The Process of Processing: A Primer on Coffee Processing
“What kind of detergent do they use in the fully washed process?”
This was one of responses from some of my favorite—and snarky—baristas when we were discussing washed coffee. Obviously, they were kidding, but if you’ve never spent time at a coffee mill, which the majority of us coffee drinkers haven’t, then the world of coffee processing can be vague and somewhat magical: something that resembles a cherry goes in the mill and bags of green coffee come out the other side! Maybe you’ve just been introduced to specialty coffee or perhaps you’ve been drinking that 90 point Ethiopian for years. Either way, I hope to shed some light on wet processed coffee—specifically fully washed coffee.
Even though we only see the final product, coffee begins its journey far from where you’re drinking it! Coffee is grown in seventy countries across the globe and has to be harvested, processed, packed, shipped, roasted, ground, and brewed before it brightens your morning. So let’s talk about that “processed step” and why it matters.
The coffee bean you see is actually the seed of the coffee fruit, which is known as the coffee cherry. How the coffee bean is separated from the rest of the cherry and what happens after that is what we call processing.
Processing happens in two ways, dry (natural) and wet. Dry processed coffee is harvested and then dried with the coffee bean still in the coffee fruit. Once the fruit is dry, the coffee is milled (which seperates the fruit from the seed) and bagged up to be shipped off.
But wet processing removes the seed (i.e. the coffee bean) from the fruit, which is known as pulping. After the coffee has been pulped, a thin slimy layer is still covering the coffee bean. This layer is called mucilage, and how it is dealt with determines which of the three wet processing paths the coffee takes. The coffee can be fermented, which yields fully-washed coffee, the mucilage can be removed with a machine, which yields semi-washed coffee, or the coffee can be dried with the mucilage left on it, which yields pulped natural coffee.
So to understand how coffee is processed you have to ask yourself, “is the coffee pulped?” No? Then the coffee has been dry processed. Yes? Then the coffee has been wet processed and then you have to ask, “What happened to that slimy stuff, mucilage?” If it was removed through fermentation, then it’s fully-washed coffee. If through mechanical demucilager, then it’s semi-washed coffee and finally, if it wasn’t removed at all, it’s pulped natural coffee.
Well that’s all good and swell, but why does processing matter? Two words—flavor profile. Each processing method can bring out different flavors and tastes in the coffee. In fact, if you process the same coffee three different ways you’ll get three different flavor profiles! That’s pretty cool, but let’s talk about fully washed coffees because these are incredibly popular—and for good reason. If you look around the internet, the majority of high scoring and exceptional coffees are fully washed coffees.
Fully washed (also known as “washed”) coffees are distinguished by their clean and crisp flavor profile. Basically, is there a flavor that comes across clear as day when you’re sipping a cup of coffee? Sometimes you could be sipping a cup and not quite able to put your finger on the flavor your tasting. Other times though, you take a sip and bam! Blueberries all day long. More than likely, that coffee is a washed coffee. This purity of flavor is the result of fermentation during the processing. After being pulped, the coffee sits in a tank of water for 24-48 hours and the mucilage layer dissolves. Fermentation is very complex, but it is the key to washed coffees and what distinguishes them from other coffees.
So to wrap it up, there are two major categories of coffee processing: dry and wet. Wet processing can be broken down into fully washed, semi-washed, and pulped natural. What makes fully washed unique is the fermentation step, which produces that kick-in-the-mouth clean flavor. Now go and impress all your coffee loving friends with your new knowledge!