What is the purpose of the "bloom" in coffee brewing?

The purpose of the "bloom" in coffee brewing is to allow trapped gases, particularly carbon dioxide, to escape before the full extraction process begins. When coffee grounds are first saturated with water, the release of these gases creates a bubbling effect, known as blooming. This is particularly important for freshly roasted coffee, which can retain gases from the roasting process. If these gases are not released, they can hinder water from fully interacting with the coffee grounds, leading to uneven extraction and potentially flat or sour flavors in the brewed coffee. By allowing the bloom to occur, the brewing process can achieve better flavor extraction, resulting in a more balanced and enjoyable cup of coffee.