If you’re new to the world of coffee brewing, yet are serious about learning how to brew the perfect cup of joe, it’s important that you know and understand the concept behind the term ‘coffee bloom’. You must have overheard your friends or the barista at the coffeehouse mention coffee bloom in a conversation, and wondered why it’s relevant.
This article will guide you through the science behind coffee bloom, and why it is important for you to understand this vital phenomenon in coffee brewing.
All About Coffee Bloom
Coffee bloom refers to the process wherein all the trapped gases inside the coffee grounds start leaking out or escaping. The majority of these gases constitute of carbon dioxide or CO2. The blooming process gets initiated as soon as the hot water first comes in contact with the coffee grounds – the ground coffee beans absorb the water and expand at the same time, releasing the gases trapped inside.
Wondering how to know if the coffee you just brewed is ‘blooming’? When blooming, the coffee undergoes almost the reverse process as that of crema formation, wherein the coffee grounds puff up and bubble quickly when exposed to hot water. You will notice a turbulence effect or rapid out-gassing when the trapped gases emerge out of the coffee grounds, almost pushing the water away due to the pressure.
The ideal thing to do here is to wait for the blooming to get over, so that the water can then enter the coffee grounds properly to release the volatile compounds and coffee oils that render the resulting cup of coffee that perfect taste and aroma.
What Causes Coffee Bloom?
The blooming of coffee pertains to the release of carbon dioxide trapped inside the beans. Where did this CO2 come from, in the first place? This gas, along with other volatile compounds, is formed during roasting process of coffee beans. As the beans get subjected to heating during the roasting process, CO2 gas gets trapped inside the beans. Once the roasting process is over, these gases start to slowly discharge over time in a method known as degassing.
Experts estimate that these gases formed during roasting are retained in the coffee beans for a time-frame of up to 10 days, wherein the expulsion happens little by little over time. However once the beans are ground, these gases are expelled at a relatively faster rate, and when exposed to hot water the grounds immediately purge themselves of the gases, thus creating the ‘bloom’.
Fresh Roasted vs Ground Coffee – How Does That Make a Difference?
Once the beans are roasted, the loss of inherently trapped CO2 and other gases takes place gradually over the course of next few weeks, but the major portion of gases are discharged in the first week itself. It is best to consume the beans within 10 days of roasting if you want your coffee to bloom just right, as well as taste wonderful.
The volatile compounds released inside the coffee beans during the roasting process are also responsible for the great taste and aroma that we all love in our freshly-brewed cuppa, and thus it is in our best interest to keep these gases intact inside the beans until we get to the brewing process.
Once the roast beans are ground, the greater surface area of the coffee grounds enables the escape of trapped gases and compounds at a faster rate. This is why coffee-purists and reputed coffeehouses prefer not to pre-grind the roast beans, and instead proceed to freshly grind the roasted beans right before brewing.
5 factors that affect coffee bloom
- Packaging – If you purchase fresh-ground coffee from a roaster, opt for vacuum packaging that contains a one-way pressure relief valve, which helps the released gases exit the package but also prevents outside air from entering in, thus creating a vacuum that discourages further release of gases.
- Storage – Experts believe that storing the roasted beans inside an airtight container also serves to keep the flavor and aroma intact by discouraging a faster discharge of gases through the creation of a vacuum effect.
- Temperature & humidity – Higher temperatures make it easier for the gases to release, while cooler temperatures help retain the flavor for longer duration. Similarly, drier climates fasten the process of gas discharge from the beans, whereas excessive humidity may promote fungus or mold growth. It is essential that the fresh roast beans are stored in a happy medium with moderate temperature and humidity levels, preferably in shade.
- Roasting levels – Roast levels have a major impact on the blooming process. Dark roast authentic-quality beans undergo very little degassing and retain the essential aromatics for a longer period. Medium roast allows a smoother taste but also hastens the degassing process, whereas light roast coffee beans tend to discharge the gases fastest.
- Exposure to water during brewing – Regardless of the method you use for brewing, if the coffee grounds aren’t properly exposed to hot water, you will get a weak extract devoid of the right flavor and kick.
How to make coffee bloom
Blooming of coffee doesn’t require any additional equipment. Regardless of the methods you use – be it French press, pour over, or automatic drip coffee maker – all you need to do is pour a little quantity of water to dampen the grounds and wait for 30-50 seconds to allow them to bubble up and degass. Continue with the brewing procedure as usual once the blooming is over.
Why is blooming of coffee so important?
Allowing the gases to escape through blooming will improve the coffee flavor in the following ways:
- CO2 gas is fizzy and sour-tasting. Not allowing the coffee grounds to bloom properly can render a sour or metallic after-taste to the finished coffee.
- Entrapped gases inside the grounds can prevent the hot water from extracting the aromatic oils to a full extent. Blooming of coffee will allow CO2 to escape entirely, thus permitting the fullest extraction of coffee oils, resulting in a cuppa that tastes divine.
Coffee bloom isn’t just a fancy term that coffee-lovers use, and is much more than just an interesting chemical reaction – it’s a phenomenon that will largely determine the resulting aroma and flavor of the cup of coffee you just brewed.