Have you noticed the layer of “foam” that forms at the surface when hot water and ground coffee come in contact? This top layer of foam is called bloom or crema. Its presence is a sign that the coffee you brewing is freshly roasted. However, there is more to this controversial and delicious-looking foam.

The bloom is mostly made up of CO₂ gas that is trapped inside the coffee bean during the roasting process. Coffee beans have the highest concentration of CO₂ right after roasting, continually degassing thereafter. However, it is not until you pour hot water into ground coffee that most of the remaining CO₂ escapes and forms what we call bloom.

It turns out that if incorrectly brewed, CO₂ released by fresh coffee beans can make coffee acquire an undesirable taste. The CO₂ gas also interferes with the brewing process as it repels coffee from coming in contact with water; this could drive your cup towards under-extracted or acidic territory.

The idea with which we designed VacOne was brewing coffee while keeping the foam or CO₂ out of the finished cup. We theorized that we would have a smoother, sweeter, and more balanced cup with reduced acidity and bitterness if we separated the bloom from the finished cup. Right from the first couple of tests we knew we were up to something...