Bloom occurs once a freshly roasted coffee is brewed. This is when carbon dioxide and coffee grounds bubble up and it is known to enhance flavors. It is advised to let your cup bloom for 30 seconds, or depending on how recently it was roasted.
Coffee blooming is the rapid release of gas that is produced upon contact of hot water and coffee grounds, and coffee lovers swear by it! In essence, apply heat to any organic substance and carbon dioxide will be released.
Now don’t confuse coffee blooming with degassing. Degassing is the little by little release of gas after roasting. This is where the roasting timing comes into play. If you are brewing your cup within ten days since the roasting process, you’d want to bloom it to ensure that carbon dioxide is eliminated. Otherwise, your coffee would most likely have a significantly reduced carbon dioxide content.
The blooming process causes the coffee grounds to puff up once they come in contact with hot water. This is the out-gassing where your carbon dioxide is released at a faster rate. By blooming, we make space for water, thus, it enhances the flavors.
Now what if you don’t see any traces of bloom? That’s perfectly okay! It only means that your coffee has already degassed, however, this is also a signal that your coffee is not as fresh anymore.
Factors that affects the bloom
Freshly roasted and ground coffee
It takes around a couple of weeks for the degassing to finish, but most of the gasses will be gone by the first week. These gasses also carry a lot of flavors which is why it is best to brew them as early as possible without forgetting to bloom to maximize your coffee experience. Another thing is that it’s best to grind right before you brew because grinding beans results in faster gas reduction, thus, we want to avoid loss of flavors!
Coffee bean storage
As a rule of thumb, make sure to store your beans in airtight containers! This is to not allow gases to escape and to not allow gases from the surrounding to enter. Using airtight containers prevents your beans from going state prematurely.
Temperature during storage
Hotter surrounding temperature releases more gas.
Humidity during storage
When it comes to humidity, you’d want to find your safe spot. Storing it in a dry environment allows more gas to escape while extreme humidity encourages the growth of fungus and molds.
Dark and oily Italian roasts out-gasses a lot less than the same coffee roasted at the “Full City” level.
The harder the beans, the denser they will be allowing more gas to go through.
How to bloom?
It’s quite simple. The basic way to do it is pour in hot water to the coffee grounds and leave them damp for one to two minutes before extracting. But, through the years, there are now other techniques to do so based on the brewing method.
Add 40-80g of very hot, but not boiling, water over the grounds in a way that you pour them strategically in a circular motion. Start from the outer wall inward. The goal is to have the grounds uniformly and evenly soaked without being dripping wet. Let this sit for a minute.
French press blooming
Ensure that you have a coarse grind. Slowly pour a little amount of hot water over the grounds and watch them foam on top of the water in the press-pot. This is the blooming process. Let it bloom for about 15-20 seconds before stirring.
Blooming a French press coffee remains to be controversial. Some coffee aficionados find it worth doing, while others question the need to do it. But as always, it depends on preference! We suggest you try to do it both ways and see which method you like better. Whether it’s a bloomed French press or not, it’s totally up to you!
Automatic drip coffee blooming
Place your filter in the basket. A great tip is to utilize high quality filters to ensure that badly flavored oils don’t make it to your brew. We personally recommend Melitta or Filtropa filters. Next, put in freshly roasted and ground beans and add hot water. Make sure that you pour in just enough to soak the grounds without pouring through. Let the grinds settle for about 45-90 seconds. After that, operate your automatic coffee and brew.
Cold brew blooming
For cold brews, simply add coarsely ground coffee into the vessel and add hot water like you normally would. Let that sit for 30-45 seconds. After which, simply pour in cold water and cold brew as usual.
Manual espresso brewing
Blooming isn’t actually the best term to use with espresso machines. Rather, we use the term “pre-infusion.” The goal is to wet the grounds fully to pave the way for better extraction. This process also aids in having coffee swell up which induces better resistance to pressing hot water through the filter. This simple process allows richer flavors to surface.
To pre-infuse using a lever espresso machine, latch the lever into position by lifting it and wait for 15 seconds for the filter basket to be filled with hot water. Pull the lever halfway for 15 seconds to allow a tiny amount of espresso to flow. After that, lift the lever again but this time for 30 seconds.
Which brewing method benefits more from blooming?
First and foremost, blooming with any brewing method does not have any negative effects on your coffee. But, immersion brewing methods such as espressos and percolators only have limited benefits from the process.
How to count the grams of water in the bloom?
You have to simply count it as part of the total weight. Thus, following the SCAA’s “Golden Ratio” of 55g liter, pour 66g of water for the bloom in a 33g coffee brewed using the 600ml Hario V60 brew. That’s double the weight of the coffee. If you would follow the Hario recommendation of adding 200g of water per 30 seconds, ensure to stop at 600g off total weight. Again, try to do it both ways for you to identify which method works best for you!
And that’s about it!
Blooming can make a huge difference in your cup of Joe only if you do it the right way and ensure that it works well with your preferred brewing method. Have fun blooming!