What is the best water temperature for hand-brewed coffee? Effect of brewing temperature on flavor and taste of coffee

Everyone tends to use a higher temperature to extract the water temperature of hand-brewed coffee, because high temperature can not only improve the extraction efficiency, but more importantly, it can produce rich sweet and sour aromas. Basically, the water temperature used to make coffee by hand is rarely lower than 80 degrees Celsius. So, is it possible to make coffee at a temperature lower than this?

This idea was born in Qianjie because recently there was an office friend who wanted to "play" with hand-brewed coffee in the office. the only thing that could produce hot water in the office was the water dispenser, which could only be heated to about 70 degrees Celsius at most. In our experience of making coffee, this simply does not reach the water temperature needed to make coffee by hand. However, 70 degrees of water may not be able to make coffee! If we take all the parameters apart, forget the subjective things such as flavor, and just talk about the effect of water temperature on the extraction rate of coffee, the answer is very simple, that is, the extraction efficiency, that is, the unit solubility. Just like we dissolve the granule, the higher the temperature, the faster the granule dissolves and the lower the temperature, so it takes more time for impact dissolution, and stirring is needed to speed up the dissolution if necessary.

The same is true for brewing coffee, when the water temperature becomes lower, can the same extraction rate be obtained by prolonging the extraction time? just like the way ice drop coffee is made, the temperature of ice water is about 7 degrees Celsius, and the extraction efficiency is very low at this temperature. but it can be made up for by 6-8 hours of long-time extraction.

So Qianjie came to test whether this is feasible. For the water temperature, Qianjie chooses 70 degrees Celsius, which is also the temperature reached by the corresponding drinking water heating machine. The coffee beans used are Panamanian flower butterflies, and the flavors flushed out with the standard parameters of Qianjie are jasmine, lemon, honey, oolong tea and so on. To prolong the extraction time of coffee, the more common methods in hand-brewed coffee are segmented water injection, control of water flow, fine grinding, and replacement of slower filter cups. So Qianjie uses all these methods, and the front street of the filter cup uses the infinite filter cup of Hario. Of course, those with slow flow rate such as fan-shaped filter cup and Kono filter cup can also be used.

Grind Qianjie uses the EK-43s 5.5scale (usually uses 10 scales), despite the difference of almost twice the scale, in fact, the thickness level of grinding is not exaggerated as we imagine, sifted with No. 20 sieve is 93% (for hand-brewed coffee is relatively fine). The proportion is still 1:15. In the stage of water injection, multi-stage water injection and small flow water injection are used in Qianjie, in order to prolong the extraction time as much as possible. The first injection of 30ml steaming for 30 seconds, followed by injection of 70ml, when the coffee liquid streamer can see the powder bed, continue to inject 65ml, also wait until the last amount of 60ml water is injected when the powder bed is seen, and the time for the coffee liquid to be fully filtered is 3 minutes and 33 seconds. After brewing, the coffee powder layer shows a muddy state, which shows that the coffee powder is still quite fine.

Qianjie first measured the concentration of coffee liquid with a concentration meter of 1.49%, which is a very high concentration for hand-brewed coffee, and the extraction rate of coffee is calculated to be 20.5%. Then taste, first from the aroma, the whole cup of coffee does not have a fresh flower fragrance, smells like a very sweet caramel flavor. Qianjie was a bit surprised by not feeling the discomfort caused by the full-bodied coffee. The sour taste of the whole cup of coffee is not obvious, the sense of sweetness is very strong, the rich sweetness of brown sugar. But there is some bitterness at the end of the paragraph that makes people uncomfortable. As a result, the front street has made some minor adjustments to change the grinding degree to 6.5, which is about 90% of the pass rate of the No. 20 screen. Qianjie brewed again in the same way, and this time the extraction time did not decrease too much, until the coffee in the filter cup was finished in 3 minutes and 20 seconds.

Similarly, Qianjie first used the concentration meter to measure the concentration of 1.46%, the concentration did not reduce too much, and the corresponding extraction rate was 20.09%. The aroma of this cup of coffee is not filled with the scent of flowers, but smells like sweet potato sugar water. The acidity of this cup of coffee is a little more sour than that of the previous cup, a bit like honey, sweet like fruit, very sweet, and tea at the end. Although this cup is obviously different from the standard coffee flavor, this cup tastes really good. Next, Qianjie adjusts the grinding degree to 7.5 (the pass rate of screen 20 is 87%) to test whether the flavor will be better. Under the condition that only the grinding degree is changed, the extraction time is 3 minutes and 02 seconds.

Qianjie measured that the concentration of this cup of coffee was 1.35%, and the extraction rate was calculated to be 18.55%. Similarly, there is still no flower fragrance in the aroma, which smells like the sweetness of some preserved fruit. The sour taste of the fruit is obvious, like the sweetness of small green mandarin and honey. However, the middle and back part is similar to the taste of southern apricot. Finally, for the extraction rate, the decrease of temperature can be made up by prolonging the extraction time. But for flavor, especially aroma, it is impossible to reproduce. High water temperature can extract rich floral and fruity aromas and more sour flavors in the first stage of extraction. With the decrease of water temperature, these flavor substances are not extracted higher, and due to the prolonged extraction time and the release of sweet and bitter substances, the performance of the whole cup of coffee is sweeter and more balanced. In the brewing process, the extraction time also determines whether the coffee is more bitter, sweeter, or more sour. For example, in this test, using a water temperature of 70 degrees Celsius and controlling the extraction time at about 3 minutes to 3 minutes and 30 seconds, the sweetness of the first cup tends to be bitter, and the third cup tends to be sour in 3 minutes and 02 seconds. If you use a lower water temperature, such as 40 or 50 degrees, it may take longer to extract and the flavor will be more balanced (uncharacteristic).