When coffee grounds come in contact with hot water, they release carbon dioxide and often bubble and expand. Coffee blooming is the act of dampening your coffee bed to provoke this release of carbon dioxide.
When coffee beans are roasted, the organic material of the bean is heated and releases carbon dioxide. Hot water in particular causes beans to immediately release most of their carbon dioxide. This creates a “bloom” when those first drops hit your coffee grinds.
Because CO2 is escaping quickly, it repels water away from the grounds. Carbon dioxide pushing water away is also known as turbulence. This is an issue when you’re trying to extract delicious coffee flavors and textures (the more water to coffee interaction, the more extraction).
We bloom coffee to give the grounds time to make space for water. Additionally, carbon dioxide tastes sour, so blooming prevents CO2 from infusing into your coffee.
How to bloom?
To bloom coffee, start pouring at center of your coffee bed, working your way out to the sides. Pour about two times the amount of coffee you use. Wait 30 seconds for coffee to “bloom” and release CO2. Grounds should be uniformly soaked, but not dripping wet.
