How Long Do Coffee Beans Last?
You have probably seen someone do it at the supermarket, or done it yourself: reaching past the front row of bags and digging to the back of the shelf for the most recent roast date.
Specialty coffee taught all of us to read that date as a sign of quality. It does matter. But we may have given it a little too much weight, because the freshest bag is not always the best cup.
Here is how the timeline really works.
The timeline
| When | What is happening |
|---|---|
| Day of roasting | The beans are full of carbon dioxide and taste sharp and uneven |
| 2 to 3 weeks after roasting | The gas has settled. This is when most coffee tastes its best |
| Up to about 4 months, sealed | Still good in an unopened bag with a one-way valve |
| After opening | It fades over a few weeks |
Three things follow from that.
Coffee needs a rest. Roasting produces carbon dioxide, which keeps escaping for days. Brew too soon and the gas gets in the way of the water, so the cup tastes thin or sharp. Light roasts often need the full three weeks.
A sealed bag buys you months. The valve on a coffee bag lets gas out without letting air in. Unopened, a bag stays good for about four months.
Opening the bag starts the clock. Air does the damage. Once the bag is open, the coffee slowly loses its aroma and starts to taste flat.
Roast date and best-by date
There are two kinds of date on coffee, and they tell you different things.
- A roast date tells you when the coffee was roasted. This is the useful one. Most specialty roasters print it.
- A best-by date tells you when the roaster thinks the coffee will be past its best. It is often a year or more after roasting, so it says little about how fresh the bag is today.
If a bag has only a best-by date, you cannot tell how old it is. If it has a roast date, aim to open it between two weeks and four months after that date.
Whole bean or ground?
Whole beans keep far longer than ground coffee.
Grinding breaks each bean into hundreds of pieces and exposes all of it to air at once. Ground coffee starts losing aroma within minutes and tastes noticeably flatter within days.
If you can, buy whole beans and grind just before you brew. It is the single biggest improvement most people can make at home.
How to store it
- Keep it in its bag. Most coffee bags are made for the job. Squeeze the air out, roll the top down and clip it.
- Or use an airtight container that keeps out light.
- Cool, dark and dry. A cupboard away from the oven is right.
- Not the fridge. It is damp, and coffee picks up moisture and smells.
- The freezer works, done properly. Freeze the coffee airtight, in portions, and take out only what you need. Do not move one bag in and out.
How to tell if coffee is past its best
Smell it. Fresh coffee smells strongly of something: fruit, chocolate, toast. Stale coffee smells faint and papery.
Then taste it. Stale coffee is not harsh. It is dull. The flavors that made it interesting are simply gone.
Buy at the pace you drink
The simplest way to always have fresh coffee is to buy only what you will finish in two to three weeks. A 12 oz bag makes about 22 cups, so one bag suits one person drinking a cup a day.
