The Principle and Purpose of Coffee Blooming: Pour-Over Coffee Brewing Guide for Beginners

Coffee tastes good - that's what FrontStreet Coffee says. Of course, first you need to brew it well, and only then can high-quality coffee be brewed deliciously! This involves many factors, and pour-over brewing technique is one of them. Although it may seem simple - just pouring water in circles - there are key points that must be noted. As the saying goes: laypeople watch for the spectacle, while experts understand the essence.

The Purpose of Blooming

The purpose of blooming during coffee preparation is to help coffee grounds release carbon dioxide smoothly. To achieve this goal, the water amount must be appropriate, and you need to gently let the water rest on the coffee grounds, allowing it to slowly seep into the grounds and force out the carbon dioxide, ensuring smooth extraction afterward.

For pour-over brewing methods, the amount of water for blooming is relatively easy to master. The blooming water amount should be just enough to wet the grounds layer, until you see drops beginning to fall from the lower edge of the grounds. However, this places high requirements on the pouring method - it must be gentle, stable, and quick, preferably without bubbles forming on the blooming grounds surface. Because if bubbles form, it indicates that local water volume is too high, causing water to flow directly through the grounds, resulting in uneven soaking of grounds.

At this point, the coffee grounds layer has been fully soaked, and water begins to seep into the grounds to squeeze out carbon dioxide. We can clearly see the grounds begin to swell, with carbon dioxide continuously releasing from inside. The best time for the second pour is when all carbon dioxide has been released and the coffee grounds begin to collapse downward. However, determining exactly when this moment occurs requires careful observation. If you can't observe this clearly yet, we suggest that fresher coffee beans require longer blooming time.

For example, freshly roasted beans that have rested overnight may need 45-50 seconds of blooming, beans after three days can be reduced to 30-35 seconds, while beans after a week only need about 20 seconds of blooming. If older beans cannot swell after pouring water, we recommend skipping blooming and proceeding directly to the second pour.

Similarly, for French press, electric drip, Aeropress, and other brewing methods, we also recommend adding a blooming process for fresher beans to achieve more efficient extraction. The blooming water amount and time can reference pour-over methods, but for French press, we suggest appropriately reducing the blooming water amount.

How Much Water for Blooming?

Since the purpose is to apply a small amount of hot water to release carbon dioxide, the water amount can be controlled at equal to the coffee grounds weight to 2 times that amount, or 10% of the total water volume. At FrontStreet Coffee, we typically use 15 grams of grounds with 30 grams of water for 30 seconds of blooming.

Should You Time Before or After Blooming?

People often ask us this question. Taking our most commonly used example at FrontStreet Coffee of brewing with 15 grams of grounds, we typically pour about 30 grams of water for a blooming time of 25-35 seconds.

For unconventional blooming pouring techniques, it's generally specified as pouring time + blooming time. In any case, the time spent pouring is not counted in the blooming time. Pouring is pouring, blooming is blooming - their times are calculated separately.

If you start timing after pouring is complete: 10 seconds of pouring + 30 seconds of blooming = 40 seconds, which would be 10 seconds longer than our default blooming.

If you start timing from the moment you begin pouring water: 10 seconds of pouring + 20 seconds of blooming = 30 seconds, which would be 10 seconds less than our default 30-second blooming because of those 10 seconds of pouring.

So the question is: how much does a 10-second difference in blooming time affect pour-over extraction?

Example: FrontStreet Coffee Yirgacheffe Gedeb

For better comparison, we kept all parameters consistent:

Filter: V60
Grounds amount: 15 grams
Water-to-coffee ratio: 1:15
Temperature: 92°C
Grind size: BG#6S

FrontStreet Coffee Brewing Method

First cup: Start timing first, then bloom 15 grams of grounds with 30 grams of water for 30 seconds. Pour in circles to 125 grams. When water level drops halfway, continue pouring to 225 grams. Extraction time: 2 minutes 10 seconds.

Second cup: After pouring 30 grams of water, bloom for 30 seconds. Pour in circles to 125 grams. When water level drops halfway, pour to 225 grams. Extraction time: 2 minutes.

Flavor Description

First cup: Initial notes of citrus and black tea, with floral aromas revealing cream, caramel, and almond undertones as temperature changes. Sweet aftertaste is prominent, with a clean and sweet mouthfeel.

Second cup: Initial black tea and citrus notes, with slight astringency in the mouthfeel. As temperature changes, it also reveals cream, caramel, and almond undertones. The aftertaste is less prominent but the mouthfeel is still clean.

Conclusion

Overall, as long as water temperature and grind are correct, and the blooming operation is error-free, slight deviations in blooming time (within 10 seconds) don't have as significant an impact on the overall pour-over result as one might imagine. In fact, if you weren't comparing two cups side by side, you might not even notice the difference.

Actually, the real purpose of FrontStreet Coffee conducting this experiment wasn't to make everyone obsess over 10 seconds of blooming time, but rather to encourage everyone to carefully observe the surface state of the grounds during blooming to determine when blooming should end. After all, different roast dates, water temperatures, and grind sizes all affect blooming effectiveness and duration. The 30-second blooming time suggestion from our team is only optimal for the peak flavor period - a few seconds of deviation before or after is acceptable.

Important Notice :

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