What does "coffee bloom" refer to?

"Coffee bloom" refers specifically to the release of gases, particularly carbon dioxide, that occurs when hot water first contacts coffee grounds. This process is most noticeable with freshly roasted coffee, as the beans still contain trapped gases from the roasting process. When the hot water hits the grounds, it causes these gases to escape, resulting in a visible expansion or "bloom" of the coffee grounds. This step is crucial in brewing as it allows for optimal extraction of flavors and aromas during the brewing process.

Additionally, the freshness of the coffee plays a key role in the blooming effect; older coffee may not exhibit as significant of a bloom due to the degassing process that diminishes over time. Understanding coffee bloom is essential for achieving the best flavor profile in brewed coffee, making it an important concept for coffee enthusiasts and baristas alike.