A roasted whole coffee bean is a wonderful, protective package that keeps the coffee oils exactly where they need to be, basically, inside the bean. As long as you don’t play around with the beans the flavor components, which are very delicate, volatile and water-soluble substances, you will be ok. On the other hand, if you break the protective shell, then all bets are off.
Introducing the four great reasons why NOT to buy pre-ground coffee.
1) Contamination – Coffee oils are very fragile, this makes them very susceptible to contamination.
2) Oxygen – After 15 minutes ground coffee loses approximatley 60% of its aroma
3) Moisture- When ground coffee is exposed to moisture the oils start to dilute immediately.
4) Carbon Dioxide Depletion – Carbon Dioxide is important because it is the main way for getting essential coffee oils into the coffee after they are released.
The Answer: always grind your coffee freshly just before brewing. Do this rule and you will be one step closer to paradise in a cup.