What Is Coffee Bloom and Why Does It Matter?

Last Updated:

Coffee blooming

Image Credit By: Manseok, pixabay

Assuming your group of friends includes a person who loves coffee, perhaps you’ve heard the term, “coffee blooming.” It’s a lovely phrase, really, and once you understand what it is, you’ll see that its physical action is as beautiful as its name. It will also help you brew better cups of coffee, as coffee bloom is a vital part of the brewing process. Almost a reverse crema, the bloom is what gives coffee life.

If you thirst for coffee knowledge is as strong as ours, then let’s go learn about coffee bloom!

What Is Coffee Bloom?

The bloom of coffee is when all of the gases that have been trapped inside the coffee bean start leaking out. This process begins when hot water is introduced to the grind. Then the bean absorbs and expands and at the same time, pushes out all the CO2 trapped inside. Where does the CO2 come from? It happens during the roasting process. Dark roasts, for example, have more of a bloom, as they are roasted for longer and more CO2 gets trapped inside.

Why Does It Matter?

This is how we can tell how fresh a bean is or how freshly roasted it is. The reason it matters is that there is a bunch of flavor in those gases, as well as aromatics. The less gas in your coffee, the staler it will taste. This makes sense because if a coffee doesn’t bloom, it’s probably old. Of course, coffee can go stale in many ways, and there are multiple factors to consider when discussing coffee bloom.

Why Does Coffee Go Stale?

Coffee goes stale for the same reason that coffee blooms, it just takes longer. The moment coffee beans are pulled out of a roaster, they start losing the gas built up inside them. Therefore, you can tell how fresh your coffee is by how intense the bloom is. With certain extraction methods, you actually want to wait for the coffee to lose some of its gaseous nature, as an excessive amount can lead to a drink tasting ripe.

You will also probably not get much or any bloom out of pre-ground coffee. The gas inside a coffee bean normally sticks around for 10 days to two weeks, but once the coffee is ground, it begins rapidly escaping. This is also why the coffee world strongly urges people to invest in a grinder and buy their coffee whole bean.

Pour over coffee bloom

Best Way to Bloom

The brewing method that showcases a bloom most easily is a Chemex. It is the first thing that happens when you swirl the hot water over the grinds. This process is even more neat to watch when you have a better understanding of what is going on. As the coffee expands, you can see the flavor going into the pot and smell it while it’s happening.

What Variables Affect Coffee Bloom?

All sorts of things affect the bloom of a coffee. Many do so while it’s just sitting around. So, what are the variables?

  • Temperature: If beans are in a hot area, they will lose gas quickly, which is why it is recommended to store whole bean coffee in a cool place. The refrigerator seems ideal, but coffee is very sponge-like and will absorb the flavor and smell of whatever else is in the refrigerator.
  • Roast: The darker the roast, the more gaseous it is. Although, interestingly enough, the darker the roast, the slower that the gas escapes, meaning there is less of a fascinating bloom with darker coffees.
  • Bean hardness: If a bean is really hard, gas will have a difficult time escaping.
  • Humidity: In really dry areas, beans de-gas very quickly. There are items on the market that help you keep your beans humidified.

Add coffee bloom to the list of things you now know about coffee! You can use it as a centerpiece for conversation, or maybe you will wind up being the friend who loves coffee! Either way, this is a powerful piece of information to have. You can talk to your friends through a brewing process and be able to spot stale coffee the moment water touches it. Happy brewing!

Other posts we recently published: