When most people think of a "coffee bean," they picture the small, brown, roasted seed that goes into their grinder. But that bean has been on quite a journey to get there — starting as the seed of a bright red (or sometimes yellow) fruit growing on a tropical shrub. Let's look at what's actually inside a coffee cherry, layer by layer.
It Starts as a Fruit
Coffee grows on flowering shrubs or small trees in the genus Coffea. The plant produces small, fragrant white flowers, and after pollination, a fruit develops over the course of several months. This fruit is called a coffee cherry — and it looks a lot like a regular cherry, though it's usually a bit more oblong.
When ripe, most coffee cherries turn bright red (though some varieties ripen to yellow or orange). Each cherry typically contains two seeds — those are the coffee beans.
The Layers of a Coffee Cherry
From the outside in, a coffee cherry has several distinct layers, each of which plays a role in the flavor of the final cup:
1. The Outer Skin (Exocarp)
The thin, tough outer skin of the cherry. It starts green and turns red (or yellow) as the fruit ripens. During processing, this skin is usually removed early.
2. The Fruit Pulp (Mesocarp)
Just under the skin is a thin layer of sweet, sticky fruit flesh. If you've ever tasted a fresh coffee cherry, the pulp is surprisingly sweet — more like a mild grape than anything you'd associate with coffee. This layer matters because in natural (dry) processing, the beans dry inside the fruit, and the sugars from the pulp influence the final flavor of the coffee.
3. The Mucilage
A sticky, gel-like layer that clings to the beans after the skin and pulp are removed. In the "honey process," some or all of this mucilage is left on the beans during drying, which adds sweetness and body to the final cup. In the traditional "washed" process, the mucilage is fermented and then washed away with water.
4. The Parchment (Endocarp)
A papery, protective hull that wraps around each individual seed. After the coffee is dried, this parchment is removed mechanically in a step called "hulling" or "milling." The parchment is sometimes used as fuel or compost at the processing station.
5. The Silverskin (Spermoderm)
A very thin, almost translucent layer that clings directly to the seed. Most of the silverskin comes off during roasting — it's what roasters call "chaff," and it floats around inside the roasting drum (or fills up the chaff collector). If you've ever noticed little papery flakes in freshly roasted coffee, that's silverskin.
6. The Seed (The "Bean")
Finally, we arrive at the coffee bean itself — actually a seed. Each cherry normally contains two seeds, sitting face-to-face with their flat sides together (which is why most coffee beans have one flat side and one rounded side). Occasionally, a cherry produces only one seed that rounds out completely — this is called a peaberry, and some people believe peaberries have a more concentrated flavor.
The raw, unroasted seed is called "green coffee." It's hard, dense, and has a grassy, almost hay-like smell. It doesn't smell or taste anything like the coffee you know — all those familiar flavors develop during roasting through a series of complex chemical reactions.
Why Does This Matter?
Understanding the structure of a coffee cherry helps explain why processing methods — how the fruit is removed from the seed — have such a dramatic effect on flavor. A washed (wet-processed) coffee, where all the fruit is removed before drying, tends to be cleaner and brighter. A natural (dry-processed) coffee, where the beans dry inside the whole fruit, tends to be fruitier and heavier in body. Honey-processed coffees, which fall somewhere in between, balance sweetness and clarity.
When we choose which coffees to roast at Olivenhain Coffee Roasters, we're thinking about all of this — the variety of the plant, where it was grown, how it was processed, and how each of those layers has shaped the seed that ends up in our roaster.