Thank you very much for Blooming
Blooming is essential for perfect extraction. But what exactly is this part of the coffee-making process all about? And why is it called that in the first place?
Preparation is essential before you can really get started. After all, making coffee isn’t just a simple matter of “water in, coffee out.” You can either just quickly satisfy your caffeine craving, or indulge in the pleasure of savoring the flavors slowly and mindfully. For the latter—to allow the complex aromatic notes to fully unfold—the ground coffee must first be moistened. “Blooming” refers to this process of moistening the ground beans.
When brewing filter coffee, start by pouring just a small amount of hot water evenly over the ground coffee in the filter. Use about twice as much water as ground coffee: if you’ve measured out 20 g of coffee, use 40 ml for blooming. The water is absorbed by the coffee and triggers several chemical processes that ensure the subsequent extraction of the coffee proceeds more evenly, thereby intensifying the flavor. Depending on when your coffee was roasted, you’ll notice a greater or lesser formation of bubbles. The ground coffee swells slightly, expands, and seems to unfold. Because this process visually resembles the blooming of plants, it’s called “blooming.”
These bubbles are caused by escaping CO2, as the coffee degasses when the flour is moistened. Depending on the roast level and roast date, the blooming effect is more or less pronounced. During roasting, lipids are released and oxidize upon direct contact with oxygen. A light-roasted coffee releases fewer lipids than a dark-roasted coffee. The former takes longer to degas and releases fewer gases. If the blooming is particularly pronounced, the coffee is still very fresh and has barely degassed. Extraction is difficult because the coffee still contains too many gases. If only a few bubbles form during blooming, the coffee has already degassed significantly. In both cases, the “sweet spot” has not been reached. Coffee that was roasted only recently cannot yet develop its full aroma, while coffee roasted a long time ago has already lost too much of its aroma and may taste like wood or paper. Therefore, it’s best to wait two weeks after the specified roast date before brewing it.
Allowing the CO2 to escape during blooming not only ensures even extraction but also intensifies the coffee’s flavor. Wait about half a minute before you begin the actual brewing process. The aromas come through more strongly, and the cup tastes neither bland nor sour. We conducted a direct comparison by brewing the same coffee—roasted two weeks ago—once with blooming and once without, using a V60 pour-over filter. When brewed without blooming, the coffee ran through faster and tasted flatter, while the version brewed with blooming was characterized by a fuller body and more pronounced acidic notes. Feel free to try this test yourself at home.
Blooming doesn’t just occur when brewing filter coffee, but also when preparing (good) espresso—though here it’s called “pre-infusion.” The process differs, but the principle is the same: Pre-infusion ensures a more even, higher extraction by moistening the grounds and allowing them to swell. Channeling should be prevented. Machines with an E61 brew group drip tap water onto the grounds before pressure builds up. Many rotary pump machines, on the other hand, slow down the water flow, so the pressure for the extraction process builds up only gradually. We’ve summarized the functions and characteristics of brew groups for you here. If your machine doesn’t have this capability, you can promote simultaneous extraction by tamping.
So it’s definitely worth taking the time and having the patience to brew filter coffee. If you want to treat yourself or your partner to a sensual experience and enhance the enjoyment, there’s no getting around the blooming process. Watch as the grounds unfurl like a bud after being gently teased by the water. Take a deep breath of the invigorating aroma and feel your whole body relax as the floral notes melt away your tension. Enjoy it.
