Coffee and Caffeine FAQ

Roasted beans give off carbon dioxide over a period of weeks, but approximately 40% is given off in the first 24 hours. If the beans are ground and brewed drunk immediately then some of this CO2 would dissolve in the water and give a true acid taste. A French press of freshly roasted beans will froth alarmingly - stale beans will hardly froth at all. In addition, the flavors on some beans seem to develop over a period of 2 to 3 days. Thus beans should be left to degas for a day or two. It is not essential. Fresh coffee is not bad immediately. The beans just improve.

Staleness is mostly caused by oxygen getting to the bean (also partly by internal chemical changes.) Probably the best method is to put them in a one-way valve bags. They let the CO2 out but prevent the oxygen coming in. A lot of home roasters use Mason jars (glass bottling jars).

At any point in time you might choose to have 3 or 4 little jars on your kitchen side. Perhaps a light Colombian for all day; a gutsy Java to wake me up; a light espresso blend for straight shots and then perhaps a heavy cappucccino blend comprising Indonesians and robusta for cutting through the milk. None of them will be around for more than a week or so so they will stay fresh. The average commercial roaster might just have got his roasted beans to the shop or the warehouse in the first week.

As a side note I will say that due to the quickness of consumption of home roasted coffee storage is less of an issue than for people who want to keep their coffee for an extended time.