Is It Ever OK To Reheat Coffee? We Asked A Coffee Expert

Practically every morning I have to reheat my coffee, and yes, it's completely safe to do, but it's not great for the quality of the drink. Because every time I abandon my favorite mug, and let my coffee go cold, and then zap it back up temp in the microwave, I'm impacting the flavor. And as someone who drinks their coffee with few frills —either black or with just a touch of cream—I can certainly taste the effects that reheating has on my morning caffeine fix.

Read on to learn why reheating makes your coffee taste worse (more bitter to be specific), and the best ways to keep it hot so you don't have to reheat it in the first place.

What Reheating Does To Coffee

You've probably already noticed how reheating affects your morning coffee. That's because it impacts the taste. Coffee can become more bitter after sitting and reheating, and that's not something anyone really wants, but is a natural and inevitable occurrence.

"Unfortunately the main reason that reheated coffee tends to taste bitter is a chemical reaction that is unavoidable, no matter what the coffee is, how you brew it, or how you heat it. This process is going to make your coffee taste more bitter. Even if you don't heat the coffee, but just let it sit for a long time, this is what happens," says Ryan Ludwig of Counter Culture Coffee.

Ludwig went on to explain the science behind how heat can make coffee bitter, and it essentially boils down to the acids found in coffee that impact both its flavor and aroma. Chlorogenic acid is one kind of acid found in the drink, and Ludwig says the problem lies in how it breaks down.

"Chlorogenic acid breaks down over time into quinic and caffeic acid. Heating your coffee speeds up this process, breaking down the chlorogenic acid much faster. Unfortunately, these both taste bitter. For reference, quinic is the same acid you'll find in tonic water, giving it its characteristic bitter flavor," he says.

Does How You Reheat Coffee Make a Difference?

Okay, so reheating isn't doing your coffee any favors flavor-wise, but are some methods of reheating better than others? Kind of.

Reheating of any kind, stovetop or microwave, will contribute bitterness. If you, like most of us, are nuking your cold cup of coffee in the microwave, well, that might just be the best way to reheat it if you have to.

"Heating in the microwave has one benefit: It is fast. Heating your coffee causes all the good tasting and smelling compounds in the brew to escape faster. If you heat over a long period of time on the stove, you'll lose more of that good stuff. So if you must reheat, the microwave is probably the better option," says Ludwig.

The Best Way To Keep Your Coffee Hot

Well, it's not the hot plate on your coffee maker. Those have the same effect on coffee as reheating in the microwave or on the stovetop does. The best thing you can do is invest in a high-quality insulated mug or carafe that can keep your coffee hot for longer.

With the important caveat that, "The flavor is still breaking down little by little over all that time, but you're not speeding it up by heating it," says Ludwig.

Ludwig also notes that there are a lot of good options on the market for insulated mugs, tumblers, carafes. His personal go-to is brewing into a Hario V60 insulated brewer. "It will keep your coffee hot for a LONG time," he says. "I've used Fellow insulated tumblers as well, and left coffee in them all day to find it still hot hours and hours later."

I should probably invest in one soon, because my coffee has gone cold (yet again) while writing this article.