Process Stories Part 1: Washed


The first in a series of articles discussing coffee processes.

There's a lot that goes into making a cup of coffee. The region the coffee was grown in will effect flavor. The specific cultivar the fruit comes from will effect flavor. How the coffee is roasted will certainly effect flavor. Another crucial element in determining what you'll taste in the cup is how the coffee is 'processed.'
Maybe you've seen this term bandied about before. A barista at your local shop may have mentioned it. Maybe the words 'natural process' or 'washed' appeared on a bag of coffee you bought. Well, let's get into what we're talking about when we talk about process. 
Processing happens at wet and dry mills after the coffee cherries have been harvested. The methods used and the care put into the processing will both have dramatic effects on the characteristics of the bean from that point forward. It really is one of the most important phases in coffee’s long journey from tree to cup. Here we will discuss one of the most common processing methods used in specialty coffee and how it affects the attributes we taste in the final product.

                                                                          

Washed or “Wet” Process - This is by far the most common process used for specialty coffee. After the cherries are picked they are delivered by the farms to a “wet mill.” After the delivery is weighed the cherries are sorted for freshness either by hand or by floating them in large tanks filled with water where the ripe cherries will be more dense and sink to the bottom of the tank where they are fed into a depulping machine. This machine removes the skin and pulp (or mucilage) from the cherry leaving the seeds and parchment layer. Also remaining is a sticky mucus layer on the outside of the parchment. This is harder to remove and in order to get this last layer off, a washed coffee must go through one of two processes.  

 

Anatomy of Coffee

 

The first, and most common is for the coffee to go into fermentation tanks. These large open-topped concrete pools are filled with the recently de-pulped beans and then covered with water for somewhere between 12 to 96 hours. The exact time depends on local practices and the desired attributes of the coffee. The light fermentation that happens in these pools breaks down and loosens the last bits of fruit pulp so it can easily be removed from the parchment. This method is both water and time intensive. As a result another machine is sometimes used. Referred to in Latin America as a “lavador” or literally “washer” these machines use friction to remove the remaining gooey layer. While they tend to use less water they are also more expensive and require more energy and maintenance than the traditional, water-heavy method.

After the coffee is completely washed (though still in its parchment) it is laid out on patios or raised beds to dry in the sun. They are raked and turned frequently to avoid fermentation which would manifest down the line as a flavor defect. The weather however does not always cooperate. Occasionally, in particularly wet weather beans are kiln dried in large ovens with rotating barrels. These are not heated enough to roast the beans, just enough to dry them to the optimal internal moisture content of 11-12%.  

Once the coffee is dried it is sent to a dry mill. It's here that the hard papery parchment is removed from the bean using a machine called a “huller.” Before being shipped out the remaining beans are sorted for size, density, and color. It is then bagged and sent on its way to coffee roasters around the world.  

Washed coffees are often considered to have the most complexity and cleanness in the cup when compared to other processes. The flavor profiles and body can vary widely from origin to origin. We have a number of great washed coffees here at 802Coffee. A couple of our current favorites are the Ethiopia Girma Eshetu and the Papua New Guinea Kange Talu.

Next up: The ancient tradition of the "natural" process.