Pressurization
Coffee in the can: preserving freshness through pressurization
Oxygen is roasted coffee's worst enemy, and roasted coffee exposed to air will lose 40% of its aroma after only eight hours. Another enemy is humidity which also jeopardizes flavor and can cause mold.
It was the challenge of preserving freshness that led Francesco Illy to invent pressurization in the 1930’s. Pressurization extracts the air from the can and replaces it with inert gasses at a higher-than-atmospheric level of pressure. This method guarantees a longer preservation time, maintaining the coffee for over 2 years until it is prepared. At the same time it 'ages' the coffee, improving its aroma over time by causing its volatile aroma compounds to bind with the oils that are contained in the beans. Simple vacuum packing cannot achieve this flavor transformation. The positive pressure exerted by the pressurization method actually forces these aroma compounds back into the coffee so they can be released in the cup. The effect of the aging process is similar in many ways to the development of complex flavors when a fine red wine is aged under proper conditions.