Why is Blooming Necessary in Pour-Over Coffee? Why Does the Water for Degassing Use Double the Amount of Coffee? What Determines Coffee Concentration?

The Blooming Question: Should You Discard the Liquid Dripped During the Bloom?

Today FrontStreet Coffee dug up an intriguing old topic worth revisiting: "Does pour-over coffee taste better if you discard the coffee liquid that drips out during the blooming stage?" The reasoning behind the question is just as interesting, so let's unpack it.

As we know, blooming wets the grounds and releases the carbon dioxide that hinders extraction, setting up the best possible environment for the hot water that follows to pull flavor compounds from the grounds. That means we want to reserve as much hot water as possible for the main extraction, letting it do the heavy lifting — so the bloom itself should use as little water as we can get away with.

Happily, dry grounds need to absorb hot water to reach saturation, and experimental data shows they absorb roughly twice their weight. Hence the standard: bloom water equals twice the coffee dose. That saturates the grounds for the bloom without "wasting" excess water. But not all of it gets absorbed. Some water is unevenly distributed and never reaches every particle, and pour rate plus grind size directly affect how fast water penetrates — indirectly affecting absorption. So some of the bloom water inevitably drains through into the server below.

Which led some people to speculate: since that water exists only to wet the grounds and clear extraction obstacles, isn't its extraction environment weaker than the water poured later? Wouldn't the drained liquid be lower in concentration — and shouldn't we discard it to keep it from diluting the whole cup?

Should the Blooming Liquid Be Removed?

Notice how similar this sounds to cut-off (flow separation)? Cut-off means truncating the final portion of a brew because it may carry excessive undesirable flavors, keeping negative tastes out of the cup. Removing the bloom liquid, by contrast, is about avoiding dilution. Do both to one brew, and you get the classic "chop the head and tail" approach.

FrontStreet Coffee has covered cut-off before — see "Is Flow Separation Necessary in Pour-Over Coffee?" The gist: it's legitimate, but shouldn't be applied indiscriminately. As for "removing the head" — discarding the liquid that drains during the bloom (long name; let's just call it "blooming liquid") — FrontStreet Coffee can state definitively: don't. Why? Let's brew a cup and show you.

For this test, FrontStreet Coffee used Panama Green Label Geisha. Its medium-light roast absorbs water at a moderate pace, so some liquid inevitably drains during the bloom — and its prominent flavors make the with/without comparison easy to read. The parameters: 15g of coffee; 1:15 ratio; grind at setting 10 on the EK43 (fine-sugar texture, 80% pass-through on a #20 sieve); 92°C water; V60 dripper; three-stage pour.

We start with the bloom: twice the coffee's weight in water (30ml) for 30 seconds. FrontStreet Coffee finished pouring the 30ml in 8 seconds, and by the 10-second mark liquid was already draining.

By 24 seconds the dripping stopped. At that point we poured the liquid in the server into a small cup and set it aside.

Then we tared the scale and restarted the extraction (easier math that way). Second stage: 130ml of water, small flow in wide circles. When the water level nearly exposed the grounds, we poured the remaining 65ml, larger flow in tight circles. Once the extraction finished, the comparison could begin!

Frankly, the photo below already gives the answer away — the blooming liquid is very dark, a sign of high concentration. But for rigor, we ran the numbers anyway.

Comparison Results

Measured with a coffee refractometer, the brew without the blooming liquid came in at 1.25% concentration. Flavor-wise: subtle jasmine florals, high honeydew-melon sweetness, light berry acidity, and a long aftertaste.

Next, we stirred the blooming liquid (15ml) back into the coffee.

The re-measured concentration: 1.38%. The reintegrated Green Label Geisha showed brighter citrus acidity, higher overall sweetness, more pronounced flavors, and a fuller mouthfeel.

Conclusion

The takeaway: the liquid that drains during blooming matters a lot! Coffee's flavor compounds are finite and dwindle as extraction proceeds. Even if the bloom's extraction environment isn't as good as the main pour's, the grounds at that moment hold their richest, most abundant compounds — so even under imperfect conditions, that first water extracts a great deal, making this small amount of liquid extremely concentrated (high flavor content per unit).

Discard it, and you lose rich flavor and reduce the body of the cup. A counterproductive move — sacrificing both flavor and mouthfeel — and not worth attempting.

FrontStreet Coffee Recommendation

The star of this experiment, FrontStreet Coffee's Panama Green Label Geisha, is well worth seeking out for its bright citrus, jasmine, and honeyed sweetness in a medium-light roast. If Panama Geisha appeals to you, the entry-level FrontStreet Boquete washed Geisha offers the same pure Geisha character — orange blossom and honey notes — at a far friendlier price, and responds beautifully to a proper three-stage pour with a well-executed bloom.

For everyday brewing, FrontStreet Coffee's washed Yirgacheffe Guodingding brings the same floral-citrus elegance in a more affordable package: white jasmine, citrus, orange, and green tea, perfect for practicing your bloom-and-pour technique.