What I know is that, for the best taste, one should grind the coffee right before brewing it. Storing ground coffee makes it lose part of its taste, even if there are ways to counteract that effect. However, assume I ground up some coffee and left it in an open conatiner for several weeks. Would the coffee lose any caffeine, i.e. would I feel the effects of the coffee less than if I had brewed it directly after grinding?
If yes, what mechanisms are responsible for this and how does the caffeine leave the coffee?