What's the function of the coffee bloom?

[RSC]

Can anyone give me a reason or reasons for blooming as part of the brewing process, either with french press or pourover? Have you experimented with blooming or not blooming, or with different amounts of water or bloom time?

I almost always do a manual drip (pourover), but occasionally use a french press.

 

[Mick]

When coffee is roasted CO2 is created within the bean's structure.

Most flavors within the beans are water soluble and removed in the brew process.

The bloom process allows the fast release of CO2 gas so that the actual brewing process can take place with less interference

If you do not see bubbles in your grounds and see the coffee mass increase in volume from the released gas, your coffee is old/stale and the bloom time is not necessary.

 

[shave/brush]

When coffee is roasted CO2 is created within the bean's structure.

Most flavors within the beans are water soluble and removed in the brew process.

The bloom process allows the fast release of CO2 gas so that the actual brewing process can take place with less interference

If you do not see bubbles in your grounds and see the coffee mass increase in volume from the released gas, your coffee is old/stale and the bloom time is not necessary.

Sorry but I don't understand what this means. Would you explain a little more please?

 

[Mick]

Sorry but I don't understand what this means. Would you explain a little more please?

Green (unroasted) coffee contains approximately 12% moisture

When coffee is roasted much of this moisture is driven off by heat. What remains of the moisture in the roasted coffee is in the form of gas which is predominantly carbon di-oxide (CO2)

Went roasted coffee is ground the gases inside the cell structure are more easily released. CO2 is soluble in water which is why you see bubbles when adding water to coffee grounds (unless the coffee is stale then nothing happens).

Is this the part you don't understand?

.

 

[Andy77]

That was the part I didn’t understand. Excellent post!!

 

[RSC]

I buy locally roasted coffee, paying attention to the roast date, and grind while I'm waiting for the water to boil, so I get a pretty good bloom.

One thing that I was wondering about was whether I should be concerned about the amount of water that I use for the initial pour. I use quite a bit and some of the water drips through. If part of the function is to avoid getting too much carbon dioxide into the brewed coffee, maybe I should be using less water for the initial pour. It sounds however like the function is more just to get better extraction. I generally wait about 30 seconds before pouring the rest of the water.

 

[shave/brush]

Green (unroasted) coffee contains approximately 12% moisture

When coffee is roasted much of this moisture is driven off by heat. What remains of the moisture in the roasted coffee is in the form of gas which is predominantly carbon di-oxide (CO2)

Went roasted coffee is ground the gases inside the cell structure are more easily released. CO2 is soluble in water which is why you see bubbles when adding water to coffee grounds (unless the coffee is stale then nothing happens).

Is this the part you don't understand?
.

Yes, thanks for the explanation.

 

[StillShaving]

I buy locally roasted coffee, paying attention to the roast date, and grind while I'm waiting for the water to boil, so I get a pretty good bloom.

One thing that I was wondering about was whether I should be concerned about the amount of water that I use for the initial pour. I use quite a bit and some of the water drips through. If part of the function is to avoid getting too much carbon dioxide into the brewed coffee, maybe I should be using less water for the initial pour. It sounds however like the function is more just to get better extraction. I generally wait about 30 seconds before pouring the rest of the water.

I think using a little too much or too little water for the bloom is okay. Though I personally err on adding a little too much. I view the bloom stage as an attempt to remove one variable from the brewing process, to let the active coffee bed settle down before moving on to the main brewing step.