Does Cold Brew Coffee Need to Bloom? The Correct Way to Brew Cold Brew Coffee! What is Cold Brew Coffee? How Do You Make Cold Brew Coffee?

The Experiment with Bloom in Cold Brew Coffee

Cold brew coffee remains a beloved beverage even in cold winters due to its simple and convenient preparation method. Recently, a claim about cold brew coffee has resurfaced: blooming coffee grounds with hot water before the cold brew process results in better-tasting coffee compared to cold brew without blooming!

As we know, traditional cold brew coffee has always used a full low-temperature immersion extraction method. We simply need to mix water and coffee grounds, seal the container, and place it in the refrigerator for immersion. Adding hot water blooming before immersion clearly contradicts traditional cold brew methods. But can this approach really make cold brew taste better? Let's start our experiment and verify the results!

Extraction Experiment

To better distinguish the differences between the two methods, FrontStreet Coffee will use a standard processed coffee bean with relatively fresh flavor characteristics - the Guji 8.0 from Sidamo. All extraction parameters remain identical except for water temperature. The parameters are as follows:

• Coffee dose: 25g
• Grind size: Ek43 setting 10, with 80% pass-through rate on #20 sieve, consistent with hot pour-over
• Coffee-to-water ratio: 1:12
• Steeping time: 8 hours

The regular cold brew is quite simple! As we know, just mix the grounds with a certain proportion of room temperature water in a container, stir well, seal, and place in the refrigerator.

Now let's make the cold brew with the blooming step! We'll first use 40ml of 92°C hot water to wet the coffee grounds for a thirty-second bloom!

After thirty seconds, pour in the remaining 260ml of room temperature water, stir well, then seal and place in the refrigerator for cold immersion.

After 8 hours, we'll remove both coffee containers, filter out the coffee grounds, and conduct separate tastings.

Tasting Results

Indeed, there are certain differences between the two. The regular cold brew Guji exhibits flavors of strawberry, citrus, honey, and melon, with high sweetness and a refreshing taste. The cold brew with blooming doesn't show significant differences in flavor characteristics, but it has a relatively higher concentration.

Why These Differences?

Although cold brew coffee with added blooming shows concentration changes, we need to understand that the main factor changing the cold brew coffee isn't the blooming action itself, but rather the parameters we use to complete this step. The principle is simple - we just need to understand the usual effect of blooming on coffee. When we normally brew coffee, the purpose of blooming is to release carbon dioxide trapped in the coffee grounds. Because pour-over coffee is a drip extraction method, water and coffee grounds don't maintain continuous contact. Since we need to extract flavor compounds from the grounds in a short time, we need the blooming step to release carbon dioxide that would hinder stable extraction.

Cold brew coffee, however, is an immersion extraction method. Simply put, immersion involves steeping coffee grounds in water for contact extraction. Because it requires a relatively long time and water and grounds remain in continuous contact, carbon dioxide in the coffee grounds doesn't affect extraction. Therefore, we rarely see blooming steps used in methods like French press, cupping, or siphon brewing because it's unnecessary. The same principle applies to cold brew coffee.

The True Factor: Water Temperature

At this point, everyone should understand why cold brew coffee with and without blooming produces differences - it's due to water temperature. The higher the water temperature, the faster flavor compounds dissolve in coffee, and vice versa. Cold brew coffee requires long extraction times precisely because the water temperature isn't high, requiring gradual extraction of compounds from the grounds. When we bloom with 92°C hot water, this hot water not only serves the blooming purpose but also affects the overall water temperature during subsequent immersion. Regular cold brew uses approximately 25°C water during immersion, while cold brew with blooming, affected by this small amount of 92°C hot water, reaches approximately 32°C overall temperature after adding the remaining water to reach the target volume. Because the immersion temperature is higher, flavor compounds dissolve faster, resulting in naturally higher coffee concentration under equal extraction time. (Right side shows cold brew with blooming)

Conclusion

In summary, we can understand that blooming isn't the main factor affecting cold brew coffee - water temperature is. Despite this, the introduction of hot water does cause some changes in compound release, which is undeniable, but the impact isn't significant, so FrontStreet Coffee won't elaborate further~

As for whether blooming is necessary, it's a personal choice. If you want to shorten cold brew steeping time, you can add this step to reduce extraction time. But if you're like FrontStreet Coffee and use cold brew simply for convenience (I'm not saying I am)... then stick with the regular method, since both taste great~ Extending steeping time or increasing stirring can achieve the same effect (in terms of concentration).

Important Notice :

前街咖啡 FrontStreet Coffee has moved to new addredd:

FrontStreet Coffee Address: 315,Donghua East Road,GuangZhou

Tel:020 38364473