What is the difference between: Natural, Honey and Washed Coffee Processing?

A coffee cherry has, roughly speaking, five layers

The five layers are:

1. Skin / Pulp: On the outside, the two coffee seeds are covered by a cherry-like skin. With the exception of dried-in-the-fruit or Natural Process coffee, this outer layer is removed within a few hours of harvest. In an edible cherry (like a nice plumb and sweet Rainier cherry from Eastern Washington), we might call this skin the “flesh”. In coffee, the skin is mostly considered a by-product (some make tea out of it).That’s why it’s called “pulp” and the machine to remove it is called a depulper.

2. Mucilage: Beyond the skin lies the mucilage, a sticky, gluey substance surrounding each of the two seeds. Since it is so sticky and sugary, it is sometimes called Honey. (Mucilage is found in most fruit. It’s not unique to coffee: http://en.wikipedia.org/wiki/Mucilage)

3. Parchment: After the mucilage, a layer of cellulose protects each of the coffee seeds. When dried, this layer looks and feels like parchment paper, hence the name.

4. Silver skin / Chaff: Further inside, an even thinner layer coats the seed. This layer is called the silver skin because of its somewhat silverish sheen. This layer comes off during roasting. If you ever notice flakes in ground coffee, that is usually bits of silver skin or chaff that didn’t separate from the beans during the roast process.

5. Seed / Coffee Bean: As you’ve already discovered, basically the coffee bean is one of the two seeds from inside the coffee cherry (Peaberries are an anomaly in which only one small, round seed formed inside the cherry. Usually, about five percent of all coffee is graded as a peaberry.) It is dried and infertile by time we receive it, ready to roast.

The Three Principal Processing Methods in Coffee We know of three principal categories of processing methods. These three processes differ in the number of layers that are removed before drying. Here is the short list:

1. Natural or Dried in the Fruit Process – no layers are removed.

2. Honey Process – skin and pulp are removed, but some or all of the mucilage (Honey) remains.

3. Washed Process – skin, pulp, and mucilage are removed using water and fermentation. Also called Fully Washed. This is the conventional form of Arabica coffee processing used in most parts of the world. It is possible to skip the fermentation step by using a high-tech pressure washing machine to remove the skin, pulp and some or all of the mucilage. This process is called Pulped Natural.

In terms of how many layers of the fruit are removed, and how much water is used, the Honey Process is about mid-way between the Natural (Dry) and Washed (Wet) Processes.