Can You Drink Coffee That Was Left Out Overnight?

If you are a student that lives in a college dorm, chances are that you’ve left stuff out for the night and ate or drank it in the morning. At the time, you might not think that there’s anything wrong with it, but if you are wondering whether you can drink coffee that was left out overnight or not, don’t worry because we’ve got you covered. 

While you can drink coffee that was left out overnight, it is not recommended as the taste fades away. Leaving it out overnight does not give it any toxic attributes whatsoever. However, coffee mixed with milk can accumulate mold.

If you want to know exactly what happens to coffee if it is left out overnight, worry not because we will show you that in the next section below!

The Taste Deteriorates 

When you leave the coffee out overnight, it will go through a process known as oxidation. This will cause the coffee to go stale and the taste will be extremely bitter and it will deteriorate. That is why people say that coffee is best when it is fresh.

On top of that flavor, the aroma of the coffee will also deteriorate, giving it a bitter scent. Keeping coffee inside a refrigerator is optimal as it will allow it to keep its aroma and taste longer. 

It Can Accumulate Mold

Brewed coffee has a tendency to go rancid and accumulate mold if you do not refrigerate it. This is especially true if milk is mixed with coffee. It is suggested that you consume the coffee within two hours of mixing milk in it. Otherwise, chances are that it will go bad. 

If you want to save the coffee for later, you can always put it in a fridge to keep it cool but even then, it is not recommended to let it stay there for more than a day maximum. 

The Oils Go Bad

While coffee will start to go bad and have a bitter taste only after two hours of being out of the fridge, the coffee oils will go rancid if you leave them out for more than four hours. Again, this is due to the aforementioned oxidation process. 

To make the coffee last longer, we suggest that you put it in an airtight thermos to keep it warm and avoid the oxidation process. Either this or if you are at home, you can always put it in a refrigerator. 

While this is an extreme example, check out this fascinating video of what happens if you leave your coffee out for a whole month:


While it isn’t necessarily bad if you drink coffee that was left out overnight, we do not suggest it. The coffee will have a bitter taste, it will smell bad, and the oils will go rancid. If you mix milk with the coffee, it might even accumulate mold if you leave it out. Now that you know this, make sure that you share this knowledge with your family and friends that love to drink coffee.

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