Coffee knowledge Popularization-- Italian espresso

To achieve a cup of espresso (espresso), the most important factor is stable pressure and stable temperature.

Sometimes those who encounter half a bottle of water will say that this term is out of date, and now the best semi-automatic coffee machine is variable pressure.

Indeed, since 2004, the real variable pressure coffee machine has been born, gradually spread all over the world, and began to enter China in recent years.

But the pressure swing coffee machine is not random, its pressure control requirements are far greater than the traditional semi-automatic Italian coffee machine, coupled with the price of more than a hundred thousand is not affordable to the average family.

To quote the explanation of Brother Bird, the Great Coffee God, "how to understand the variable pressure technology: to reach the specified pressure value at any time, and to be stable, and to remain unchanged after changing to the specified pressure value again, is the real variable pressure."

Since we can't afford the Tuhao coffee machine, we should return to the traditional espresso machine and return to espresso's golden rule of "extracting 1 ounce (30ml) of espresso (espresso) in 25-30 seconds at 90-92 degrees Celsius under 9bar pressure."

Although this golden rule is still controversial in professional coffee forums in recent years, 9bar pressure is basically not controversial, so a bunch of coffee machines boasting 15bar or higher actually refers to the most high pressure of the coffee machine, which is of little significance, and is generally used to fool newcomers. Stable pressure and stable temperature are the criteria for measuring Italian coffee machines.

Now that you know the two most important factors of espresso (espresso), you can choose the espresso machine, all traditional espresso machines are designed around these two factors.

In the Italian coffee machine, the influence pressure value is mainly the pump, the pump is divided into the vibration pump and the rotary pump, the pressure curve of the vibration pump fluctuates, and the pressure curve of the rotary pump tends to be a straight line, but the machine of the rotary pump is not less than 8000 at present.

In the Italian coffee machine, the temperature value is mainly affected by the size of the boiler or heating block, as well as good heat conduction materials, there is an obvious difference between the toy machine and the professional Italian coffee machine. In general, many standard toy machines are equipped with small boilers (below 200ml) or small heating blocks, so it is difficult to achieve a stable temperature, and the temperature fluctuates greatly in the process of coffee extraction. The machines of many small household appliance brands are like this (such as Cankun, Delong, Electrolux, etc.). After all, these brands are not professional coffee makers. Another thing to consider is a good heat conduction material, a good machine has a better circuit and pipeline design, using copper or stainless steel as the main material of the coffee machine, they have good thermal conductivity (to ensure uniform and stable temperature). Otherwise, it is still more than 90 degrees from the boiler to 70 or 80 degrees from the coffee machine, which will be more obvious in the low temperature environment.