What is green coffee? Unroasted beans explained

How does a coffee cherry become green coffee?

Through processing, drying and hulling. After harvest, the farm removes the fruit, either before drying (washed) or after it (natural), or leaves some of it on (honey).

Drying brings the beans down to a stable moisture level. Wikipedia says washed coffee leaves the mill at about 53% moisture and must be dried to 10 to 12% before it is stable.

Hulling then strips the last layers. Wikipedia describes it removing the parchment of washed coffee, or the whole dried fruit of a natural. Perfect Daily Grind notes some coffee is sold with the parchment still on, as "parchment coffee."

What is in a green coffee bean?

Mostly carbohydrates, with protein, oils and caffeine. Wikipedia's coffee bean article gives these figures for dry green coffee:

Green coffee is also rich in chlorogenic acids. Wikipedia says more than 70% of them are destroyed during roasting. Green coffee extract, sold as a supplement since the mid-2000s, is marketed on that content.

How is green coffee graded?

Roasters grade it by looking for defects, checking moisture and sorting by size. The Specialty Coffee Association publishes the grading protocol.

Cropster summarizes the SCA method.

A grader inspects a 350 gram sample. To qualify as specialty, it should have no Category 1 defects and no more than five Category 2 defects. That is separate from the cupping score that also defines specialty coffee.

Size is measured with screens. Wikipedia says the holes are measured in sixty-fourths of an inch, and most green coffee falls between screens 12 and 19.

How long does green coffee keep?

Much longer than roasted coffee, though not forever. Perfect Daily Grind says roasters aim to keep lots for no longer than about a year.

Moisture is the main thing to control. Perfect Daily Grind says the ICO recommends 11%, with 10 to 12% widely accepted. Below 10% risks a loss of cup quality, and too much humidity raises the risk of mold.

Cropster gives the same 10 to 12% range under SCA standards. Wikipedia adds that the International Trade Centre recommends 11% moisture and cool storage.

Is decaf made from green coffee?

Yes. Caffeine is removed while the beans are still green, before roasting. The National Coffee Association says the process removes around 97% of the caffeine.

Decaffeination leaves its mark on the green bean. Perfect Daily Grind says Swiss Water decaf comes out a few shades darker than regular green coffee. It is also lighter and less dense, which changes how it roasts.

The decaf page covers the methods and how to brew it.

Does green coffee matter when buying a grinder?

Not directly, since you grind roasted coffee, not green. But roasting transforms the bean, and what it starts as still shows up at your grinder.

Wikipedia's roasting article says beans lose 15 to 18% of their mass and roughly double in volume. Around first crack, the hard green seed turns brittle and brown.

Counter Culture says denser, higher-elevation coffees need a finer grind. Its grind guide also notes darker roasts are less dense and need a coarser setting.

That is one reason two coffees can need different settings on the same grinder. The grind converter gives a starting point, and taste does the rest.