Not all coffee capsules are created the same. Good coffee capsule and pod production requires more than just roasting, grinding, and packing coffee into pods and capsules. It also requires an extra step to make sure the density of the ground coffee is optimal for capsule and pod brewing. This process is called densification, which occurs immediately after grinding. To understand how densification works and its role, we must look at the following:
The coffee particles’ shapes when they exit the grinder and how to optimize their shapes for greater density.
The use of water pressure in capsule and pod coffee makers and how densification acts like tamping to create better extraction.
Coffee Particles' Shapes as They Leave the Grinder
Coffee particles are not smooth and spherical when they exit the grinder; instead they are jagged and non-spherical. The non-spherical coffee particles tend to use up more space than necessary to fill each capsule—creating empty space which should contain coffee particles. This results in a below-optimal capsule density and leads to a less flavorful, under-extracted cup of coffee during brewing.
Densification is not a new concept. Tamping an espresso is basically a form of densification. In the case of tamping, it not only serves to fit more coffee (and dissolvable solids) into the espresso machine portafilter, but also provides the resistance needed for the water pressure to forcefully extract the flavor and oils trapped inside the coffee particles.