Can You Reheat Coffee? Why You Shouldn’t & What You Can Do

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coffee mug in microwave oven

You brewed a fresh pot of coffee earlier this morning.

A couple of hours later, it’s still good, but stone cold.

So, can you reheat coffee?

Sure, technically, you could.

Should you reheat it?

Definitely not. 

See, reheating your coffee will make it taste completely different. And not in a good way. 

It might be warm again, but it’ll be a far cry from the cuppa you knocked back when it was freshly brewed.

There’s one notable exception to this rule, and we’ll talk about that a little further down as well.

Ready to find out more?

Let’s dive straight into it!

Why Does Reheating Coffee Make It Taste So Bad?

woman drinking bad coffee making grimace

If you’ve ever tried reheating coffee, you’ve probably noticed that it tastes pretty terrible.

Heating coffee makes it turn bitter, and it loses any flavors and aromas that it once had.

So, why is that?

Well, you see, from the bean to your cup, coffee goes through various processes that involve heat. Every time it goes through any of these processes, the compounds inside it change, and it becomes more bitter as a result.

If a coffee bean is roasted and brewed at the right temperature for the right amount of time, it won’t be bitter. It’ll still have some bitterness to it, but it’ll also have other flavors, acidity, and sweetness that will balance it out.

But if you take that perfectly roasted and brewed coffee and stick it in the microwave oven, or put it on the stovetop to heat it up again, what will you end up with? 

You guessed it – a bitter mess.

So, if your coffee does go cold but it’s still good, stick a few ice cubes in it and enjoy a nice iced coffee. 

If you really want it hot, brew a fresh pot. It’s always a better option than trying to reheat it, no matter which method you’re using.

If you want to warm up your coffee in an oven, be sure that the mug is oven-safe. You can check the label underneath the mug or on the packaging to be sure.

What About Coffee Pots That Keep Your Coffee Warm?

coffee pots with hot plates

Same thing here.

I’d never recommend using any type of coffee maker that keeps your coffee warm all day long by keeping it on low heat. These coffee makers all make terribly bitter, over-extracted coffee. 

This is because they continue to extract the coffee for hours on end, essentially burning it in the process.

You know that terrible coffee that you get at old school diners? 

Well, sitting on a hot plate all day is the secret ingredient to making it taste so repulsive.

Is Reheating Coffee Bad For Your Health?

Well, no.

Maybe for your spiritual health. If you’re a coffee lover, the taste of bitter, burnt coffee can be enough to crush your soul. 

But as far as your physical health goes, there’s technically nothing wrong with drinking reheated coffee. The worst that could happen is burning your tongue if you heat it up too much.

There’s an old rumor going around that reheating coffee causes cancer. The origin of this information is known, but in any case, it simply isn’t true. While coffee’s cancer fighting properties might be diminished by reheating it, it certainly won’t cause cancer either.

What Can You Do Instead Of Reheating Your Coffee?

woman holding coffee thermos

Most of us only use our thermos cups when we’re making coffee to go.

But have you ever thought of using one at home?

Believe it or not, this is actually the best way to keep your coffee warm for longer. 

That isn’t all you can do, though.

It also helps to warm up the pot you’re making your coffee in before you start to brew it. You can do this by swishing some hot water around in there and emptying it out before you get started. 

Doing the same thing with your thermos or coffee mug is also a good idea.

That way, your coffee won’t go cold as quickly, and you’ll be able to enjoy it for longer – without the need to reheat it.

Heating Cold Brew Coffee

So, what about cold brew coffee?

While it’s most commonly enjoyed cold, this is the one type of coffee you can actually heat up without ruining it. 

There are 2 different ways you can do it:

  1. Making hot coffee from cold brew concentrate
  2. Heating up already diluted cold brew coffee

The first method is definitely a far better option. All you have to do is add hot water (or hot milk, if you like) to your cold brew concentrate. 

It’s better because by doing it this way, you don’t risk overheating it and having it turn bitter.

On the other hand, when you heat up diluted cold brew on the stovetop or in the microwave, this is always a possibility. Although, the chances of this happening with cold brew are much lower than with regular coffee that has gone cold.

Why is that?

Well, the cold brewing process slows down the oxidation of the coffee. That means that when you heat it up, its flavor changes a lot slower. 

It will still change a little bit though, which is why adding hot water straight to the cold brew concentrate is a better way to go about it.

The Bottom Line

While technically you can reheat coffee and drink it safely, you really shouldn’t.

It’ll completely change the taste of the coffee, leaving you with a bitter abomination.

Instead, use a thermos to keep your morning cup of joe warm for longer. And always remember to warm your coffee pot and mug up before you use them.

By doing these things, you’ll be able to enjoy your warm brew all morning long. 

If we’re talking about cold brew coffee – you’re all clear. Heating cold brew won’t change the flavor of the brew anywhere near as much as heating regular coffee.

That said, adding hot water to your cold brew concentrate is a much better route to take than heating already diluted cold brew coffee.

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Viktorija Jovanovic
Viktorija is a trained barista and chronic iced coffee addict. Aside from great coffee, she loves photography, road trips, and spending time in nature with her dog, Bane.