For more specialty coffee knowledge, please follow: Front Street Coffee (Frontsteet Coffee)

When we usually make pour-over coffee, we always do a bloom first, especially in filter-style brewing methods, which is quite common. So, is a bloom still necessary in immersion-style extraction coffee?

 What is a bloom?

It refers to gently, softly, quickly, and evenly pouring hot water over the coffee grounds when making pour-over coffee, to "activate" the coffee grounds and cause the coffee to release a large amount of carbon dioxide, making the coffee grounds form an upward swelling process—in other words, the bloom is actually a process of letting the coffee grounds release carbon dioxide.

In immersion-style extraction coffee, it means wetting the coffee surface to make the coffee puck expand rapidly and release carbon dioxide, so that the puck forms a good filter layer. Theoretically, the expansion space of the coffee grounds is about 1-2 mm, and the expansion creates uniform water-bubble gaps between the coffee particles, allowing water to pass through quickly and evenly. The role of pre-infusion is to make these coffee particles expand, forming gaps of uniform size, and letting the coffee aroma be fully released.

 Brewing experiment 

So we used the Clever Cup and tested separately with Front Street Ethiopia Yirgacheffe Red Cherry and Indonesia Front Street PWN Golden Mandheling.

Procedure

These two beans were tested separately with a bloom and with direct pouring. The details are as follows:

Grind size: Yirgacheffe [medium-fine grind, 80% passing through a No. 20 standard sieve]

PWN Golden Mandheling [medium grind, 70% passing through a No. 20 standard sieve]

Coffee dose: 15g

Coffee-to-water ratio: 1:15

Water temperature: 92°C for Yirgacheffe, 88°C for Golden Mandheling

Bloom version: First pour 30g of water and bloom for 30 seconds, then pour to 225g and wait 3 minutes 30 seconds, for a total extraction time of 4 minutes. Then move the Clever Cup onto the sharing pot to filter.

Direct pour version: Directly pour 225g of water and wait 4 minutes, then move the Clever Cup onto the sharing pot to filter.

 Flavor comparison 

Yirgacheffe Natural Red Cherry

Bloom version: Concentration: 1.37%, thick mouthfeel, berry sweetness, rich fermented aroma.

Direct pour version: Concentration 1.33%, citrus and berry acidity, balanced mouthfeel, slight fruity aroma.

PWN Golden Mandheling

Bloom version: Concentration: 1.40%, mellow mouthfeel, rich nut, cocoa, and caramel flavors, with herbal aroma.

Direct pour version: 1.33%, thick mouthfeel, sugarcane and chocolate flavors, more comfortable to drink.

In terms of flavor, the one with the bloom step tastes richer and thicker than the one with direct pouring and immersion. Front Street believes that because a small amount of water is used for the bloom, the subsequent pouring has an impact force that stirs the coffee bed, which compared with pouring all the water in one go with a large stream produces greater extraction efficiency, thus making the coffee richer and more intense.

Actually, Front Street believes that for immersion-style brewing methods like the Clever Cup, you might as well try stirring with a stirrer so that all the grounds can be extracted evenly.

The above content is compiled by CoffeeHunters, a coffee news website.