Green coffee beans: what raw, unroasted coffee is and how to use it

This lesson explains what green coffee beans are, how farms prepare them, what roasting does to them, how to store them if you roast at home, and what the research says about green coffee extract. It sits between our lessons on origin, processing and roast and the roasted coffees in our catalog.

What are green coffee beans?

Green coffee beans are raw, unroasted coffee: the dried seeds of the coffee cherry after the fruit and husk are removed. They are pale green to yellowish, dense and hard, and they do not yet taste like coffee. Roasters buy them, roast them and sell them as the brown beans you know.

A coffee cherry usually holds two seeds. After harvest, the farm or mill removes the fruit, dries the seeds and strips off the papery parchment layer. What is left is green coffee. It is shipped in bags from producing countries to importers and roasters, who roast it close to when it will be sold.

"Green coffee," "raw coffee beans" and "unroasted coffee beans" all mean the same thing. Green coffee is far more stable than roasted coffee, which is why the industry ships it green and roasts it near the customer. It is also where a lot of a coffee's character is set. Origin, variety, processing and even decaffeination all happen before roasting.

Green coffee is graded before it is sold. The Specialty Coffee Association grades a 350 g sample for defects, and specialty-grade coffee may have zero category one defects. The SCA also calls for water activity below 0.70, a measure of how free the moisture in the bean is to cause trouble.

How are green coffee beans processed before roasting?

Processing is how the farm removes the cherry fruit and dries the seed, and it shapes flavor before roasting starts. The main methods are washed, natural, honey and newer experimental methods such as anaerobic fermentation. Each leaves the green bean with a different flavor potential that the roaster then develops.

Catalog details are roaster-reported. Flavor directions are general tendencies, and individual coffees vary.

Experimental methods are growing fast. In our own catalog of 124 coffees, about 1 in 5 that publish a process use an experimental method, and Colombia and Ethiopia appear in 41% of coffees. See coffee by the numbers for the full breakdown.

Decaffeination also happens at the green stage. The beans are soaked or steamed so caffeine can be drawn out, then dried and roasted like any other coffee. The Peace Coffee Decaf French Roast is a water-process decaf made this way from Honduran green coffee.

What happens to green coffee beans during roasting?

Roasting heats green coffee until it dries, browns and cracks, which builds the aroma and flavor we call coffee. The bean loses water, about 10% to 16% of its weight, and swells in size. Audible "first crack" begins around 395 to 405°F (202 to 207°C), and darker roasts go further.

Early in the roast the beans dry out and turn from green to yellow. Then browning reactions take over, including the Maillard reaction, and sugars caramelize. At first crack, built-up steam and gas pop the beans open, much like popcorn. Many light roasts finish soon after. If the roast continues, a quieter second crack arrives and oils start to show on the surface.

Approximate home-roaster averages from Sweet Maria's (2021, 2023). Temperatures vary by roaster and probe placement.

Roasting also changes the chemistry in the cup. Green coffee is rich in chlorogenic acids, and roasting breaks them down. A 2013 study in Food Chemistry of 18 commercial coffees found 27 to 121 mg of chlorogenic acids per 200 ml cup, and the authors reported that heavy roasting had a detrimental effect on that content.

Can you roast green coffee beans at home?

Yes. Home roasting is a real hobby, and green coffee is sold by specialty suppliers in small bags. You can roast in a dedicated home roaster, an air popcorn popper or a heavy pan. Expect smoke and flying chaff, and plan on a few batches before the results taste the way you want.

A simple first roast looks like this:

1. Buy a pound or two of green coffee from a supplier that lists origin, process and crop year.
2. Roast outside or under a strong vent hood. Chaff, the papery skin, flies off and smoke builds quickly.
3. Keep the beans moving and listen for first crack. Stopping shortly after first crack ends gives a light roast. Going toward second crack gives a darker roast.
4. Cool the beans fast, for example by tossing them between two metal colanders.
5. Weigh before and after. Sweet Maria's uses weight loss as a roast-level guide, with roughly 12% to 13% for a light City roast and around 15% for very dark roasts.
6. Store the roasted coffee loosely covered at first, since it releases carbon dioxide, then move it to an airtight container.

If you would rather drink than roast, every coffee on our explore coffees page arrives already roasted by an independent roaster.

How do you store green coffee beans, and how long do they last?

Store green coffee somewhere cool, dry and dark, sealed away from strong smells, and it can hold its quality for months. Green coffee is dried to about 11% to 12% moisture and absorbs water and odors easily. Hot or humid rooms can make it fade within a few weeks.

Good storage habits for home roasters:

• Use a sealed container. A glass mason jar is a fine start for small amounts, and hermetic, multi-layer bags work for larger ones. Paper bags are a poor choice for long storage.
• Keep it off the floor and away from the stove, sunny windows and dishwashers.
• Keep it away from spices, cleaning products and anything else with a strong smell.
• Label each bag with the purchase date and crop year, and roast older coffee first.

Signs that green coffee has aged are mostly noticed after roasting: flat, papery or woody flavors and less sweetness. Mold is the real safety problem, and it comes from moisture, so any beans that smell musty or show fuzzy spots should be thrown out.

Is green coffee bean extract good for weight loss?

The evidence is weak. The best-known study behind green coffee extract weight-loss claims, published in 2012, was retracted by its authors in 2014. That same year, the Federal Trade Commission reached a $3.5 million settlement with the company behind it over charges that the study was too flawed to support any conclusions.

Green coffee extract is a concentrate made from unroasted beans, usually sold for its chlorogenic acids. The 2012 paper, by researchers at the University of Scranton, was heavily promoted on television. According to Retraction Watch, the FTC alleged that the sponsor, Applied Food Sciences, relied on a study so flawed that no reliable conclusions could be drawn from it.

Green coffee extracts can also contain caffeine. If you are thinking about a green coffee supplement for a health reason, talk it over with your doctor first, especially if you take other medications.

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