What is the correct water temperature for espresso brew? What degree of water should I use to make coffee best?

When Qianjie previously shared knowledge related to espresso extraction, he would focus on the impact of parameters such as powder amount, proportion, grinding, time, and pressure on extraction. In addition, the operation essentials of powder receiving, powder distributing, powder pressing, and buckling the handle are also analyzed. There is only the water temperature, which Qianjie always simply mentions. This does not mean that the water temperature is not important, but it is troublesome for many coffee machines to adjust the water temperature, so Qianjie simply sets it to a fixed value, and then adjusts other parameters to match the fixed water temperature to extract good espresso.

With the popularity of various complex operations such as pressure swing extraction in recent years, the water temperature of coffee machines has also become a parameter that changes frequently. But what everyone needs to know is that unlike hand-brewed coffee, changes in the water temperature of the coffee machine will have a lot of impact.

What does the water temperature of the coffee machine affect? As we all know, the biggest impact of water temperature on extraction is efficiency. When the water temperature used is higher, the extraction efficiency will be higher, and the flavor substances in the coffee will be quickly dissolved; when the water temperature is lower, the extraction efficiency will be lower, and the dissolution rate of the flavor substances will be reduced.

In addition to extraction efficiency, the water temperature of the coffee machine will also affect the flow rate of coffee liquor, or the speed of water discharge. When other parameters are the same, the higher the water temperature used for extraction, the slower the flow rate of coffee liquor will be. Conversely, the lower the water temperature used for extraction, the faster the flow rate of coffee liquor will be.

If you have read Qianjie's tweet the day before yesterday, you will know that this is because the water temperature determines the speed at which the powder cake expands and exhausts. High water temperatures allow the powder to expand more quickly and release various substances hidden in the coffee powder. The expanding powder cake reduces the gap between the coffee grounds, and the released gas will be wrapped in the lipids of the coffee beans to form bubbles, creating resistance to the water flow. So when the two are superimposed, the flow rate of coffee will change.

If you still don't understand the principle here, it's better to experience it through practical operation. When we turn on the machine every morning, it takes nearly 20 minutes for the coffee machine to heat the boiler and form steam. During this time, the coffee machine The extraction function can be operated, but the water temperature is relatively low, usually around 60°C.

So, we can try at that time what state extraction concentration is like at a lower water temperature. Then you will find that the flow rate of coffee liquor can be said to be quite fast. This is because the carbon dioxide emissions are not sufficient and the expansion rate of the powder cake is not enough, so the flow rate is relatively slow.

The last factor that can be affected by water temperature is the richness of the oil. Qianjie mentioned earlier that the water temperature will affect the emission rate of carbon dioxide, which is the main component of oil. Therefore, when other parameters remain unchanged, the higher the water temperature used, the extracted oil will be, the richer it will be, and vice versa.

The above is the impact of different water temperatures on the extraction of espresso. So the question arises: How much water temperature should we use to extract espresso?

What is the most suitable water temperature? In fact, just like Qian Jie shared in the tweet "How much water is best to use to make coffee?", in addition to water temperature, grinding, ratio, and time are the main parameters that will affect the extraction of a cup of coffee, so the specific water temperature to use still needs to be matched based on them.

There is such a hypothetical experiment in the book "The Extraction Science of Espresso Coffee": Italian baristas like to extract espresso with water at 85 - 91°C, while American baristas like to extract espresso with water at 92 - 96°C.

The reason why there is such a difference is mainly due to their different proportions. The Italian standard is to use 7 grams of coffee powder and then extract 1 ounce of espresso, while the United States uses 18 to 21 grams of coffee powder to extract 1 ounce of espresso. The ratio, time, and grinding are all different, so the water temperatures they use are also different.

But conversely, as mentioned at the beginning, you can also set the water temperature to a fixed value and then adjust other parameters to match the fixed water temperature.

Generally, the initial water temperature of the coffee maker at the factory will be set in the range of 92°C to 96°C. This range is a very suitable temperature range and will not be too low or too high. As long as the initial water temperature of the coffee machine is within this range, unless you have any special extraction needs, we almost don't have to make changes to it.

Then we apply the golden extraction formula of espresso coffee (1:2 powder-to-liquid ratio, 25 - 35s extraction time) to frame the liquid weight and time, so that we can quickly extract good espresso by adjusting the grinding and fine-tuning the liquid weight.

It is worth mentioning that... Like making coffee by hand, the water temperature we can now set is the water temperature in the boiler rather than the actual water temperature during extraction. Because water passes through various pipes from the boiler to the water distribution network, the final actual extraction water temperature will be several degrees different from the set temperature due to heat absorption.

Especially when espresso coffee has not been extracted for a long time, the difference between the water temperature and the setting will be even greater. Therefore, when the coffee extraction interval is too long, it is best to empty the hot water once before clamping the handle. This will not only help us correct the water temperature, but also clean the water distribution network once to remove the "residue"(that is, coffee grounds) attached to the water distribution network.

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