Can You Reheat Coffee In A Microwave? : A Long Burning Question Answered

It’s very easy to forget about your cup of coffee while it sits and cools down on the counter while you take care of either household or office work. But you don’t want to waste …

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It’s very easy to forget about your cup of coffee while it sits and cools down on the counter while you take care of either household or office work. But you don’t want to waste a fine cup of coffee beans you spent so much time brewing. So you decide to reheat it in your microwave. But, you must ask yourself that “can i reheat coffee in a microwave?” Let’s just say:

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Today, we’ll be looking into every aspect of reheating your coffee in a microwave and decide if it’s really worth it to heat your coffee back up before brewing a fresh batch.

Can You Reheat Coffee In A Microwave?

The short answer is “Yes. yes, you can reheat your coffee in a microwave.” Now for the long answer

It mainly depends on what part of the world you are living in. If you live in a colder environment, it shouldn’t be much of a hassle to reheat your coffee while retaining most taste.

You still need to consider the time limit of the coffee. A cup of brewed coffee starts losing its temperature and flavor after the 30-minute mark. And if you leave it for hours, the coffee can lose all its flavors while becoming more acidic and stale tasting because of the oils.

So if you are reheating 30 minutes of old coffee, you still have a chance of reviving your coffee. But I wouldn’t strongly recommend microwaving coffee that’s been sitting on the counter for hours.

Can You Refrigerate And Reheat Your Coffee?

Reheating refrigerated coffee is actually a horrible idea. Instead, you can make iced coffee or a standard cold brew with refrigerated coffee.

But when you reheat refrigerated black coffee, it loses all the taste and aroma, and even the volume is decreased so much that it becomes apparent to your taste buds.

Now, what if we added milk into the mix?

Is Reheating Coffee With Milk A Bad Idea?

You can reheat coffee with milk in it, but whether it’s going to taste good afterward is a bet you don’t want to take on.

Milk has enzymes that can go bad after a couple of hours from being in contact with open air. So if you are planning to heat up hours of old coffee mixed with milk, you’ll have a spoiled, sour mess in your hands that you really shouldn’t drink.

Drinking spoiled milk is already a bad choice. And if you drink coffee with spoiled milk in it, you can have issues like vomiting, stomach sickness, and mental disgust.

Can You Heat Cold Brew Coffee?

Do keep in mind that cold brew and iced coffee are two different things entirely, and it’s better to distinguish between them to realize which one you can reheat.

It’s perfectly normal to reheat cold brew coffee, as it’s just coffee steeped in room temperature water. The very purpose of cold brew is to reheat it in small portions so you can have a hot cup of coffee later on.

Here are 2 methods you can use to warm up your cold coffee:

Method #1:

  • Heat up water, and pour the hot water into your mug
  • Swirl it around in the mug to heat the mug up
  • discard the hot water in the mug once it’s heated up
  • Pour the cold brew in your mug, fill it halfway
  • Fill the other half of the mug with boiling water that’s been sitting for around 5 minutes

Method #2:

  • Heat up water to preheat your mug
  • Preheat the mug
  • Once it’s heated, fill the mug halfway with cold brew
  • Unlike before, fill the other half of the mug with steamed milk

On the other hand, Iced coffee is a traditional coffee brew poured over ice, so it takes on the temperature of the ice and becomes really, really cold.

Microwaved iced coffee leaves an awful taste in your mouth, as a microwave changes all the chemical compounds of the coffee.

What Happens When You Microwave Coffee?

Would you believe it if I told you that you’re doing science stuff every time you’re heating up a cup of coffee in a microwave?

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When you microwave your cold cup of coffee, you don’t just increase the temperature of the liquid; you change the entire chemical makeup of the beverage.

Coffee is supposed to be a one-time use kind of beverage. So it’s better to drink it as soon as you brew it and not to try and heat it back up after a few hours.

If you don’t want to waste your precious leftover coffee, it’s better to turn it into iced coffee for later drinking. But if your coffee has already gone cold, and you want the taste of fresh coffee, it’s better to brew a fresh batch.

Hey, Check our piece on truth about vegan coffee. You’ll love it.

Even The Cold Coffee May Not Taste That Good

As we mentioned earlier, coffee has different enzymes in it, along with thousands of volatile compounds. Even when you don’t heat your coffee up, these aromatic compounds start deteriorating over time.

When you put your coffee in a microwave oven, you only make the process happen faster. Even if you reheat it entirely, it’ll adapt to acidic and bitter tastes.

If you’re new to the coffee world, you won’t detect the subtle differences and be happy with the result. But if you are a coffee connoisseur, it’s better to brew a fresh cup of coffee and forget about the staleness of the past brew.

Does Microwaving Coffee Take Away The Caffeine?

It’s natural to think it can happen, considering the chemicals in coffee can start breaking down. But that isn’t the case.

Though your coffee loses its original aroma and flavor profile after being left out for a long time, it can still contain the same amount of caffeine as a fresh cup of coffee.

