Why Use Different Temperatures to Brew One Pot of Coffee? What is Three-Temperature Variable Brewing? What Water Temperature Should You Use for Pour-Over Coffee?

Understanding Over-Extraction in Coffee Brewing

Over-extraction is a common frustration that many coffee enthusiasts face when brewing coffee. As we all know, when a coffee becomes over-extracted, it develops obvious off-flavors and bitterness, making it difficult to drink. The main cause of over-extraction stems from an excessive extraction rate, but this can occur in different scenarios! The reasons for excessive extraction rate could either be overly extreme extraction parameters or issues with the grinding quality of your coffee grinder.

Solutions for Over-Extraction

If the issue is excessively high extraction parameters, we can reduce the extraction rate by adjusting these parameters. However, if over-extraction is caused by excessive fine particles from the grinder, it becomes difficult to adjust through parameter changes alone. But it's not without solutions - FrontStreet Coffee believes that sieving out fine particles or using variable temperature brewing would both be excellent options! Since FrontStreet Coffee has already shared the pros and cons of sieving fine particles multiple times, we won't dwell on that today. Instead, let's focus on sharing about variable temperature brewing.

What is Variable Temperature Brewing?

Variable temperature brewing, as the name suggests, involves completing a brew of coffee using different water temperatures. This method primarily affects the temperature of hot water during extraction, while other parameters can remain virtually unchanged. However, we need to understand that the "different temperatures" mentioned here don't refer to small differences of 2-3°C, but rather involve a significant temperature range.

The Origins and Principles of Variable Temperature Brewing

The first person to invent and use this method was Mr. Wu Zelin from Taiwan, China, who won the World Barista Championship in 2016 using this technique! It was precisely because of this achievement that variable temperature brewing became known to the world. When water temperature is higher, its extraction efficiency increases, making flavor compounds in coffee more easily dissolved; conversely, when water temperature is lower, extraction efficiency decreases, and flavor compounds dissolve more slowly. Variable temperature brewing utilizes this principle by dividing the hot water used for a brew into two (or possibly more) different temperatures, thereby controlling the quantity of substances extracted from coffee grounds at different times. Therefore, the specific timing of temperature changes can be adjusted according to our needs.

Different Approaches to Variable Temperature Brewing

For example, Mr. Wu Zelin's variable temperature brewing divided the pour into four segments (16g coffee, 1:15 coffee-to-water ratio, with segment water amounts of 40, 80, 80, and 40 ml respectively). The first two segments used 94°C hot water for brewing, while the last two segments used 90°C and 80°C respectively, creating a step-like temperature change. The advantage of this approach is that it allows concentrated extraction of sweet and sour compounds in the early stages, while using relatively cooler water in later stages when bitter compounds are about to be released in large quantities, thereby slowing their dissolution. Since the release of bitter compounds is inhibited, the coffee exhibits more outstanding sweet and sour characteristics. Meanwhile, the variable temperature brewing method used by Emi, the 2018 WBrC champion, involved a smart dripper and a three-stage process: low-temperature blooming and steeping (80°C), followed by high-temperature drip extraction (95°C), and finally low-temperature steeping (80°C) before opening the valve to finish. This approach aims to reduce the release of acidic compounds, making the entire cup of coffee smoother with heightened sweetness.

How to Implement Variable Temperature Brewing

Although we could also follow the competitors' approach by using multiple temperature-controlled kettles to obtain different temperature hot water simultaneously, this method is obviously too extravagant, as it requires equipping multiple brewing kettles. Therefore, FrontStreet Coffee recommends using cold water to adjust temperature during the brewing process! This way, we only need one kettle to achieve variable temperature extraction. The only drawback of this method is that it's limited to variable temperature brewing where temperatures decrease from high to low.

The "Devil's Brewing Method"

Among the various variable temperature brewing methods, there's one that FrontStreet Coffee particularly favors - the advanced version of Mr. Tetsu Kasuya's 4:6 method, known as the "Devil's Brewing Method." For details, you can directly click on the blue text to read more, but the general process involves dividing coffee extraction into three segments: the first two segments use high-temperature water at 92°C for drip extraction, while the last segment uses low-temperature water at 70°C combined with immersion extraction. Because the water temperature used in the final segment is very low (relatively speaking), this method offers a very high fault tolerance, making it easy to brew a cup of coffee that's high in sweetness without bitterness.

Demonstration with Natural ALO Coffee

The reason for favoring this method is simple: since we're already using such an extreme method as variable temperature brewing, why not add some flair to make the elaborate effort worthwhile? Therefore, FrontStreet Coffee will use the "Devil's Brewing Method" for today's demonstration. The selected bean is the newly arrived natural processed ALO, which typically displays rich magnolia, citrus, and pineapple notes under conventional brewing. The extraction parameters are as follows:

Coffee dose: 15g
Coffee-to-water ratio: 1:15
Grind size: EK43 setting 9, with 85% pass-through rate on a #20 sieve
Brewing method: Devil's Brewing Method
Dripper used: Hero variable speed dripper
Water temperature: 92°C, 70°C

First, we pour 30ml of hot water for blooming. The time is also thirty seconds, with the dripper valve kept open.

After blooming, we use a small water flow in a circular motion to pour 60ml of hot water.

Once the pouring is complete, we immediately add room temperature water to the kettle to lower the water temperature to 70°C.

When the hot water has finished penetrating, we close the valve and immediately pour the remaining 135ml of hot water in one go!

After steeping for thirty seconds, we can open the valve to release the coffee!

When the coffee has finished draining, we can remove the dripper and end the extraction!

Results and Conclusion

Total time: 2 minutes and 41 seconds! This cup of variable temperature brewed ALO is easy to drink because of the moderate temperature! Its flavor profile is also outstanding - mango, pineapple, and citrus with a very full juice-like texture, truly excellent! If you're someone who frequently experiences over-extraction due to excessive fine particles, trying variable temperature brewing might be worth considering~

Important Notice :

前街咖啡 FrontStreet Coffee has moved to new addredd:

FrontStreet Coffee Address: 315,Donghua East Road,GuangZhou

Tel:020 38364473