When brewing fresh coffee using hot water methods like those used with a Phin filter or a French press, you may notice a foamy, bubbling substance appear after pouring hot water on the coffee grounds. While this may appear strange to those who are just getting started with brewing their own coffee at home, for the everyday barista, this coffee bloom is a good sign that the coffee you are using is fresh and high quality.
Put simply, a coffee bloom is the rapid release of gas trapped in coffee beans when the coffee grounds come in contact with hot water. This gas is carbon dioxide which has been trapped in the coffee beans during the roasting process. Once coffee beans are finished roasting, however, they slowly begin to release the carbon dioxide naturally over time in a process known as “degassing.” When hot water comes in contact with the beans, this process of “degassing” is sped up, resulting in the coffee bloom.
When left un-brewed, coffee beans typically take a few weeks to completely lose all of their carbon dioxide. This means that the freshest coffee beans will have the most dramatic coffee bloom, and conversely, the oldest coffee beans will have little to no bloom at all. This means that the coffee bloom itself can be a sign to know whether or not your coffee beans are fresh or stale, and whether or not your brewed coffee will be at its most optimal flavor.
There are a few other factors which can affect a coffee bloom. These include temperature and humidity — higher storing temperatures and higher humidities can speed up the degassing process — as well as the roast level of the bean, the bean’s origin, and the hardness of the bean. In general, however, using coffee beans that have been freshly roasted will always yield a strong coffee bloom, and subsequently a fresh tasting cup of coffee.
Using hot water brewing methods, like those with Omni Bev’s Phin Filter and Portable French Press, will always yield a coffee bloom when the beans used are fresh. All of Omni Bev’s coffee beans — Arabica, Robusta, and Omni’s Signature Blend — maintain high levels of freshness, as they are all sourced from family farms in Da Lat, Vietnam, and roasted in California. Using Omni Bev’s beans will yield a perfect bloom and delicious cup of authentic Vietnamese coffee every time.