A coffee bean is well designed to keep it’s contents safe from the elements and well preserved. There is loss of content during roasting. However, once the beans are ground, all the oils and flavors begin to escape significantly….and immediately. So, even with the most careful attention to saving the escaping essence of coffee taste, a good deal of the flavor is lost as the coffee sits on a shelf. This is true whether you are using an espresso coffee maker, a single cup coffee maker or something in between. And the longer the grinds wait before brewing, the greater the loss of flavor.
Freshness– The best possible flavor and taste that comes from a particular kind of bean, is produced when the brew is started immediately after grinding. This is what happens with the use of a coffee maker that has a grinder. The grinder puts the ground coffee directly into the brewer.
The distinctive flavors of different beans are more pronounced and identifiable when using true, fresh ground coffee. Immediate brewing is essential to getting the best flavor.
Control– The fineness of the grind affects the taste quite a bit. Now, with a grinder, control of the grind shifts to the coffee drinker instead of being decided by a coffee seller. Some grinders offer options for fineness while others have one grind. But in any case, the coffee drinker is in charge of the grind.
Cost– Although not dramatic, some cost savings can be achieved in buying coffee beans instead of ground coffee. On occasion, beans will be cheaper than ground coffee.
Extraction– A lot of carbon dioxide is released from coffee beans during roasting. And this process continues after grinding. Losing too much CO2 means diminished taste.