The heating control mechanism of Nova coffee machine is there with instructions in Chinese.

The heating control mechanism of Nova coffee machine is there with instructions in Chinese.

After that, we saw the above passage in many books and in the essence of BBS, which is regarded as the origin of Italian coffee (Espresso). The "impatient engineer of the early 20th century" described in the above paragraph means probably Luigi Bezzera. I don't know if Bezzera is impatient, but he made a coffee machine under steam pressure in 1901, not only because he was "impatient with dripping coffee for too long", but more importantly, he knew that too slow brewing time would directly affect the quality of coffee. ──, because the brewing time is too long, the coffee powder should not be ground too fine. Rough grinding means that fewer aromatic components can be extracted than fine powder. Fast is only the superficial reason, the pursuit of quality is the driving force of Espresso development!

Moreover, I can't agree that Bezzera alone 'invented' Espresso, although he was the first to try to make a commercial coffee machine under steam pressure and created the Espresso culture that is currently made in the bar and injects coffee directly into the guest cup. However, the coffee brewed by this kind of coffee machine still does not have the delicious taste of Espresso and is full of Crema. This is mainly because Bezzera's coffee machine uses the steam produced when the water boils, which forms pressure in an airtight boiler and pushes hot water into the coffee powder in the shower head. In order to make steam, the whole boiler must be heated to boiling, causing hot water near the boiling point to burn the coffee powder, lose the aromatic oil hidden in the coffee powder, and extract the doubly bitter coffee. There are two main reasons why coffee brewed on Bezzera's machine cannot form Crema:

The hot water for brewing coffee is too hot, resulting in the loss of oil.

The steam boiler cannot provide enough pressure.

Even so, exerting extra pressure to shorten the time it takes to brew coffee is still worth the effort. Just don't use steam, what should be used as a source of pressure? The further question is: how much pressure does it take to get the best extraction rate?

A brief history of coffee machine development Ⅱ

Desiderio Pavoni obtained a design patent for Bezzera in 1903, and he has been making the coffee machine since 1905. After that, Teresio Arduino began to produce similar coffee machines, and other producers followed suit. In the 1920s, coffee shops in Italy could see signs of this kind of coffee machine. But the Italians are obviously not satisfied with the results of the steam pressure coffee machine. The pressure should be increased by steam, but increasing the heat may burn the coffee powder during cooking, losing the aromatic oil hidden in the coffee powder and making it more refined.

Take out the doubly bitter coffee. Therefore, some people think: can it be directly pressurized on the hot water instead of boiling the water with steam as the pressure?

During the two world wars, people used the natural pressure of water from the faucet to increase the pressure of brewing coffee. The coffee machine uses electricity to quickly heat a small pot of water to the boiling temperature, each pot of water to make a cup of coffee, each pot connected to the faucet. As long as the operator gently press the pole on the small pot, the pressure of the faucet will push the hot water in the small pot to the coffee powder. According to the difference of water pressure in different regions, generally speaking, the pressure generated by this coffee machine is greater than the 1.5 atmospheric pressure produced by the steam pressure coffee machine. The height of this coffee machine is not too different from that of the steam pressure coffee machine, but the overall size is smaller. The appearance is more in line with the popular trend of the late 1920s and 1930s, replacing the arc of the steam pressure coffee machine with straight lines and geometric lines.