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How Long Does Coffee Last?
This article has been written by experts and fact-checked by experts, including licensed nutritionists, dietitians or medical professionals. The information in the article is based on scientific studies and research.
It is designed to be honest, unbiased and objective, and opinions from both sides of an argument are presented wherever there is disagreement.
The scientific references in this article (marked by 1, 2, 3, etc.) are clickable links to peer-reviewed research material on the subject being discussed.
How many times have you walked into a kitchen or an office break room, asked “Is the coffee fresh?” – and no matter what the answer was, poured yourself a cup anyway?
The moral of that story: when coffee drinkers need coffee, they drink coffee.
If coffee is absolutely rancid, sure, you’ll throw it out. But even though most busy people would vastly prefer a fresh, delicious cup of coffee, it usually has to be pretty bad before they’ll actually go to the effort of brewing a fresh pot.
The obvious exceptions, of course, are people with a lot of time on their hands – or coffee lovers who want nothing but the finest brew. Everyone else who has stuff to get done will often make do with whatever excuse for coffee happens to be available.
Here’s the good news: even a really bad cup of coffee won’t get you sick.
Here’s the better news: it’s not really difficult to ensure that you always have the freshest cup of coffee when you’re waking up in the morning, or when you’re desperate for a pick-me-up later in the day.
Let’s take a deeper dive on the subject and actually cover two issues: the coffee that’s been sitting in the coffeepot, and the ground coffee or coffee beans that have been sitting in your pantry.
How Long Does Coffee Last After Brewing?
Fresh coffee usually stays aromatic and delicious for an hour or two. After that, it begins to take on the stale taste and aroma that remind you of break rooms and greasy spoons.
There are several reasons why that happens, but the primary culprit is oxygen.
It’s easier to understand the process by first thinking about vegetables and fruit. When oxygen in the air contacts the flesh of a potato or an apple after they’ve been peeled, it alters the foods’ molecular structures and turns the potato or apple brown through the chemical reaction known as oxidation. It’s basically the same reaction that makes iron rust over time.
When coffee beans are roasted, they become relatively unstable in chemical terms. So when oxygen comes in contact with the lipids and proteins in coffee, oxidation and the resulting chemical changes occur rapidly, and exposure to hot water accelerates the process even more. Since coffee is already brown, the oxidation process won’t change its color and the coffee won’t “look” like it’s gone bad. Oxidation simply causes the coffee to take on that stale, bitter taste we’re all familiar with.
Something else happens after coffee sits in a pot or cup, too. Some of the brew’s characteristic flavor chemicals evaporate, leaving weaker coffee that doesn’t taste “right.”
So does coffee go bad after sitting for a while? Well, it’s not undrinkable, or even worse, moldy and mildewy. It will just be bad, as in “Yuck! How long has this been sitting here!”
Those who have made cold brew coffee are a bit more fortunate. Cold brew concentrate will be fine in the fridge for a week or so, as long it hasn’t been diluted. After that, it will quickly lose its flavor. On the other hand, if you brew espresso it has to be drunk almost immediately. After a few minutes, the crema recedes into the coffee and you’re left with what baristas call a “dead espresso.”
How to Make Sure Your Coffee Is Fresh
Your coffee will be freshest if you grind the beans yourself. If you do, there are several ways to prevent the coffee from quickly going stale.
The first is to drink it as soon as the brewing process is complete. If you’ve made more than a cup, drink it within an hour or so. Reheating coffee can make it hot again, but once the chemical changes have occurred you can’t make it taste good again. If you need to keep your coffee warm, an airtight thermos will do a decent job for a few hours. Made too much? It’ll stay reasonably drinkable for a few days as long as you put it in the refrigerator – just don’t expect it to taste as good as it will right after you brew it.
The other important steps are to grind your whole beans just before you’re ready to make the coffee, and only grind the amount that you’ll use right away. Why? Again, to avoid oxidation. Before coffee has been ground, oxygen can only contact the outside of each bean. After grinding, oxygen starts degrading every bit of the coffee grounds, which can begin to go stale even before they’re in your coffee maker.
