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?


Caffeine has a very very low vapor pressure 9.0X10-7 mm Hg at 25 deg C. Source

Almost none would evaporate.

  • 1
    Did you consider oxidation, too? I checked, but cannot find a nice source if it oxidizes in atmosphere under room conditions.
    – MTSan
    Jan 23 '17 at 6:14
  • It doesn't seem to be readily oxidizable either, so I doubt you would lose much/any.
    – comeauch
    Feb 20 '17 at 11:51
  • 1
    There are several bacterial species that can/will live on caffeine and storing grounds in an "open container" could lead to contamination from such. Feb 22 '17 at 19:11
  • @Chris_in_AK If you have more details, you're welcome to expand in an answer.
    – Ludwik
    Mar 1 '17 at 8:50

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