Green Coffee Beans: Buying and Storing Unroasted Coffee

Green coffee is unroasted coffee: the raw, dried seed as it comes off the processing mill, still pale green or greenish-gray and largely flavorless until heat transforms it. It's how coffee is bought and sold internationally, and it's also what home roasters buy when they want to roast their own beans fresh.

What Is Green Coffee, Exactly?

Once a coffee cherry has been processed by washing, drying as whole fruit, or one of the in-between methods, the resulting raw seed is what the trade calls green coffee. By dry weight, green beans are roughly 1.0% to 2.5% caffeine and about 50% carbohydrate, and it's largely those carbohydrates, along with acids and other compounds, that roasting later transforms into coffee's familiar aroma and flavor. Green coffee itself tastes grassy and faintly vegetal rather than anything like brewed coffee, which is part of why buyers evaluate it mainly on physical characteristics and cupping samples rather than on the raw bean's own taste.

How Is Green Coffee Graded?

Two measures matter most to a quality-control lab: screen size and defect count. Screen size sorts beans by physical diameter, using sieves numbered roughly 12 to 19, where each step corresponds to about 0.4 millimeters; a screen-16 bean measures around 6.30 millimeters across, while a screen-18 bean measures about 7.10 millimeters, with larger screens generally commanding higher prices. Defect tolerances vary by exporting country and by which market a lot is destined for. El Salvador, for example, allows at most six defects per 300-gram sample under its stricter "European Preparation" grade, compared with up to twelve under its more lenient "American Preparation" standard, while Guatemala allows no more than eight defects per 300 grams for its top export grade versus as many as twenty-three under looser standards. The Specialty Coffee Association applies an even tighter bar: a 350-gram sample can't contain a single "category one" defect — the most serious kind, such as a full black or full sour bean — and still be classified as specialty grade.

How Should Green Coffee Be Stored?

Coffee typically leaves the mill at around 12% moisture, and in theory that's also the ideal moisture level for roasting, so storage is largely about holding beans as close to that figure as possible. In low-humidity conditions green coffee can lose moisture to the surrounding air, while in humid conditions it can absorb moisture it shouldn't; coffee that picks up too much moisture is prone to a "soapy" texture and fermented or moldy off-notes in the cup. Stability matters as much as the exact humidity level: swings between warm and cold, especially during shipping, can cause condensation inside containers and bags, which is a common source of damage before coffee ever reaches a roaster. Because of this, coffee is often shipped and stored in its parchment layer, or in sealed, moisture-resistant bags, for as long as possible, since that layer acts as a barrier against both moisture loss and moisture gain.

How Long Does Green Coffee Last?

Unlike roasted coffee, which stales within weeks, green coffee can hold up reasonably well for months under stable, cool, dry conditions. But it doesn't last indefinitely: coffee that sits too long, or that cycles through humid and dry conditions, gradually fades in both color and acidity, taking on a flatter, more neutral flavor that traders and roasters commonly describe as "past crop." That's one reason freshly milled, recently harvested green coffee, often marketed by its crop year, tends to be more prized than older stock, even though it's the same origin and variety.

Where Do Home Roasters Buy Green Coffee?

Home roasters generally can't buy in the container-sized volumes that commercial roasters do, so a small but well-established niche of specialty green-coffee retailers, such as Sweet Maria's, sells green coffee in home-roaster-friendly quantities, often with cupping notes and recommended roast profiles attached to each lot. Some specialty importers who primarily serve commercial roasters also offer smaller sample or retail-sized orders. Buying green and roasting at home lets a hobbyist control roast level directly and taste a coffee at its freshest, though it does mean taking on the moisture and storage considerations that mills and importers otherwise manage on a larger scale. Green coffee sold to home roasters can come from any processing method, including honey-processed or anaerobically fermented lots, and some is sold already decaffeinated for roasters who want that option without giving up control of the roast itself; see our guide to how decaf coffee is made for more on those methods.

How Does Green Coffee Compare With Jamaica Blue Mountain?

Jamaica Blue Mountain green beans are graded and shipped under the same basic principles as any other origin's green coffee: moisture control, screen size and defect counts all still apply before a bean is ever roasted. Where JBM differs is more about scarcity and reputation than about the physical bean itself — its limited, legally defined growing area means overall green-coffee supply is small relative to demand, which is part of why it's priced well above most origins regardless of how any individual lot grades out on the usual physical measures.