Best Way to Reheat Coffee

If you still wish to reheat your coffee, microwaving it may not be the best option.

Instead, use the stovetop method to heat up the coffee at a low-temperature heat over a longer time. Doing so lets you retain most of the flavor and aromas of the coffee. Here’s how you do it:

  • Grab any pan from your kitchen
  • Put the coffee in the pan
  • Set the pan on the stove at a low temperature
  • Slowly stir it till the coffee reaches the desired heat level

Things to know before microwaving coffee

Microwaving coffee isn’t necessarily a great solution. It’s more of a quick solution when you have very little time in one hand and semi-cold coffee in the other.

So if you absolutely have to reheat your coffee, here are a couple of things you need to remember.

Thing #1: Use A Cup That Is Microwave-Safe

If your cup isn’t microwave-safe, you can have a fire hazard in your hands, along with a spoiled microwave with coffee rolling all over in it.

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If you have a cup not labeled for microwave use, there’s a way to test it.

Fill the cup halfway with water, and heat up the cup for 30 seconds. If the water is hotter than the cup itself, then you’re good to go.

Also, don’t try to lid your coffee cup when microwaving it. The air trapped inside the cup can make the lid melt. Worst case scenario, your coffee mug can explode.

Thing #2: Don’t Use Too Much Heat

When heating up the coffee in the microwave, always use a medium heat level to not warm up too fast. That way, the coffee starts going towards the tasteless territory. Don’t forget to stop it and stir a little every 30 seconds, so the temperature is evenly distributed.

Having fun Nomies? Check out our piece on caffeine amount in coffee beans.

Options You Can Choose To Keep The Coffee Warm

If you have a short attention span and are always forgetting to keep your coffee warm, there are other options you can consider that can keep your coffee warm for you.

Option #1: Mug with a Lid

The most simple form of the heating mechanism of them all, a simple reusable mug with a lid, can help you keep your coffee warm. Of course, 30 minutes isn’t a really long time, but it’s still better than nothing.

Option #2: Thermal Mugs

Thermal mugs have been around for years, and it’s a better option for your coffee warmth needs. If you plan to brew coffee at home and take it to work to drink, thermal mugs are the best choice.

As long as you look for mugs with an auto-seal lockable lid and are easy to clean, you’re golden. However, if you’re planning to keep your coffee warm for several hours, I suggest investing a bit more and getting a stainless steel mug that has a double-wall vacuum insulated inside.

The extra pressure on your wallet may feel bad at the start, but considering you can keep your coffee heated for over four hours, it’s a solid investment.

Option #3: Smart Mug

This is the most expensive, safest and tech-savvy option available in the market.

The battery life of a smart mug depends on several different factors, such as

  • Pouring Temperature
  • Ambient Temperature
  • Desired temperature

The best part of it all is you can use your phone or smartwatch to control the temperature of the mug. In addition, there’s an LED display on the side that’ll let you know if your coffee is too hot to drink. It even goes as far as tracking your caffeine consumption.

Is Reheating Coffee Bad For Your Health?

There’s an ancient myth floating around the internet, sometimes being echoed in coffee forums still, that is, “drinking reheated coffee gives you cancer.”

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Seriously, don’t be scared by it. It’s just a rumor that has no scientific proof behind it.

Microwaving your coffee can take away the original taste, aroma, and other beneficial properties from it, and that’s a fact. But it won’t turn your coffee into a material so toxic that it gives you cancer.

The only way reheated coffee can impact your health is your mental health after drinking a bitter soulless coffee that irritates you even more.

Had fun reading? You’ll love to read our piece on why mormons don’t drink coffee.

Bottom Line

Despite having a fair share of myths and rumors around it, reheating your coffee in a microwave is not a very bad idea. Reheating coffee takes away from the overall taste and freshness of the coffee, but it doesn’t pose any threat to your body.

Here’s to hoping your coffee stays tasteful for longer, and you stop forgetting to drink your coffee while it’s hot.



How Long Can I Store My Coffee?

Depending on which medium you are storing your coffee on, you can store a cup of hot coffee and retain its heat for up to 6 hours.

How Do You Reheat Coffee in the Microwave?

If you want to reheat coffee in the microwave, place your cup/ mug of coffee in the microwave without a lid, and stop it to stir it every 30 seconds to distribute the temperature evenly.

What Is the Best Way to Reheat Coffee?

A better way to reheat coffee is to put your coffee in a pan, then put the pan on the stove to heat it back up at a lower temperature.

How Do You Reheat Coffee, and Is It Safe?

I personally reheat coffee in a microwave-safe mug in a microwave, and it’s safe.

When Does Coffee Become Acidic?

When you leave the coffee out in the open for a long time after brewing, the components of the coffee start breaking down, and the coffee becomes more acidic.

What Is the Perfect Temperature for a Cup of Coffee?

The most perfect temperature for an ideal cup of coffee is between 195-200F.