To bloom, or not to bloom?

To bloom, or not to bloom? That is, for us coffee nerds anyway, the question.

Blooming is one of the pieces of received wisdom that we’re all told to do – like rinsing paper filters or spinning tampers – but never stop to think about. What does it actually achieve? Is there a better way of doing it? Will the coffee gods hate me if I don’t do it?

Blooming is the very first part of a pour-over, where you add a small amount of water to the dry coffee grounds and let them soak for around 30 seconds. Some people like to give them a stir, some like to swirl, and some just let them hang out together.

The Release of CO2

There are two goals behind blooming. First, to get all the coffee wet as quickly as possible, making sure there are no dry clumps that might lead to an uneven extraction where some of the coffee isn’t in on the fun. Second, to release CO2 from the coffee. Roasting coffee produces CO2 which gets trapped in the beans, and it needs to be released to properly brew the coffee. This release is what causes the bubbles when you hit the coffee with water – the bloom.

But is it really necessary? Some brewers, especially those making pour-overs in cafés, have grown frustrated with the bloom: 30 seconds is a long time in coffee! This has led some to experiment with so-called “no-bloom” methods. Most (like this one) involve making a small well in the dry coffee bed, which allows the grounds to saturate faster as you pour outwards from the centre. This is necessary in place of the swirl or stir normally used during a bloom. This initial pour is then simply continued until all the water has been added.

This definitely makes for a faster brew, and a simpler method: one pour, done in under two minutes. But there are a few challenges posed. First, without a bloom, it takes a little longer for all the coffee to become saturated, which can lead to an uneven extraction and a less balanced cup.

Second, most no-bloomers will use a lower brew temperature to moderate the release of CO2, as hotter water releases CO2 faster, which in a no-bloom brew can over agitate the coffee and lead to over extraction and bitterness. This can be a problem, especially with lighter-roasted, harder-to-extract coffees, which can end up under-extracted and sour at lower temperatures.

So, while no-bloom methods might make for a faster, simpler recipe, completed in one pour, they introduce new challenges that you need to be aware of. They are not a silver bullet that solves all problems, they’re just a different approach. Depending on your priorities, their strengths and weaknesses might suit you better. Try it out for yourself!

Want to learn more? Find out more about blooming, and everything else you could ever dream of knowing about brewing filter coffee, by booking a training session with Joel, our trainer.


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