The Secret To Properly Reheating Coffee

Thinking about reheating coffee that's gone cold? "Just say no" is what any sane coffee lover should tell you. Throw it out, or "in dire straits ... drink it over ice," says coffee-entrepreneur Todd Carmichael. Trust him (via Tasting Table). 

But we're not into shoulds. And, if you're reading this article, you're not into making fresh cups of coffee when you have leftovers begging to be drunk. Is there a way to salvage coffee-gone-room-temperature without creating a bitter, unstomachable brew? Maybe, but you've got to go into it with your eyes wide open. 

Don't take our word for it. Take the words of coffee expert Emily Rosenberg, who told HuffPost that when you roast coffee beans, you convert the beans' chlorogenic acids to bitterer quinic acids. Make it once, and that bitterness is usually balanced out by a bit of sweetness and acidity. That's what makes coffee into the "complex and delicious-tasting" morning pick-me-up that you crave. Reheat it, and you're producing yet more quinic acids. This, in turn, makes for the "gnarly" flavors that you might associate with red-eyed waitresses offering you a sludge-like refill at a reluctantly late-night diner.

There are no ifs, ands, or buts. When you reheat a cup of coffee you'll make it more bitter. If you do it right, you might be able to enjoy it nonetheless.  

Let's lay some ground rules. First, never reheat your coffee in a microwave. Or, rather, only reheat your coffee in the microwave if you're okay with breaking down the coffee's aromas and making it taste both bitter and stale (via The Daily Meal). We'll try hard not to judge. 

Second, stay away from re-heating dark roasts. Dark roasts are naturally "burnt" (and thus bitterer) as they've released more quinic acids in the initial roasting process. If you reheat dark roasts, you're more likely to end up with undrinkable, late-night-diner sludge. 

Got it? Good. Here's the secret to reheating your coffee the right way. The Daily Meal recommends that you reheat coffee over a low temperature on the stove. Doing so will reduce the intensity of the chemical reactions that turn the coffee beans' chlorogenic acids to quinic acids, thereby minimizing the production of any extra bitterness (via Foods Guy). No need to stir, but don't let your coffee boil over, either. Take it off the heat as soon as it starts to steam. Happy drinking!