For a couple decades or more I was completely happy buying roasted, store-bought beans, grinding them myself, and making my coffee. The ONE major point that sold me on roasting green beans at home was roasters saying store-bought coffee beans taste dead and flat because too much time has passed since the beans were roasted. Fresh roasted and ground beans taste alive and fresh. Why?
When beans are roasted, the gas CO2 is produced and trapped in the bean. The gas contains flavor, but the longer it has been since the coffee was roasted, the more the bean degasses. Think of it like a soda pop. You open a 2 liter bottle of soda pop and don't drink it all. Into the fridge it goes and two weeks later you decide you want some more. It still contains the flavor of the syrup in the soda pop, but doesn't taste any where near as lively as when you first opened it because the CO2 has degassed from the solution into the air from the first opening. Fresh roasted coffee doesn't taste "fizzy," but it definitely tastes more "alive" than the store-bought beans.
Recently I've been using up some store-bought, Mexican Organic beans for a second cup of coffee with my lunch. I got the idea of taking pics to compare the store bought to fresh home roasted. The "liveliness" of the beans is apparent by the "bloom" of the coffee, which is the off-gassing of CO2 trapped in the bean from the roasting process. As stated above, that gas contains flavor. When the ground coffee is exposed to hot water at the proper temperature, the grind releases the gas and the flavors contained within.
Below are the comparison pics of the store-bought and ground Mexican Organic beans to the recently roasted (2/13/18) Costa Rican beans.
Getting ready to brew some coffee with my Clever Dripper and 200F hot water.
First pour: merely wetting the coffee to start the "bloom" process.
Store bought Mexican Organic coffee beans. Note how the surface has some gas, but is relatively flat compared to the second picture.
Fresh roasted Costa Rican coffee, first pour. Note how the surface appears more rounded with more bubbles of CO2.
Second pour: approximately 20-30 seconds after wetting the grounds, slowly pour water over the beans to the desired level. In the first picture of the store-bought Mexican Organic, there is still some gas being released, but nothing like the second and third picture of the fresh roasted Costa Rican coffee.
Store-bought Mexican Organic.
Fresh roasted Costa Rican coffee (following two pics)
Put the lid on the Clever Dripper, brew four minutes, drink and enjoy.
Disclaimer: I take no responsibility for the impact on Global Warming due to the release of CO2 greenhouse gas from making my daily morning and occasional afternoon coffee.
Have a GREAT day!
Ray