Why Blooming Fails | The Purpose of Coffee Blooming | Why Do You Need to Bloom Coffee?

When it comes to pour-over coffee, we know we need to let the coffee grounds bloom first, but many people fail at this step. What exactly is blooming for? And why do our own blooming attempts fail? Today, FrontStreet Coffee will analyze the reasons for blooming failure with everyone.

The so-called blooming is a preliminary step of using a small amount of hot water to wet the coffee grounds before formally brewing coffee. After roasting, coffee beans gradually release carbon dioxide through small pores on the surface. This process is called "bean awakening" or maturation, with different emission rates depending on the degree of roast. As time passes, the emission slows down. Blooming captures the moment when hot water contacts the powder, allowing gases to be rapidly released.

This seemingly simple action greatly affects the final product. After being ground into coffee powder, the surface area in contact with the outside world increases dramatically, and gases begin to escape. These gases form a barrier layer between the hot water and the powder, preventing effective extraction. Moreover, when carbon dioxide dissolves in water, it creates a sour taste, resulting in an unpleasant mouthfeel. Wetting causes the temperature to rise, gases to be expelled upward, making the surface of the coffee grounds bulge, and the entire mass expands. Some say the degree of bulging on the coffee grounds represents the freshness of the coffee, but regardless of whether it forms and its size, the key is whether this action achieves its purpose.

Three Key Points of Blooming

Whether you can achieve good blooming effects can mainly be discussed in the following three aspects:

Water Amount

The control of water amount lies in how much the powder will absorb. Generally, the powder will absorb about twice its weight in water, meaning 1 gram of powder corresponds to 2 grams of water. This ratio allows the powder to be evenly wetted without excessive extraction liquid flowing out. Too much water will cause early extraction to begin, affecting the blooming's structural system; too little water will prevent the powder from being completely wetted. If there are still large bubbles emerging during extraction, it might be due to insufficient water - some parts weren't soaked, leading to uneven extraction and unbalanced taste. You can increase or decrease the water amount according to the situation.

Water Temperature

When brewing coffee, water temperature affects the extraction rate and consequently changes the taste over time. The water temperature for blooming is even more important for coffee quality than controlling the water temperature when starting the pour-over process, and it's also an important link throughout the entire process. Blooming is the beginning of contact between water and powder, and whether the temperature is appropriate is a crucial moment that affects the activation of the entire system.

Light-roasted, harder coffee beans release gas more slowly and require higher temperature water to accelerate gas emission. Generally, the water temperature is controlled around 90 degrees Celsius, similar to brewing. Although higher temperatures make aromas more obvious, there's also a risk of bringing out astringent flavors. Dark-roasted, softer coffee beans have higher activity themselves, and gases are easier to release, so the water temperature can be slightly below 90 degrees. Adjusting the water temperature according to the degree of roast and quality of the beans can make the entire brewing process smoother, steadily bringing out the coffee's aroma, taste, and body.

Time

The blooming time is calculated from the completion of water pouring, with times ranging from 20 seconds to about a minute being used by different people. It mainly depends on the formation of the "burger" (coffee bed) and whether gases are smoothly released to judge. 30 to 40 seconds is a more common time. Too long a blooming time will over-excite the coffee grounds, bringing out subsequent bitterness and astringency; too short will result in insufficient wetting, and during brewing, the flavors won't be able to manifest.

Common Blooming Problems

Through long-term observation and summarization, FrontStreet Coffee has found that many people mainly encounter the following problems when pouring water for blooming:

1. Uneven Water Pouring

This situation is more common for beginners and easily happens when not familiar with the pour-over kettle: the water stream is sometimes thin, sometimes thick, the circling isn't round, and the pouring is asymmetrical. The consequences are that areas with more water overflow and penetrate through the filter paper; areas with less water cannot completely wet the coffee grounds, greatly reducing the blooming effect. This ultimately leads to over-extraction in some areas and under-extraction in others during subsequent water pouring and extraction, resulting in messy flavors and easily appearing astringency.

2. Too Gentle Water Pouring

Overall, this situation should be quite rare, and even if it occurs, it's not very obvious. It mainly happens more when using a narrow-spout kettle:

① Due to nervousness or unfamiliarity, some people will be very careful when pouring water when facing some special (expensive) beans, worried that they might ruin a pot of good beans if they're not careful. Little do they know that the more careful and cautious they are, the more likely problems will occur. When you pour water particularly gently, or believe in the so-called "water spreading" theory, pouring without enough force to let water penetrate the surface powder layer, only wetting the surface, allowing water to penetrate deeper layers only through capillary action and gravity. At this time, the time for blooming water to seep from the surface layer to the bottom layer will be extended, and some water will spread from the surface and flow away through the edge ribs, reducing the actual amount of water received by the coffee grounds during blooming, naturally greatly reducing the blooming effect.

② The powder is too fine or too much. If the powder is too fine, the particles are tightly packed, and water penetration speed will be very slow, easily causing overflow. If there's too much powder, the powder layer will be thick. If the penetration force is insufficient, water will stay on the surface, and the result will still be water slipping away from the edges.

Everyone can make improvements based on the blooming knowledge shared by FrontStreet Coffee today~

Important Notice :

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