What does the term "bloom" refer to in coffee brewing?

The term "bloom" in coffee brewing specifically refers to the initial release of gas that occurs when hot water first comes into contact with coffee grounds. This process is crucial, especially when brewing with methods like pour-over or French press.

During the bloom phase, carbon dioxide that has been trapped within the coffee grounds is released. This gas is a byproduct of the roasting process and can hinder the extraction of flavors if not allowed to escape. By allowing the coffee to bloom for about 30 seconds before continuing with the brewing process, you improve the extraction and enhance the resulting flavor profile of the coffee. This step is often characterized by the bubbling or swelling of the coffee grounds as they release gas.

Understanding the bloom is essential for coffee brewing because it sets the stage for optimal extraction of flavors and aromas, leading to a more balanced and enjoyable cup of coffee.