What's the Difference Between Bean Aging and Blooming? How Should You Brew Coffee Beans from Different Roast Dates?

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When we get a bag of coffee beans, we're always eager to tear it open and quickly brew a cup to taste what it's like! But have you ever thought that coffee beans aren't necessarily better the fresher they are? Roasted coffee needs to be rested for a period of time, which is what we commonly call "bean resting."

What is Bean Resting?

Coffee beans are like living things. As humans inhale oxygen, causing cellular oxidation, it's also a process of aging. Freshly roasted coffee is still too tender and hasn't reached its most mature stage. Just like people, it takes time to become more mature. Coffee beans need some time too. Simply put, bean resting is a "gas release" process, also commonly known as "blooming" or "maturing."

Because coffee beans that have just undergone intense roasting contain about 2% carbon dioxide by weight, and these large amounts of carbon dioxide are released depending on storage environment, equipment, or methods, causing the pressure inside the packaging to exceed atmospheric pressure. This pressure helps the fusion of aromatic substances and oils, allowing all aromatic substances inside the coffee beans to reach a state where they can be easily extracted.

If you look closely at the coffee bean packaging bag, you'll see a one-way exhaust valve. This is to release excess carbon dioxide, thereby preventing the packaging bag from being burst by carbon dioxide pressure.

The complete degassing process of whole coffee beans definitely takes much longer than the degassing process of ground coffee powder. Meanwhile, the degassing phenomenon of coffee beans also shortens their lifespan. During the early degassing process, air replaces the escaping carbon dioxide at approximately a 1:1 ratio. Since air contains about 21% oxygen, the absorption of air quickly causes the coffee to oxidize. As the coffee continues to degas, the internal pressure of the coffee beans decreases, and the degassing speed begins to slow down. Over time, a 12-ounce bag of roasted beans can release more than half a cubic foot of carbon dioxide.

What's the Difference Between Bean Resting and Blooming?

Although both are methods for letting coffee beans degas, there are differences. Unlike bean resting, which involves keeping the beans in a bag with a one-way exhaust valve, blooming involves directly exposing freshly roasted coffee beans to air for 12-24 hours to artificially accelerate the coffee's degassing.

How Does FrontStreet Coffee Suggest Brewing Coffee of Different Ages?

Coffee that is one day post-roast:

Taking Yemen Mocha as an example, we would use a higher water temperature than usual for extraction.

Grind size: BG 5R (Chinese standard 20-mesh sieve pass rate 64%) / 90°C / 1:15 / (timing from the start of bloom) 2'02"

Flavor notes: Gentle grape acidity, chocolate sweet aroma, special spice notes.

Coffee that is seven days post-roast, at peak flavor:

Taking Kenya Asali as an example, FrontStreet Coffee typically uses BG grind size 5M (Chinese standard 20-mesh sieve pass rate 60%) / 91°C / 1:15 / (timing from the start of bloom) 2'10"

Flavor notes: Cherry tomato, blackcurrant, honey.

Coffee that is two months post-roast, no longer fresh:

Taking Hacienda La Esmeralda Geisha Green Label as an example, beans that have been stored for a long time are very prone to over-extraction, so FrontStreet Coffee chooses a coarser grind than usual: BG grind size 6M (Chinese standard 20-mesh sieve pass rate 47%), with water temperature at 89°C.

Brewing technique:

1. Coarse grind: Since the volatile aromatic compounds in the coffee have basically been lost, fine grinding would more easily bring out bitterness during extraction. Choosing a coarser grind size can effectively avoid over-extraction.
2. Shortened bloom time: The carbon dioxide in the coffee has also been completely lost, so there won't be a "burger" effect. Water easily penetrates every coffee particle, so there's no need for long bloom times to release gas; otherwise, it would cause over-blooming and over-extraction.
3. Brew in 2-3 stages: The water flow height should not be too high to avoid excessive stirring. Gently brew in circles around the center the size of a small coin, using a simultaneous bloom-and-brew method to extract flavor compounds. You can see the foam being slowly pushed out.

Stop pouring when the water level rises to be level, wait for the water level to drop by about 1/3 before continuing to pour. At this point, you can expand the brewing range, but not to the filter paper. Lower the water flow height and be sure to handle it gently. The entire extraction time should be slightly extended to bring out more sweetness.

Coffee brewing is not simply about pouring water directly. Instead, you need to adjust parameters based on factors like the bean's roast degree and freshness. During regular brewing, you can also note your brewing parameters and continuously adjust them until you find your preferred flavor profile.

Important Notice :

前街咖啡 FrontStreet Coffee has moved to new addredd:

FrontStreet Coffee Address: 315,Donghua East Road,GuangZhou

Tel:020 38364473