Commercial Storage. For a few hundred years, exporters used burlap jute sacks to ship agricultural products around the world. They’re cheap, readily available, and leave a minimal footprint. But they’re also porous. For items like unroasted green coffee, this means exposure to external moisture, light, temperature swings, and insects/pests, all of which can potentially damage the beans.
Nowadays, those same burlap sacks are lined with an ultra thick, protective polyurethane bag (usually GrainPro or Ecotact). These bags work great for trans-national shipping, and protect green coffee beans as they make their way from tropical coffee growing regions to more temperate locations around the world. These bags are also important for long term storage in domestic warehouses, like ours, where the green coffee sits until it’s shipped to roasters. How should you store it?
The answer is less complicated than it may sound. Generally, you should aim for a home storage environment that is...
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Temperate: Green coffee beans should be stored in an area that has relatively stable temperature. Ideally this means room temperature. As a general rule, cooler is better than warmer since warmer air contains more moisture (see below).
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Dry: Your green coffee should be kept in a dry place. If your beans are in a damp or wet environment, they may begin to ferment and mold, drastically altering your coffee’s flavor when roasted.
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Out of the Sun: Like virtually all natural products, light can affect quality. If your green coffee beans are in direct sunlight for too long (or on the kitchen counter by your window for example), they will begin to dry out and lose their base moisture content and flavor.
Note: Coffee is hygroscopic and absorbs air and moisture around it, which means that if you store your beans in a bag on the counter next to a bunch of bananas (for example), they’ll begin to take on that flavor as well.
These basic recommendations are probably less crucial than they may sound. Once green coffee gets to you, in an amount you plan to roast within a few months, the effects of moisture, light, pests, etc. are likely to be nominal.
We store our personal home supply of beans in the Mill47 paper bag in our garage. It’s fairly cool, dark and dry. It’s that simple. If you’re keeping your beans around for a more significant length of time or want to be more cautious, think of storing green coffee like you would flour or sugar – a mason jar, a plastic bag or an airtight canister are great choices.
At any rate, the effects of a less than perfect environment won’t ruin your precious beans as long as they’re in a cool, dry and dark place and you’re roasting them on a semi-regular basis.