Why Does Reheated Coffee Taste So Bad?

crazy by Editorial Staff | Posted on July 1st, 2021

A cup of Joe has a short shelf life. You’re enjoying the lovely flavor and aroma of hot coffee one minute, and then it’s virtually ice cold the next.

You choose to heat it in the microwave to get a revolting taste on your tongue. The drink had become even bitter, worse than when you started with the drink.

bad coffee

Coffee culture

Cafes with a pot of filtered coffee brewing up all afternoon are largely extinct. They have been replaced by artisan roasting houses, where each bean is hand-selected and ground separately. This is accomplished with small hammers before being paired to the melted glacier water that best matches its flavor profile.

To their credit, you can tell the difference. If the bean has been roast excessively, the grounds have been burnt by too-hot water, or the coffee has just been produced carelessly, the coffee can be quite bad.

However, if you’ve taken the time to prepare a good cup and utilized good beans, the distinction is simply down to personal preference. You will undoubtedly find extremely wonderful vintage or organic wines that cost a big buck in a similar vein and should only be consumed on exceptional occasions. This isn’t to say that table wine can’t be good and drinkable with a cheap meal.

What happens when coffee gets cold?

Some people wonder why coffee tastes wonderful when it’s hot, fantastic when it’s cold (iced coffee), and dreadful at room temperature. It’s a fair question because stale coffee may be pretty unpleasant. According to one idea, whether you drink hot or cold coffee, your taste buds do not react to the bitterness of the coffee.

Instead, it is simply the temperature-induced response. When the coffee is lukewarm, the taste receptors are more sensitive to bitterness. Another factor to consider is the aroma of the coffee, which is such an important component of our taste experience.

When the coffee is cold, the smells are not as stirred, and we don’t appreciate the fragrance as much, leading our brain to feel that the taste is unpleasant when it is very similar. Another issue to consider is whether or not we add milk to our coffee; lukewarm milk does not taste as wonderful as hot or cold milk.

What causes reheated coffee to taste bad?

When coffee is reheated, the chemicals react much more, making the drink far too bitter. Continue reading to learn why reheated coffee has a bitter taste.

When coffee beans are roasted, the chemicals and acids in them react immediately to heat. When heated, the chlorogenic acid in the beans degrades into quinic acid. The acid imparts a slightly acerbic and bitter flavor to coffee.

Coffee that has been freshly brewed contains more delightful flavors than bitter ones. However, reheating it more than once causes more quinic acid to be produced, making the coffee taste bitter. You’ve surely noticed that the delectable aroma fades after reheating.

Several factors will influence how effectively your coffee reheats;

  • The bean roast
  • The quality of the originals beans
  • How long it sat out before it was stored
  • How well it was stored 
  • How it was brewed

What about coffee pots that warm your coffee through the day? Do they also make coffee taste bitter?

Yes. Any brewer or carafe that uses heat to keep the coffee warm (rather than simply insulating it to preserve temperature) will pull out the bitter, metallic flavor.

Because they held the brewed coffee on hot plates after brewing, these old-school diner coffee pots fell out of favor. Rosenberg claims that brewed coffee tastes best when drunk within the hour of brewing.

Is it true that all varieties of roasts get bitter?


All type of roast becomes bitter when reheated. Bitterness will be more pronounced in dark roasts. Because the coffee has previously been treated to strong heat during roasting, it contains more quinic acid. Bitterness increases as the number of quinic acid increases.

Is it harmful to our health to microwave coffee?

Some individuals are curious whether reheating cold coffee is harmful because they have heard horror stories.

Nevertheless, scientific research has discovered that unless you place your eyeballs straight to the door of a microwave while it is on, there is little likelihood of it damaging you.

Then the question changes from whether or not microwaved coffee tastes unpleasant, but if microwaved coffee is potentially hazardous.

The answer is no, it does not.

Microwaves are high-frequency radio waves, and the effect they have on food is not carcinogenic. Microwaving a  cup of coffee causes the molecules to move quickly as they heat up, but it does not affect their fundamental structure. It isn’t a massive hadron collider.

What should you do?

If you’re making coffee on the go, you’ve probably got an insulated cup or convenient non-metal thermal mug to help out.

Because the liquid is exposed to chilly air while drinking coffee from a mug, it cools down faster.

If you work at home, try using your thermal flask to keep your coffee warm.

