Ever reach over to take a sip of your coffee, which was previously hot and tasty, and end up with a mouthful of lukewarm coffee that’s anything but delish? It’s not a pleasant experience, but why does coffee taste so bad after it cools down? That’s what a TokTok user named Lys wanted to know and thanks to her clip, an expert is explaining the science behind it.
“Why is intentional cold coffee delicious, but warm coffee that has gone cold disgusting?” Lys asks in the video. Her post has gotten a lot of attention online, including from professional coffee roaster Dan McLaughlin, who responded with a video to teach us about the drink. He explains the chemical processes that affect hot coffee as it cools.
“It’s a chemical reaction,” McLaughlin says at the start of his clip. “Coffee has chemicals in it called lactones, and as hot coffee cools down, a chemical reaction happens where those lactones turn into carboxylic and chlorogenic acid.” And those acids make the coffee taste … yep, you guessed it, more acidic. But it only happens if the coffee cools down naturally over time, not with iced coffee, which is made from an immediate change in temperature and isn’t as acidic as coffee that starts hot and gets cold. And since cold brew was never hot at all, it’s even less acidic.