naturally. But what does this mean, and what's the difference between this "natural" coffee and the other coffees we drink. Are they not natural as well? Are they processed chemically or is something non-natural added to them? Thankfully no. 

In the coffee world, there are four (4) primary ways to process coffee. This is my attempt to give a super basic summary of each process, including what it means for the farmers, and for you and me when we enjoy the coffee in our homes, cafes, and offices. Each process begins when the farmers pick the ripe fruit from the coffee tree, often called coffee cherries. Most of the time, ripe coffee cherries are red, but sometimes are orange or yellow in certain coffee varieties. If the coffee cherry is not ripe when picked, the overall taste of the coffee will negatively be affected. After picking ripe cherries, the farmers then decide how they want to process them.

Good quality coffee starts when farmer's pick ripe red coffee cherries.

A few definitions will be helpful:

Pulp - The outer skin of the coffee fruit is removed with the help of a machine (pulper)

Hull/Parchment  - The inner skin (or parchment) of the coffee fruit is removed with the help of a machine (huller)

Mucilage - The sticky remainder on the coffee bean from the fruit after the coffee cherry is pulped. 

Okay, now on with the different ways to process coffee. 

1) First, there is a process called wet hulled (sometimes referred to as semi-washed). This is primarily used on the Island of Sumatra where we source our Gayo coffee. Most other coffee producing countries don't use this process, or at least not as often. In the wet hulled process, picked coffee fruit is pulped and soaked in water overnight or possibly just left in the bag. The next day the beans are given a quick wash and then dried, followed by a trip through the huller. A little more drying and the beans are ready to sort. 

Wet-hulled coffees tend to be known for their earthy taste in the cup, but this is primarily because of poor drying techniques (on the ground or close to the road). A well processed wet hulled Sumatran coffee won't quite be on par with a fully washed Sumatran in certain ways, but the process is a lot easier for the farmers, especially in the rainy season, which means it can be processed more quickly, and consumers can get it for a cheaper price. Sweet Maria's has a good overview of a typical Sumatran on their website.

2) Washed coffees start out the same as semi-washed coffees, but after being pulped, the beans are soaked for 12 to 24 hours, with the water being changed every 6 to 12 hours depending on the art of the processor. This helps to remove the mucilage from the coffee beans. The coffee beans are then washed and dried until they contain about 12% water content. At this point the coffee is sometimes rested in the parchment which seems to help the coffee taste more consistent and stable. Resting can be anywhere from a week to three months. Next, they are placed through the huller and then dried again if needed until ready to be sorted.   

This is the main way farmers around the world process their coffee. More water is used than in the semi-wash process, and it is a bit more time intensive for the farmers. This is why the price for a Sumatran fully washed coffee will be slightly higher than that of semi-washed. The coffee is also known for having a "clean" mouthfeel, and giving a more consistent taste from harvest to harvest than natural or honey processes. 

Pulping Coffee in Action

3) Natural processed coffees are not pulped or washed after being picked. Rather, the coffee cherries are dried right away until the outer skin dries up. This can take several weeks during the rainy season. After being dried, the coffee cherries go through the huller and are dried for a few more hours before being sorted. "Wine or Winey" coffee is a naturally processed coffee that has been allowed to ferment while being dried. 

Being dried in the fruit gives the seed (coffee bean) time for natural yeast strains and bacteria to create wonderfully smelling esters. This in turn, gives each naturally process coffee a unique flavor profile. The longer the fermentation, the more complex and interesting flavors can emerge up to a certain point. Many people drinking Ethiopian naturals claim that there are flavors of strawberries and blueberries present. Sumatran naturals have a more "fruity" taste as well. While the farmers don't have to use any water for this type of process, it is the most time intensive, and the hardest to control, which results in a much higher price. For example, naturally processed coffees from Panama have been fetching extraordinarily high prices for the past several years.

4) Lastly, there is a process called pulp natural, but more commonly known as honey process. It is a hybrid way to process the coffee. Like the washed coffees, the coffee fruit is pulped right away. After this however, the coffee beans are dried in the mucilage and not washed. The mucilage has a lot of natural sugars, and the coffee will continue fermentation until the drying is done. After it is dried, the beans go through the huller to remove the parchment and are then sorted. 

Honey Processed Coffee drying in the Greenhouse

In the cup, the honey processed coffees do tend to have a paring of sugar cane sweetness and tropical fruit, like a pineapple, with a lingering aftertaste. Price-wise, the honey processed coffees lie in between the washed and naturals, and like the naturals, are less consistent than washed coffees. Personally, I really enjoy drinking the honey processed coffees, and have found that the taste can get better over time after roasted. 

There are many new processing methods that have been developed over the past few years, but these four provide the basic foundation for all coffee processing.