Why Is Coffee Blooming Necessary? What Is the Significance of the Bloom?

For professional coffee knowledge exchange and more coffee bean information, please follow the Coffee Workshop (WeChat official account: cafe_style)

Many people, including myself, learned early on when first encountering coffee that an essential step in brewing coffee is: blooming!

For pour-over coffee, the blooming process is crucial. Blooming is the starting point of the pour-over process, so the quality of this beginning has a significant impact on the taste of the final cup. Moreover, any poor results from the beginning cannot be compensated for through later adjustments.

The Purpose of Blooming

The purpose of blooming mainly involves two points:

First: Using hot water to prompt the carbon dioxide in the coffee grounds to be released as quickly as possible. This is because carbon dioxide hinders water molecules from entering the fiber structure of the coffee grounds and carrying out flavor compounds. Additionally, the release of carbon dioxide creates larger gaps in the coffee bed, causing water to flow unevenly through the grounds.

Second: Ensuring all coffee grounds come into contact with water, allowing them to fully absorb water and naturally expand. During the subsequent extraction phase, flavor compounds become more easily extracted.

Therefore, good blooming allows coffee grounds to release gas quickly, thoroughly, and uniformly while also enabling full and rapid contact with water, helping the grounds to be extracted evenly.

To achieve this, the amount of water used for blooming should be sufficient. During the blooming process, besides the coffee grounds absorbing about twice their weight in water, some water will also flow down the filter cup or through the coffee bed. Therefore, blooming should use approximately 2-3 times the weight of the coffee grounds in water to provide ample water for the grounds to absorb. Then, during blooming, you can use a small technique to achieve good results.

What to Pay Attention to During Blooming?

Just the Right Amount of Water

If too much water is used for blooming, causing a large amount of coffee liquid to drip down, the situation is that the falling water doesn't linger but directly carries away substances from the exterior of the coffee grounds. When the outer layer components of the coffee grounds are dissolved, the inner layer is still dry. As hot water penetrates into the inner layer of the coffee grounds, the bitter and astringent tastes from the outer layer also begin to dissolve. Coffee brewed this way will be both weak yet have over-extracted off-flavors.

If the blooming water amount is insufficient with no water dripping down, this means the coffee grounds haven't absorbed enough water, and some coffee hasn't released enough gas, which will result in under-extraction.

Don't Be Too Gentle With Water Pouring

When you pour water very gently, or believe in the so-called "water spreading" approach, pouring without enough force to let water penetrate the surface layer of grounds, only moistening the surface and allowing water to rely on capillary action and gravity to seep into deeper layers, the time for blooming water to penetrate from the surface to the bottom layer will be extended. Additionally, some water will spread from the surface and flow away through the edge ribs, reducing the actual amount of water the coffee grounds receive during blooming, naturally diminishing the blooming effect.

1. Increase the force of water pouring, which can be approached from both the water stream size and pouring height. After all, some narrow-spout kettles are truly only suitable for fine water flows - once the flow increases, the water column tends to tilt. In this case, raise the pouring height a bit and let gravitational acceleration provide sufficient penetrating power for you. Of course, be careful not to create splashing water.

2. Appropriately increase the amount and time of blooming. Since the penetrating force is insufficient, which reduces the actual blooming water amount and slows down the process, just add a bit more water and extend the blooming time.

But is the blooming step absolutely necessary when doing pour-over coffee? FrontStreet Coffee, using 8-day-roasted Yirgacheffe Worka as an example, will compare the impact of blooming versus not blooming on a cup of coffee!

In terms of flavor, the cup that included the blooming step tastes richer, with floral notes that are much more pronounced than the non-bloomed version, and also shows more complexity in layers. Meanwhile, this cup of Worka without the blooming step has some acidity and astringency, carrying grassy flavors, clearly showing signs of under-extraction.

However, this is merely the conclusion from my experiment this time. Perhaps some friends, even without performing the blooming step, happen to compensate for the under-extraction caused by lacking blooming through their pouring techniques. Techniques vary from person to person, and there's really nothing absolute in coffee brewing ~ This is precisely the charming aspect of pour-over coffee!

FrontStreet Coffee: A roastery in Guangzhou with a small shop but diverse bean varieties, where you can find various famous and lesser-known beans, while also providing online shop services. https://shop104210103.taobao.com

Important Notice :

前街咖啡 FrontStreet Coffee has moved to new addredd:

FrontStreet Coffee Address: 315,Donghua East Road,GuangZhou

Tel:020 38364473