Can Hot and Warm Water Be Used to Make Cold Brew Coffee? What Unique Characteristics Do They Create?

Understanding Traditional Cold Brew

Wait! I know you have something to say, but before that, listen to FrontStreet Coffee~ Here's the deal: Typically, cold brew coffee takes 8-12 hours to prepare, partly because room temperature/cold water extracts slowly, and partly because it needs time to ferment. That's why we usually leave it to steep overnight.

The Quest for Quick Cold Brew

But, some friends might suddenly have the urge and don't want to wait through the long night, wanting to drink cold brew coffee the same day. Is there a way to make it quickly and enjoy it immediately? The answer is definitely yes! Since room temperature/cold water extracts slowly, we can choose to increase the water temperature to accelerate the extraction rate, thereby reducing part of the extraction time. This way, we can significantly reduce the preparation time!

The Science Behind Cold Brew Extraction

At this point, some observant friends might ask: "But isn't that just hot water? Guess why cold brew is called 'cold' brew?" Good point! The significance of cold brew coffee lies in its extraction through low temperatures! Low-temperature extraction allows coffee to obtain more abundant floral and fruity aromas than high-temperature extraction! The reason is due to the "slower extraction rate," to put it simply, it reduces the release speed of all substances from the coffee particles! Acid, sweet, and bitter are the three main flavor compounds released during coffee extraction! Although they are released simultaneously at the beginning of extraction, they have different dissolution rates, so their mass release times vary! The first to be released in large quantities are acidic compounds, followed by sweet compounds, and only when these two compounds are mostly extracted do bitter compounds begin to release in large quantities!

Why Traditional Cold Brew Isn't Bitter

In other words, the reason why our traditionally made cold brew coffee isn't bitter and has more abundant floral and fruity aromas is because the extraction hasn't reached the point where bitter compounds are released in large quantities! By reducing the proportion of bitterness, acidic and sweet compounds have more room to shine!

The Optimal Temperature for Quick Cold Brew

Therefore, we cannot use hot water instead of room temperature water to make cold brew! Because, in just a few minutes, the 30% of soluble substances in the coffee will be completely extracted! Therefore, if we need to increase the extraction rate, we can only slightly increase the temperature of the room temperature water we normally use. This way, we can reduce extraction time while preventing the extraction of bitter flavors!

So, what temperature water should we use for quick cold brew? In an experiment six months ago, FrontStreet Coffee discovered that 40°C warm water can better produce quick cold brew coffee!

Experimental Comparison

However, after publishing the article, some friends raised this question: Using 92°C hot water for blooming, then adding room temperature water for rapid cooling and extraction—wouldn't this avoid over-extraction and have better effects? Excellent! So for this experiment, we can add a comparison segment: For "quick cold brew coffee" preparation, should we use warm water directly for immersion extraction, or use 92°C hot water for "blooming" and stirring, then add room temperature water for immersion extraction!

Yesterday evening, FrontStreet Coffee had already prepared a regular cold brew coffee for comparison, so the coffee beans used for today's cold brew will be consistent with it: Colombia·Hanami. It has full-bodied fruity acidity, rich floral aromas, and rare pink pepper flavors! With distinct layers, it's the most suitable bean for today's experiment (and it's indeed delicious).

Regular cold brew coffee parameters: 20g coffee powder, water temperature 23°C, coffee grind size at Ek43's 10 setting, powder-to-water ratio 1:12, refrigeration time 10 hours.

Warm water cold brew coffee parameters: 20g coffee powder, water temperature 40°C, coffee grind size at Ek43's 10 setting, powder-to-water ratio 1:12, refrigeration time 4 hours.

Hot water blooming cold brew coffee parameters: 20g coffee powder, water temperature 92°C & 23°C, coffee grind size at Ek43's 10 setting, powder-to-water ratio 1:12, refrigeration time 4 hours.

Let's start making them directly. The all-warm water group directly pours 20g coffee powder and 240ml of 40°C warm water into the pot and stirs!

The hot water blooming group, on the other hand, pours 20g coffee powder and 40ml of 92°C warm water into the pot and stirs! After stirring evenly, add 200ml of 23°C room temperature water and stir again!

Then both are sealed and placed in the refrigerator for 4 hours of cold storage!

Tasting Results

Refrigeration complete! We take them out, filter them separately, then taste them in sequence to see what differences exist between them!

Regular cold brew coffee: Full-bodied, round berry flavors, with very distinct pink pepper notes and obvious fermentation, combining to create something like spiced strawberry juice—excellent!

Cold brew coffee made with 40°C warm water: Also has excellent berry flavors with prominent sweetness, but the roundness is slightly weaker than regular cold brew. Pink pepper flavors are also well-expressed, but due to the shorter steeping time, although there are fermentation notes, they are relatively weak.

Cold brew coffee with 92°C hot water blooming + room temperature water: Compared to the first two cups, its flavor is more like iced pour-over coffee, with balanced acidity, sweetness, and bitterness. In terms of fermentation, it's the weakest of the three.

(Due to different levels of immersion extraction, the three cups of coffee have different depths of color)

Conclusion

So, it can be seen that the "quick cold brew coffee" made with 40°C warm water immersion is the closest to regular cold brew! Although the overall experience may not be as rich as regular cold brew, its ability to produce cold brew coffee with fermentation notes and well-expressed flavors in a short time can already satisfy the cravings of friends who are eager for their coffee!

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FrontStreet Coffee (FrontStreet Coffee)

No. 10, Bao'an Front Street, Yandun Road, Dongshankou, Yuexiu District, Guangzhou City, Guangdong Province

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