What is the coffee bloom?

Coffee bloom is the bubbling and expansion that may occur when hot water first contacts ground coffee. It is caused primarily by carbon dioxide created during roasting and retained within the coffee beans.

The amount of visible bloom can vary depending on the coffee’s roast level, freshness, grind size, and storage. Fresher coffee often produces a more noticeable bloom, but a small bloom does not necessarily mean the coffee is stale or poor quality.

During the brew cycle, your Moccamaster’s pulsing water flow wets the coffee grounds and allows the trapped gas to escape. This is normal and requires no additional action. Keep the brew-basket lid in place while the brewer is operating.