Should You Reheat Coffee In A Microwave?

It's a familiar scene. Your morning cup of joe has cooled to the point of being undrinkable, but an afternoon slump is approaching, and you're too busy to brew another pot. Faced with what you assume is some perfectly good leftover coffee, you stick the cup in the microwave. One sip later, you swear never to make that mistake again. 

So, why does microwaved coffee taste so bad, and is there another solution?

Next time, when you're faced with a cold cup of coffee, do the right thing and back away from the microwave. According to Todd Carmichael, CEO and co-founder of La Colombe, you should never reheat coffee: "Coffee is a one-time use kind of deal. You make it, you drink it, and if it gets cold, you make some more. Reheating reorganizes the chemical makeup of the coffee and totally ruins the flavor profile. Some things just don't work to reheat, and coffee is one of them. It's always best just to brew a fresh cup."

Carmichael added, "In dire straits, if you're absolutely out of coffee and staring at a cold pot from that morning ... still don't reheat it. Drink it over ice. Trust me, it'll be better."

The folks at Caribou Coffee agree and specify that the microwave is an absolute no go. The company's website states, "When coffee cools, its chemistry changes. Reheating the coffee will further break down the few aromatics left. Your coffee will taste bad." Caribou recommends storing coffee in a thermos or making a new pot.

The Kitchn spoke to Karen Yates of coffee and science blog Bean Thinking for further insight. Coffee's acidity increases as it cools, Yates explained, which leads to a more bitter taste. Both the cooling and the rewarming, in other words, contribute to bad taste of reheated coffee.