How Long Does Brewed Coffee Last? Does It Go Bad?

Sean Gregory All About Coffee
3 minute read

Have you ever had coffee from a murky pot that was a day old? In many offices and old-school diners, coffee is made in the morning and simply left to sit. Anyone who has tried it will remember the taste, and not in a good way.

Common sense implies that brewed coffee does not last forever, but when and why does it go bad? Let us investigate.

How Long Does Brewed Coffee Last?

Brewed coffee lasts just for 30 minutes or so unless stored in a sealed thermos. This is because coffee continues to oxidize long after it has been brewed.

The freshness of the beans you use will determine the freshness of the coffee brewed. This is why changing the grounds with each pot you brew is important.

Chemistry of Coffee Oxidation

Roasted coffee beans oxidize when exposed to air. This is essentially what happens to bananas when you slice them and leave them for a while.

Although oxidization is not visible to the naked eye in coffee, it substantially impacts the taste of coffee beans. This is because it causes the chemicals in coffee to degrade and be released into the air upon contact.

However, once the beans are ground, their surface area increases significantly, which can lead to the oxidation process happening a whole lot faster.

When coffee beans come into contact with water, they begin to release their acids, oils, and aromatics. This chemical reaction is also oxidation, which is responsible for the tasty cup of coffee we all know and enjoy. You just want to keep it from happening before you start brewing.

What Causes Coffee to Turn Bitter?

You should know that oxidation does not end once your coffee has been brewed. When you leave your coffee out for too long, it becomes stale due to the reaction between oxygen and hydrogen.

This is why you should never leave your coffee brewing pot alone for an extended period of time. If you can't finish it, store it in an airtight container, such as a thermos bottle.

Keep in mind that stale grounds result in stale coffee. Coffee grounds become more oxidized the older they are and the longer they sit. Even after brewing, the coffee produced from old grounds will taste stale. Coffee does not spoil in the same manner that milk does. Old coffee grounds are distinguished by an absence of scent rather than a rotten odor.

In case you are wondering, stale coffee isn't dangerous to drink; it's just unpleasant. Unless you add milk to it, in which case you should not drink it after a couple of hours.

Ready to Sip Some Hot Coffee?

If you frequently make more coffee than you can consume at once, invest in a nice thermos, which will keep your coffee fresh for a few hours. If possible, use fresh coffee beans that have been ground immediately before brewing.

You'll never have to drink stale coffee again if you follow these recommendations. Enjoy!

Now go ahead and grab some coffee from our store and have it shipped directly to your door!