An introduction to the common ways of making coffee when drinking coffee

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Instant coffee powder

The focus of the manufacture of instant coffee powder is to dry the boiled espresso liquid (powder), and there are two methods: "spray drying" and "freeze drying".

Spray drying means that the espresso liquid is sprayed into a fog with a nozzle, and then injected with hot air to let the water evaporate instantly, and then produce fine coffee powder. Freeze-drying is to freeze the concentrated coffee liquid at a temperature of minus 40 degrees C, and then send it to the vacuum chamber, where the water will skip the state of the liquid and directly become a gas (the sublimation of water), leaving coffee powder at last; because there are caves that originally contain water, the powder particles will be relatively rough.

The characteristic of freeze drying is that the espresso liquid is not heated, so it can better retain the original flavor of the coffee.

Siphon coffee maker

The siphon pot (Siphon), which originated in Germany, is a tool that uses the pressure caused by boiling water to make coffee. The siphon pot is constructed as an upper and lower pot connected by a pipe in the middle, and the lower pot filled with hot water will first be heated by an alcohol lamp or a gas lamp. Because at 1 atmospheric pressure, the volume ratio of 1 gram of liquid water to 1 gram of water vapor is 1100, when the volume of steam in the kettle increases with temperature, the liquid water can be easily pushed through the conduit to the upper pot filled with filter cloth and coffee powder, and the water will continue to be supported by a continuous stream of steam on the pot.

When the heating stops, the air in the lower pot gradually cools and shrinks, while the coffee liquid that has been soaked in hot water in the upper pot will flow back to the lower pot because it has lost the support of steam, and the coffee grounds will be blocked by a filter cloth and left in the upper pot. Finally, remove the upper pot and you can enjoy the coffee in the lower pot.

Because the water temperature is too high, the coffee powder will be scorched to cause bitterness, the soaking for a long time will produce astringent taste, and excessive stirring will produce sour taste, so the siphon pot needs considerable experience to be able to use the appropriate tool.

Espresso machine

Espresso (Espresso) is made by compacted coffee pressed powder with hot water at about 90 degrees Celsius at a force of about 9 atmospheres. Usually, one cup is only 30 milliliters and has a floating reddish-brown foam oil (Crema). It has the characteristics of fast brewing and high concentration, so it needs to be cooked by a special machine.

When coffee powder comes into contact with 90C hot water, it releases carbon dioxide, as well as essential substances such as oils and spices in coffee powder. Because carbon dioxide has its own gas pressure, water also has its surface tension, and high-pressure water at nine atmospheric pressures happens to have a gas pressure equal to carbon dioxide, so it allows water to enclose carbon dioxide, the essence of coffee beans, to form Crema.

Espresso is usually used as the basis for mixing coffee drinks, such as lattes, cappuccinos, caramel macchiato and mochas.

Mocha pot

The mocha pot, also known as the Italian coffee pot, is a three-layer teapot-shaped stove originated in Germany. Its principle is the same as the siphon pot, and it also uses the pressure of boiling water to cook coffee.

The difference is that the water pushed up by the pressure first passes through the middle layer with coffee powder and filter, and then reaches the empty container at the upper layer; the water from the siphon pot becomes coffee liquid at the upper layer and then flows back to the lower layer, while the water from the mocha pot does not flow back as soon as it rises to coffee.

In addition, because the mocha pot has the structure of a pressure valve, it can also set the pressure conditions when extracting coffee, and then create a Crema.