Let Freshly Roasted Coffee Bloom
Freshly roasted coffee contains many aromatics and gasses that add to its aroma and flavor. They also, however, have a lot of carbon dioxide, which produces a sour taste. Letting coffee bloom gives this carbon dioxide time to escape so that it doesn't interfere with your brew's taste.
Coffee Needs to Degas After Roasting
Coffee beans contain high amounts of carbon dioxide after they're roasted, and they need time to degas. Degassing is the process of carbon dioxide leaving the beans. Although most carbon dioxide is released in the hours immediately after roasting, it takes up to two weeks for all of the gas to leave the beans. If brewed within two weeks of roasting, beans will still have a lot of carbon dioxide that must be released during the brewing process.
Fresh Coffee Blooms When Brewed
Brewing coffee accelerates degassing. As hot water comes into contact with the grounds, carbon dioxide is quickly extracted. Bubbles form as soon as the water hits the fresh grounds, producing the "bloom."
The bloom will last for 30 to 40 seconds, depending on how fresh the coffee is. If the beans were roasted within two days, the bloom will be closer to 40 seconds. Coffee that has been degassing for one to two weeks will have less carbon dioxide in it, and the bloom will be around 30 seconds.
Let Your Coffee Bloom for 30 to 40 Seconds
No matter how you make coffee, it's easy to let coffee bloom. Dampen the grounds with a little water before you brew them. Let them sit for 30 to 40 seconds, at which point the bubbling should begin to subside, and then make your coffee as you normally would.
By taking a few seconds to let your grounds bloom, you'll ensure that carbon dioxide doesn't interfere with the coffee's desirable qualities. Freshly roasted coffee is full of lively, aromatic compounds, but carbon dioxide's sour taste will overshadow these if it's not released first. Make sure you're able to taste all of those aromatic and flavorful compounds the next time you brew freshly roasted coffee by giving it a chance to bloom.