If you watched one of our recent videos on how to make coffee in the Hario V60 by Gabriel de Carvalho Dias from Carvalho Coffee, you would have heard him remark this about a coffee bloom:


“It’s so beautiful to see this..”

Here at The Roasters Pack, one of our goals is to make coffee as accessible as possible. We want to try and share what makes coffee so dang special to us that we decided to start this coffee subscription (& discovery) service. That sentence on how the bloom is “so beautiful to see” is so vague yet accurate for us that it deserves an explanation.

What the heck is a bloom and why should you care?

The bloom is the part of the coffee brewing process in which the gasses from the coffee are released as the water hits the grinds. It causes the grinds to grow & rise. The CO2 that is inside the bean is purged out and replaced with the water and begins the brewing/extraction process.

Which is the ideal time for the gasses to be released from the bean.

If you don’t see the bloom when you make your coffee it most likely means that the degassing has already occurred and with that the flavor compounds within the beans have deteriorated preemptively.  The flavors therefore won’t be as prominent in the beverage you’re about to drink… which is unfortunate.

Generally this will happen for two reasons:

  1. Your coffee isn't fresh or
  2. The packaging wasn't sealed to prevent oxidization

However, it’s important to note some coffees tend to bloom more than others, which is a result of the roasting differences – so the bloom isn't an exact measure of the freshness of coffee. Generally speaking, darker roasts will bloom more than others because of the additional CO2 created through the longer roasting process.

Regardless of that, the reason we (among other coffee producers) package the coffee in a valve bag is to prevent the oxidation and the deterioration of the delicious flavor compounds inside the bean. It’s the same reason why we recommend using freshly ground coffee as once it has been chopped up it begins oxidizing at a much faster rate than in the whole bean form.

The bloom is not only a fascinating chemical reaction, it’s also a relevant part of the brewing process as the time you allow the coffee to be in this bloom state can have a large impact on the aromas and flavors of the cup you brew. This portion of the brewing can hold the most acidic characteristics, so if you are finding your coffee is overly bitter or perhaps too sour it may be due to the bloom time length. Sounds complicated eh? So an ingenious iPhone app developer created this piece of software to help you keep track of bloom times.

For us, when we see that bloom – it's a sign of the delicious, delectable and divine drink that we start our day off with. With that, we know the coffee is fresh and that some of the most interesting characteristics of the bean are being extracted. Interestingly enough a definition of bloom from dictionary.com is “a flourishing, healthy condition; the time or period of greatest beauty” and it relates perfectly to this discussion.

Happy brewing folks!

April 20, 2014 — Suneal Pabari

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