How to store coffee beans

What makes coffee go stale

Roasted coffee does not spoil the way milk does. It fades. The aromas that make a good cup are volatile compounds, and they slowly escape or break down after roasting. Four things speed that up:

• Air. Oxygen reacts with the oils and aroma compounds in the bean. This is the biggest factor, and it is why a sealed container matters more than anything else.
• Moisture. Roasted coffee is dry and absorbs water and smells from the air around it.
• Heat. Warmth speeds up every chemical reaction, including the ones that flatten flavor.
• Light. Direct sunlight warms the beans and breaks down compounds on its own.

Good storage is simply keeping those four away from your coffee for as long as it takes you to drink it.

The best way to store coffee at home

Use an airtight, opaque container

A canister with a gasket seal, ceramic or stainless steel, does the job well. Clear glass jars look great on a counter, but they let light in, so keep them inside a cupboard. Choose a container close to the size of what you are storing. A half empty canister holds a lot of air.

Or keep it in a good bag

Many roasters pack coffee in bags with a one-way degassing valve, the small round vent on the front. Freshly roasted coffee releases carbon dioxide for days after roasting. The valve lets that gas out without letting outside air in. A valve bag that you squeeze the air out of, roll down tight, and clip shut is a perfectly good everyday container. Paper bags with no liner and no seal are not; move that coffee into something airtight.

Pick a cool, dark spot

A cupboard away from the oven, dishwasher and toaster is ideal. Above the coffee maker is a common spot and a poor one, because it gets warm and steamy every morning. In a New Jersey summer, a kitchen counter in the afternoon sun can get surprisingly warm, so a closed cabinet is worth the extra step.

Whole bean keeps longer than ground

Grinding multiplies the surface area of the coffee many times over, which exposes far more of it to air. Ground coffee loses aroma noticeably faster than whole bean, often within days rather than weeks once the bag is open.

If you have a grinder, buy whole bean and grind just before brewing. If you buy ground coffee, buy smaller amounts more often, keep the bag tightly sealed, and aim to finish it within a couple of weeks of opening. Either way, the storage rules are the same; ground coffee just has less margin for error.

Signs your storage is not working

If a bag tastes great for the first few days and then goes flat well before it is finished, look at where it lives. A loose clip, a canister that is mostly air, or a shelf above the kettle can all shave weeks off a bag. Fix the container first; it is the cheapest upgrade in coffee.

Why the fridge is a bad idea

The fridge feels like the place for anything you want to keep fresh, but it works against coffee in three ways.

• Condensation. Every time you take a cold container into a warm kitchen, moisture condenses on the beans.
• Odors. Coffee absorbs smells. Leftover onions, garlic and takeout will find their way into your cup.
• It is not cold enough to help. A fridge is cool but humid, and it does not slow staling enough to make up for the moisture and odor problems.

A dark cupboard at room temperature is better for coffee you are drinking now.

How to freeze coffee beans the right way

Freezing is useful when you have more coffee than you can drink in a few weeks, for example a gift bag or a bulk purchase. Done properly, it slows staling a great deal. Done carelessly, it does more harm than good. Follow these rules:

1. Freeze it early. Freeze coffee you will not open soon, not the last third of a bag that has been open for two weeks.
2. Portion it first. Divide the beans into airtight bags or jars that each hold about a week's worth, or a single brew's worth if you want to be precise.
3. Seal it well. Squeeze out as much air as you can, or use a vacuum sealer. Freezer burn and odors are the same air and moisture problem at a lower temperature.
4. Thaw it sealed. Take out one portion and let it come to room temperature before you open it, so condensation forms on the outside of the bag and not on the beans.
5. Never refreeze. Once a portion has thawed, keep it in the cupboard and use it up. Repeated freezing and thawing is where most of the damage comes from.

Quick storage reference

One more habit helps more than any container: buy about as much as you drink in a few weeks. If you are not sure what that is, our guide to how much coffee you need per month turns cups into pounds.