Okay, so what we’re talking about is coffee that has been brewed hot and slowly reaches room temperature. We’re not talking about cold brew coffee or hot brewed coffee that is quickly chilled, say with ice. Now that we got that out of the way, here is what happens. From USA Today: “As hot coffee cools, these lactones break down to become carboxylic and chlorogenic acids. These acids present themselves via a bitter/acidic flavor in the cup,” he said. “This combined with the oxidization that is also occurring as coffee cools down just makes for a super unpleasant taste most […]