Unfortunately, coffee goes bad. Once coffee is roasted it becomes rapidly perishable. Coffee generally goes bad in two ways 1) Loss of the more volatile enzymatic high notes of the coffee aroma by simple diffusion and binding to degassing CO2 2) Lifelessness and creation of unpleasant flavors due to oxidation. The oils and proteins of the coffee react with an electron donor with an affinity equal to or less then the subject lipids (generally oxygen or sometimes water via hydrolysis) gradually turning the coffee first insipid then rancid. Once oxidation renders many of the oils vapid, the oxidation of linoleic triglyceride is accelerated, changing it from pleasant to unpleasant. Eventually the more saturated lipids in the coffee will succumb to oxidation and give a rancid tinge to the coffee. This lipid oxidation is similar to the fats in a piece of meat going bad.