A follow-up question from last week discussion of Giling Basah or wet-hulling: how are ‘natural coffees’ processed?

To borrow from that previous email, the central goal in processing is to take the coffee cherry and remove its many layers: skin (exocarp), the mucilage (mesocarp), and the parchment (endocarp) to prepare it for roasting.

It is the initial stage in that chain that differentiates natural processing. For a fully-washed coffee, mills or farms pulp the peel in order to prepare the bean for fermentation and consequential removal of mucilage. With a natural coffee, the outer layers are left intact to dry passively on beds. Once a specific moisture level is met, the whole hull is mechanically removed and the bean is ready for export.
Naturals are divisive because they retain flavour characteristics (related to yeasts and bacteria) from those outer layers. Many love these rich fermented notes. I have a real soft spot for natural Ethiopian coffees with spicy – yet creamy – strawberry and blackberry. However for some, the way naturals tend to universally present similar tastes make them less interesting than fully-washed coffees. There are also some real opponents to these cup profiles. I have heard naturals compared to cheap port wine, dirt, expired jam, and even … diapers.

To wade into this debate, I would cite my ongoing argument that we should fight against universalizing coffee. I love experiencing the individual attributes of origin, so I generally prefer washed coffees. However, I absolutely realize that naturals can be extremely interesting and should not be discounted or ignored based on broad assumptions. In fact, stay turned for a natural on our offer sheet later this summer.

tl;dr: natural processed coffees dry passively within the outer layers of the cherry.