Why your coffee "blooms" when you brew it
When you pour hot water over freshly ground coffee, you've probably noticed those bubbles and the sudden growth of the coffee. This is called "blooming" or pre-infusion. But what exactly is it and why does it happen?
During coffee roasting, the beans go through many reactions that transform their components (more information about coffee roasting).. In this process, carbon dioxide (CO2) is generated, which is trapped in the roasted beans. When we grind the coffee, this gas begins to be released, taking valuable aromas with it. Therefore, the fresher the coffee, the more intense its aroma will be when ground.
How pre-infusion improves your coffee
Carbon dioxide can become an obstacle during brewing. If trapped in the ground coffee, it prevents water from penetrating evenly, causing uneven extraction and an unbalanced flavor.
When pre-infusing, you pour a small amount of water and wait a few seconds before continuing. During this time, the gas escapes, leaving the coffee ready for a complete, balanced, and flavorful extraction. Skipping this step can mean losing much of the aromatic richness your coffee offers.
What influences a good pre-infusion
Not all coffees require the same pre-infusion time or strength. There are several key factors:
- Roast freshnessThe fresher the coffee, the more time you'll need (up to about 45 seconds). Older coffees usually require less time (about 20 seconds).
- Roasting levelLightly roasted coffees release gas slowly and require a longer pre-infusion.
- Grinding thickness: A coarse grind retains more CO2 and requires a longer pre-infusion than a fine grind.
If you're making filter coffee, a good pre-infusion is crucial due to its coarser grind. In espresso, however, using finer grinds and darker roasts releases the gas more quickly, making the pre-infusion less noticeable but just as important.
Pre-infusion reveals if your coffee is fresh
Observing how your coffee blooms can tell you a lot about its freshness. Freshly roasted coffee produces a lot of bubbles, clearly demonstrating its freshness. On the other hand, if you see little or no bloom, your coffee is likely old and has lost its aroma and flavor.
In professional coffee shops, many machines have automatic pre-infusion systems. Although not as visually striking as manual methods, they are still key to achieving balanced flavors.
How temperature influences pre-infusion
The way you store your coffee also affects how much CO2 it retains. Exposing roasted beans to heat or sunlight accelerates the loss of essential gases and aromas. Store it in a cool place away from direct light.
Additionally, the temperature of the water you use directly affects the rate at which CO2 is released. Warmer water will accelerate the release of the gas, while slightly cooler water will do so slowly.
Tips for a perfect pre-infusion
Ideally, you should let your coffee bloom for a few minutes. 30 seconds As a general rule, use a water-to-coffee ratio of between 1:2 and 1:3 for this initial phase. For example, for 15 grams of ground coffee, use between 30 and 45 ml of water. Then continue brewing according to your favorite recipe.
Take a good look at how your coffee blooms next time; this simple gesture will tell you if you're on your way to the perfect cup.
