Explaining Why Reheated Coffee Has a Murderous Flavor and What to Do Instead

There's a finite amount of time a hot cup of coffee has when you work from home; you pour yourself a mug, set it next to your computer so you don't burn your tongue, and an hour later, the coffee is cold. You nuke it for a few seconds in the microwave, hold the cup to your lips, and grimace. The flavor is sour and unpleasant. The kind of bitterness that makes you wonder if a vial of poison was poured into it, Romeo and Juliet style.

Is this something you’ve heard before? You've probably had this same experience reheating coffee in the microwave, on the stovetop, or any other method. Reheating coffee, no matter how you do it, releases compounds that make it taste noticeably bitter. Experts we consulted shed light on the causes of this behavior and provided us with some practical advice for breaking the cycle.

Now that you spend more time than ever working from home, it's imperative that you educate yourself so that you never again have to suffer through reheated coffee.

Before your coffee beans are even roasted, their DNA is made up of acids and compounds that are just waiting to turn bitter when they are heated up, as Stumptown Coffee's director of education and training operations Emily Rosenberg explained to HuffPost.

Chlorogenic acids, found in green (unroasted) coffee, are converted into quinic acid (tastes like quinine in tonic water) and caffeic acid during the roasting process. Quinic acid and caffeic acid both have a bitter, astringent flavor that is even more pronounced than chlorogenic acid's.

According to Rosenberg, "all coffee has some bitterness." However, the bitterness is offset by the abundance of sweetness and acidity in freshly brewed coffee, making for a nuanced and satisfying flavor. ”

Reheating coffee causes more of that quinic and caffeic acid to be produced, making it taste "even more bitter, astringent, gnarly," as described by Rosenberg.

In the words of Blue Bottle Coffee's director of coffee culture, Michael Phillips: "It all boils down to two words: volatile compounds." They are abundant in coffee. All of these things contribute to the wonderful flavor and aroma of freshly roasted and brewed coffee. However, the name itself suggests that they are prone to breaking apart, and this is indeed the case. Reheated coffee loses much of its flavorful qualities and instead tastes more like the bitter substances that survive the heating process. ”

Reheating coffee causes the bitter, floating particles to continue to brew, especially if you used a French press.

As Rosenberg put it, "that coffee is sitting in there and swirling around, and it'll almost continue to brew, effectively, and you're extracting flavors that you wouldn't necessarily want to continue to extract."

To put it in perspective, here's how Rosenberg put it: "You're cooking an already finished product." You wouldn't want to dry out a cake and ruin its flavor and texture by baking it again. A similar way of looking at coffee as a final product is as a beverage. It will change flavor if you keep cooking it. ”

Rosenberg responded with a positive. The bitter, metallic taste is brought out by any brewer or carafe that actually heats the coffee to keep it warm (rather than just insulating it to maintain temperature). ”

In reference to the decline of the diner coffee pot, he explained, "This process is why those old-school diner coffee pots went out of fashion because they kept the brewed coffee on hot plates after brewing." "The hot plates did their job of keeping the coffee hot, but at the expense of making it taste so awful that it has become a trademark of diners everywhere." ”

The flavor of freshly brewed coffee, according to Rosenberg, is at its peak within the first hour to 90 minutes.

Reheating causes a gradual increase in bitterness in all roasts. However, according to Rosenberg, the bitterness of a dark roast coffee is amplified.

Dark roasts have more of the bitter-tasting quinic and caffeic acids because they've been subjected to a higher temperature during roasting than lighter roasts, which is why we just discussed this.

Some recommendations have included using a microwave at 80% power or heating it very slowly over a stove. But Rosenberg proposes a solution so simple that you'll feel ashamed that you didn't think of it yourself.

Rosenberg speculated that people who work from home would already have a thermal to-go cup or an insulated cup. You might not think to use it at home, where your mug is more comfortable, but it's worth considering for when you're out. which allows more surface area to come into contact with the air and thus cool down much faster; I'll just pour it into the to-go mug I usually use when I get coffee from a cafe. ”

Phillips also suggested that, but with the disclaimer that a thermos won't last you all day.

His advice: "The cup will still start to falter around 30 to 45 minutes in terms of the best flavor, but it will be piping hot the whole time." Professionals, in general, prefer their coffee at cooler temperatures because of the way the flavor develops. Personally, I find that the sweetness of coffee is best experienced when it has been allowed to cool to about 125 degrees. ”

It's important to preheat the brewing vessel, whether you're using a Mr. Coffee or a manual brewer, according to Rosenberg. Coffee To get a warm pot, boil some water in a kettle, pour it into the pot, give it a good stir, and then dump the water out before brewing. The same can be said of the cup you're using to drink from. Slosh some hot water around in your mug to keep it hotter for longer.

When working from home, it's tempting to brew a pot of coffee and be done for the day, but remember that you won't be able to take nearly as many breaks. And if you're trying to break out of a rut, making multiple cups of coffee at different times of the day can be a great way to do so.

A small cup of coffee in the morning, followed by a return to the kitchen at 11 a.m. m , Rosenberg advised, "and brew a little bit more." "Brewing more often with smaller amounts will keep it hot and give you rest breaks throughout the day. ”

She found solace in the ritual of making coffee, saying, "The process of brewing coffee is something that is very comforting to me." "It's a pleasant pause from whatever I was doing to focus on the here and now. It's something I enjoy and value greatly, especially at this time. ”

While making sourdough bread at home has become increasingly popular during the coronavirus pandemic, Rosenberg argued that brewing coffee takes much less time but yields similar benefits.

Coffee is so easy to make. Unlike baked goods that call for ten or bread that takes hours and hours to make, "it's just two ingredients," she said. As the saying goes, "With coffee, the stakes are pretty low." ”

In that case, how often does Rosenberg give in and heat up her own food in the microwave?

She explained, "I don't have a microwave because I don't own one." That choice is off the table. ”