This is Part 4 in a series of educational posts, designed for the consumer and/or folx building a foundation in coffee. I wrote these for work, but you get the uncensored versions here lol. Hope you enjoy! 

(Links to all posts in the series at the end)

In Botanical Basics, we learned about the coffee plant - it’s a shrub that produces berries. 

Then we discussed ripeness and picking. What happens next? Imagine a day’s harvest of ripe, red cherry - it’s beautiful, but it’s not ready for export. If it shipped like this, it would rot on the water. So how is the coffee readied for shipping?

Let’s think about the coffee seed. Each seed is covered in a thin, rice-papery layer called silverskin. Outside the silverskin is a thicker encasement called parchment. A slippery mucilage layer clings powerfully to the parchment layer. The mucilage is surrounded by pulp - the flesh of the cherry - and the whole shebang is wrapped up in thick, glossy skin. 

But the seed is the part we want. This is where processing comes in - the removal and drying of the coffee seeds. There are two main processing methods: washed and natural (and a handful of sub-methods that fall under natural). 

If you buy a bag of specialty coffee, you’ll often see the processing method on the label - this is because the method impacts flavor. Typically, one method or the other works better based on climate, access to water, and intended market. 

The washed (also called wet) process begins with the cherries feeding into a pulper -  a machine that squeezes the seeds from the fruit. 

Under pressure, the skin splits and the seeds pop out, still covered in their mucilage layer. Before entering the pulper, cherries may be submerged in water - this separates underripe cherries, which are less dense and float to the top.

  After pulping, the coffee is held in tanks for 24-48 hours to ferment. Water may or may not be added, depending on the farmer’s preference. Fermentation breaks down the sticky mucilage, but leaves the seed intact, as it’s still inside its protective parchment. After fermentation, the mucilage washes off in water. Washing doubles as another sorting measure - less dense seeds, which are underripe or otherwise defective, float to the top. 

The coffee is then spread out in a thin layer to dry over 2-3 weeks, often on raised & covered structures. It’s raked regularly to ensure even exposure to light and air. Many farms hand-sort the coffee for quality as it dries (sometimes it’s sorted right before drying, too). Typically, coffee is considered dry at 11% moisture content. 

After drying, the coffee is finally ready to be sold. It is still in parchment, which serves as a protective layer until it’s hulled away shortly before export. 

What’s different about the natural process? Essentially, the two main steps are just switched. 

In washed processing, the seeds are first removed, then dried. In natural (or dry) processing, the order is reversed - the entire cherry dries intact, raisining around the seed. Then the seed is removed from the fruit in a hulling machine. 

The natural process is difficult to do well. One primary challenge is sorting - it’s trickier to pick out defective and unripe cherries. Water, a built-in sorting mechanism in the washed process, is not used - so sorting is done by sight only. And if unripes are not caught right away, they quickly become indistinguishable from ripe, as it all dries to the same color. 

Another challenge is expedient, even drying. As the fruit dries, it ferments, and can easily start to rot. As you might imagine, the resulting coffee doesn’t taste great. If drying time runs long, due to cool or damp weather, the lot is likely compromised. Even when naturals are dried well, it’s tough to achieve consistent results. A bag of natural processed coffee might give you 6 cups of awesome coffee, and a 7th cup that’s vinegary due to an odd, fermented bean.

So why use the natural process? In many coffee-growing regions, water access is a barrier, so that can be a factor. It’s also just a simpler way of processing, operationally speaking, and is often used for commercial coffee (as opposed to specialty coffee). 

Although naturals can be divisive - some people love to hate them - they hold a special place in specialty coffee. 

While washed coffees are heralded for their clean profile and bright acidity, naturals are often more wild and fruity, imbued with interesting flavor character as the berry dries around the seed. Most specialty coffee is washed, but coffee companies usually carry a few naturals as well. 

If you’re interested in trying a washed vs. a naturally processed coffee, check the label - now you know why the processing method is listed on coffee bags. As always, thank you for reading, and I hope this was helpful!

If you’re interested in learning more, check out the other posts in this series:

Part 1: Fuck You, Pay Me

Part 2: Botanical Basics

Part 3: Ripeness & Picking

Questions? DM me! I'm on Instagram: @umeshiso_