The Real Reason You Shouldn't Reheat Coffee In The Microwave
Coffee aficionados know the best cup of Joe is fresh, piping hot, and made just the way you like it. But even people who drink coffee every day and are Java experts occasionally get busy with other things, leaving their freshly-made brew unattended and at risk of turning cold and undrinkable. In these case, is it acceptable to chuck your mug in the microwave and give the coffee a little warming boost? Die-hard drinkers will argue absolutely not, especially because reheated coffee, like most food or drink items (except maybe pizza), never seems to taste as good. So, why is reheating coffee such a no-no? Is there a way to do it without wrecking that special, first-taste buzz?
Simply speaking, warming up coffee just isn't a good idea. Todd Carmichael, CEO and co-founder of coffee company La Colombe told Tasting Table: "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." Your best bet, if you are desperately craving a caffeine hit, is to make a fresh pot or turn that cold cup into an iced coffee.
Reheated coffee will taste bitter
Karen Yates from Bean Thinking, explained to The Kitchn, "Several studies note the intensity of the 'roasty-sulfury' odor (which is a pleasant aroma associated with coffee) decreases rapidly after brewing the coffee." The longer a cup of Joe sits out, the worse it's going to taste. Plus, coffee that's been left sitting will taste more sour due to an increase in acidity. Warming it up in the microwave won't reverse the problem. In fact, it could actually speed up the process.
The DNA of coffee beans is made up of different acids and compounds that are on the precipice of turning bitter as soon as they're heated up, Emily Rosenberg, a director of education and training operations at Stumptown Coffee, explained to HuffPost, And these volatile compounds, which combine to make coffee taste great, are ready to fall apart at any moment, added Michael Phillips, director of coffee culture at Blue Bottle Coffee. "When you reheat coffee, all of the good stuff in the coffee starts to disappear and the resulting cup leans toward the more bitter components of coffee that stick around through the heating process," he explained.
Coffee is a finished product that gets worse with each attempt to revive it. Instead, to avoid the problem altogether, consider using your thermal to-go cup at home, or simply heating up your mug before pouring in the coffee, both of which will help keep it warm and fresh.