Once you start exploring coffee, and recognizing that it’s simply drinkable chemistry, you inevitably wonder if there is an ideal way to re-heat coffee once it gets cold. Stove, microwave, geothermal effusion??? What’s the best way to warm up a cup without ruining flavor?
Sorry, but I’m here to bum you out. There’s actually really no good way to re-heat coffee. When coffee brews, the water extracts particles and color. That sediment at the bottom of your cup? Lots of tiny, tiny pieces of coffee. And heat enhances that extraction process, breaking coffee down further, yielding higher concentrations of coffee particles in the water.
So when you nuke a cup of coffee, or gently warm it in a sauce pan, you’re still taking those already-extracted coffee particles and breaking them down further, getting into the icky, bitter center of the molecules and releasing it into the drink. Once a re-heated cup cools off a little, you’ll probably notice sharp flavors and a distinct lack of aroma, all the delicate top notes having been shredded by repeated temperature changes.
My advice? Learn to appreciate cooled-down coffee (you should, you should). But if you HAVE to have your coffee hot, and you don’t have time to slowly swirl it on low heat in a saucepan on the stove (the true best way, tbh), then throw it in the microwave, drink your destroyed coffee and get on with your life. Quit reading articles about it, you’re gonna just nuke it anyway. As always, when it comes to life and coffee, just do you, boo.