Other Products to Keep Your Coffee Warm

Do you always let your coffee cool? There are products available nowadays that will keep your coffee at the proper sipping temperature:

Mug with a lid

A cup with a lid is a simple method to keep your coffee warm. A reusable mug, for example, can preserve your coffee nice and toasty for a bit longer. This will not leave your coffee as warm as a thermal cup, but it is better than nothing.

Thermal mugs

When looking for the best thermal cup to keep your coffee warm, seek an auto-seal locking lid that is also easy to clean. Search for a double-wall vacuum-insulated model, particularly made of stainless steel, to keep drinks warm for longer.

Stainless steel will be more expensive, but if heat retention is important to you, this is the thermal mug for you.

Most manufacturers claim that drinks will be kept hot for hours.

Check out all the best reusable mugs you can buy

Smart mug

Using the Ember smart mug as an example, it is predicted that the mug will survive for 2 hours on battery when used on the move with a predetermined temperature. The ambient temperature, pour temperature,  and intended temperature are all factors that may affect battery life.

Smart mugs communicate via an app or device. You will be able to check both temperature and your caffeine use as a result of this. If the drink becomes too hot, an LED on the side will alert you.

Smart cups must be hand-washed after use.

Drink iced coffee instead

Is it not bothered by the heat? Drink it cool. It wasn’t brewed cold, but it is now!

Simply not warming it up will make it taste better because you won’t risk breaking down the amazing flavors and fragrances.

You’re ready to glug it, especially if you’ve taken the time to preserve it in a bottle.

Pour it over ice with a little flavored syrup for an iced coffee!

How to prepare your containers

Coffee’s flavor and aroma fade as the beverage cool. It’s a good idea to preheat the container holding the coffee.

Slosh a small bit of hot water into your insulated cup, then pour it before putting hot coffee into it. The high temperature can be maintained in this fashion.

Try making smaller quantities of coffee

Instead of making a large cup that you cannot finish, try brewing small batches that you can enjoy hot. It’s not like you’re going to spend an hour brewing any amount!

Here’s more way to reheat your coffee


Is it possible to reheat coffee in the microwave?

Yes, coffee can be heated in the microwave. However, the flavor of your coffee may vary when reheated.

How long does it take to heat coffee in the microwave?

I don’t particularly appreciate wasting food in general, so sometimes I microwave my coffee despite losing scents and flavors.

It will take about 45 seconds to reheat half a cup of coffee. Of course, this depends on your microwave, so if it’s not hot after 45 seconds, repeat reheating for 10-second intervals until it’s at the desired temperature.

What is the ideal temperature for reheating coffee?

When your coffee machine does all the warming up for you, you never have to worry about how hot your coffee is when you make a fresh cup. When reheating, you have complete control over the heat.

Too hot and you spoil it, and brewing Joe is also harmful.

The perfect temperature for coffee has long been a source of contention in the coffee community.

Is reheating coffee safe?

Reheating your coffee is quite safe. You’ll most likely merely notice a difference in taste, with no negative consequences.

Is it possible to reheat leftover coffee?

Yes, there are several methods to reheat leftover coffee. You can brew it, boil it, or microwave it.

Is it safe to reheat day-old coffee?

Any coffee that is 12 hours or older should not be reheated.

Is it true that warming coffee destroys caffeine?

There is a lot of contention on this. As a general rule, heat degrades nutrients, so it stands to reason that reheating or making your coffee especially hot at the start would affect caffeine levels.

According to our research, most experts agree that warming coffee has little effect on caffeine; however, there are self-proclaimed coffee lovers who would argue otherwise.

Is it possible to reheat coffee with creamer in it?

Dairy scalds quickly, especially when sugar is present, and it is also prone to curdling. Heating it too rapidly is a recipe for trouble, so stick to the low – medium heat rule.

You also want to make sure your coffee hasn’t been sitting out for too long, as dairy and other dairy-like things spoil faster than black coffee.

You can reheat coffee with creamer safely and confidently. Just make sure you haven’t allowed that cup of coffee and crepe go to waste.

Disclaimer: This post contains affiliate links, which means I may receive a small commission, at no extra cost to you, if you make a purchase using these links. Last update on 2023-06-08 / Affiliate links / Images from Amazon Product Advertising API

Disclosure: No compensation or free products were received in exchange for writing this review.


Editorial Staff

The editorial staff at Crazy Coffee Crave is a team of coffee enthusiasts & Baristas who enjoy the one thing we all think about as soon as we get up in the morning. Trusted by thousands of readers worldwide.