What if you have too many beans to grind right away, don’t have a coffee grinder, or simply prefer the convenience of ground coffee? Read on.
How Long Can Coffee Be Stored in Your Kitchen?
Obviously, no one is going to run out to the grocery store to buy just enough beans – or ground coffee – to make a single cup or pot. That means we have to talk about the shelf life of coffee.
Let’s start with how long coffee beans last. They’re at their freshest for seven to ten days after they come out of the roasters, which is why reputable coffee producers print a “roasted on” date on their packages. That date helps you purchase the freshest beans possible. (Ignore the “expiration date” you may see on some packages, since it’s relatively meaningless. There’s no such thing as “expired” coffee, just old coffee that’s gone stale.)
Why do beans begin to lose freshness after a week or so? Once again, as Ron Burgundy would say, it’s science.
As coffee beans are roasted, they begin to release carbon dioxide in a process known as degassing. They’re still releasing CO2 after they’re packaged, which is why you’ll see a small vent hole in most of the packages sold by quality coffee roasters. The hole is actually a one-way valve that lets carbon dioxide out, but prevents oxygen and moisture from getting in. In about a week, once the degassing has finished, oxidation will begin.
The valve delays oxidation, but it can’t completely stop it from occurring. That’s the reason that coffee beans are best used within a week or two of their roasting date, and why it’s always a good idea to only purchase the amount of beans you will be using that month.
(Vacuum-sealed coffee packaging is not as desirable and should be avoided if possible. Carbon dioxide released by the beans is forced to stay in the vacuum-sealed bag, where it can damage the beans’ flavor or even cause the bag to explode.)
Ground coffee oxidates more quickly than whole beans, because it has a much larger surface area exposed to the air. Naturally, that means ground coffee should be used even more promptly than beans. About two weeks after you’ve opened a package of ground coffee, it will no longer be fresh.
The news isn’t all bad, though. It won’t be quite as good as it was right after roasting, but whole bean coffee can last about six months when stored properly. If you vacuum-seal and freeze it, it can last for a couple of years – although it definitely won’t taste as good when you thaw it out, grind it and brew it.
Ground coffee’s unopened shelf life, as you’d probably expect, is shorter. Figure 3-4 months before you’ll have to throw it away or repurpose it. And it can last at least a year if you put it, vacuum-sealed and unopened, into the freezer. (Again, caveat emptor on the freezer thing.) Pods like Keurig K-Cups can last a few months longer. Prefer decaf coffee? The time frames are about the same.
Those who use instant coffee often keep a jar in their refrigerator until they use it up or until the world ends, whichever comes first. That’s not the best idea. No matter what expiration date they print on the jar or bottle, instant coffee will start to go bad within two weeks of opening the container. If you leave it sealed, you should have a year or two before it goes bad.
The Best Ways to Keep Coffee Fresh
You can’t keep coffee fresh indefinitely, but you can stave off the inevitable oxidation that will render it stale and bitter.
The key consideration is where you keep your coffee. First of all, never keep beans or ground coffee in their store packaging, and don’t put them in a random canister that you keep on the counter. Always store coffee in an opaque, airtight container, in order to keep out as much oxygen and light as possible. That limits oxidation and “photodegradation,” the process by which atmospheric elements change the chemical makeup of the coffee. Containers made of ceramic, glass or stainless steel are best.
Keep the container tucked away from the elements; a closed cabinet or pantry is best, as long as it doesn’t get too hot or cold. Coffee should be stored in a dry place and at room temperature, because heat, drastic changes in temperature, and humidity can cause condensation to form and the oxidation process to speed up. That also means that a cabinet right over the stove should be off-limits, no matter how close it is to your coffee maker.
What’s the best way to regularly enjoy fresh coffee? Aficionados often shell out extra money to have small quantities of beans regularly delivered to their home. It’s a pricey solution – but it ensures that they always have the freshest coffee on hand.