If you’ve read around our pages, we’ve mentioned bloom pour a few or more times. We may not have mentioned the exact, and somewhat elegant, expression. But we have referred to it several times. That’s what you do when you pour a little water over your coffee and then let it “bloom” for a few seconds.

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Bloom pour - ØNSK Kaffe

What is bloom pour?

Bloom pour is the process where you pour a little water over your ground coffee beans in e.g. your piston pot, your Chemex or your Hario, then let the coffee “bloom” for 30-40 seconds before continuing to brew. It allows the coffee to grow and develop, making a tasteful difference to your cup results.

Of course, there’s also a slightly more technical reason to bloom your coffee. Let us try to explain a little more:

Blooming is also a term for the off-gassing of coffee. When coffee beans are roasted, carbon dioxide is produced in the beans. That’s why you can see your coffee bubbling and fizzing when you pour boiling water over it. It is carbon dioxide that escapes from the coffee. It doesn’t matter if you brew instant coffee, AeroPress or pour-over coffee in e.g. a Chemex. Too much carbon dioxide can give your coffee a sour and not very pleasant taste, which is also why we “bloom” the coffee – to give the carbon dioxide time to release before we brew further.

Carbon dioxide also has the effect of actually preventing the water from coming into proper contact with the coffee beans and absorbing all the flavours therein. So when we let carbon dioxide out of the coffee by doing a “bloom pour”, we give the coffee the best conditions to grow tasty and ready to sip.

A blooming tip: Usually, a bloom pour is said to be about x2 of the coffee’s weight. So 50g coffee = 100g bloom pour. However, you can adjust the taste a little by controlling the size of the bloom pour. If you make a smaller bloom pour than double the coffee, the coffee will be sweeter, while if you make a larger bloom pour than x2, the coffee will be more acidic and fresh.

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