The Purpose of Coffee Bloom, The Role of Coffee Bloom, How to Adjust If Coffee Has Astringency?

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The Importance of Blooming in Coffee Brewing

In the brewing process, there is a crucial yet often overlooked step: blooming!

Understanding Astringency in Coffee

Generally, astringency mostly comes from the later stages of brewing, occurring when extraction time is too long. However, blooming can still be a source of astringency, and this type of astringency can be felt from the first sip through swallowing, making your flavor defects overwhelmingly apparent. It's difficult to mask with additional water or by reducing overall extraction time, which can indeed be frustrating.

The Purpose of Blooming

1. To ensure most coffee grounds absorb water and expel large amounts of air, creating a saturated state among the coffee grounds and enhancing extraction efficiency.

2. If water addition exceeds the absorption limit of the coffee grounds, subsequent water addition will push out the water initially absorbed into the coffee grounds.

What is the Water Absorption Limit of Coffee Grounds?

Different roast levels and grind sizes will all have variations. Additionally, during blooming, the outermost layer of grounds typically doesn't receive too much water, and factors such as water application method, water softness, and filter cup shape affecting ground distribution will all have an impact. Therefore, using a 1:2 bloom water ratio generally accommodates most situations better.

The second point mentions water exceeding the absorption capacity of coffee grounds, causing the phenomenon of initial water being pushed out. However, if you experience dripping due to the force from your pour-over kettle, coarser grind size, or excessive gaps between dry coffee grounds, even if water passes through the ground layer and drips out, the coffee grounds have still absorbed sufficient water, still achieving the purpose of blooming. It can even be considered necessary. In this case, even dripping won't cause blooming failure.

Optimal Blooming Techniques

1. When bloom water addition is within the 1:2 absorption limit, you can freely experiment with various water application methods.

For example: from inside to outside, from outside to inside, lingering longer in the center, rapid circular movements, slow circular movements, small amounts without circular movement—various techniques. Combine these with observation of blooming phenomena to find the method that achieves better degassing conditions. Don't worry about adding too much water; the ground layer has sufficient capacity to absorb it.

2. If dripping occurs during water addition, it must be accompanied by observation.

If dripping is caused by the ground layer not yet absorbing water and having larger pores, it might be due to too rapid water application or too much water at a single point. Simply adjusting the force of water application or the position of water application can improve this. Even if the drip amount isn't significant, you don't need to improve it, viewing it as a necessary process to achieve blooming. However, if dripping is caused by the ground layer already exceeding its absorption limit, it represents that within the 1:2 water addition (which should be a reasonable amount), the water absorption condition of the coffee grounds is uneven—some grounds absorbed too much water while others absorbed insufficient water. This will cause uneven degassing and affect the flow rate of subsequent water additions.

A typical observation point is: when adding water after blooming ends, the flow rate suddenly becomes fast and slow. Or if there are abnormally large bubbles rising around the ground layer, both indicate uneven water absorption by the ground layer, and you should return to reconsider the blooming process.

Blooming Time for Different Roast Levels

Furthermore, blooming time varies according to different beans. For example, dark-roasted beans have more vigorous degassing, so blooming for about 25 seconds is generally sufficient. Light-roasted beans can bloom for 30 seconds without concern! Taking FrontStreet Coffee's Golden Mandheling as an example, after blooming for about 25 seconds, you can observe the blooming surface change from moist to matte, which indicates that the blooming has ended.

FrontStreet Coffee: A roastery in Guangzhou with a small storefront 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