title_body: Why some coffee pods are under pressure?
upvoted_answer: Inert gases are known to be chemically stable; they don't react with materials around. Based on that fact Ernesto Illy, the son of the founder of the famous coffee roasting company, invented the method of filling a can of roasted coffee beans with pressurized inert gases. Many years they held the patent for this method and still pressurized roasted coffee cans are the fingerprint for that company. This method is known to protect the roasted beans for a longer period; however it's not magical. So, the beans will stale eventually.