What is the right degree of grind for espresso? What should I do if the pressure value of the coffee machine cannot go up?

Surprise questions! What is the biggest difference between the extraction method of Italian coffee machine and that of brewing, brewing and brewing coffee?

Yes, it's the difference between stress! The former is pressurized extraction, while the latter is atmospheric pressure. Because of the pressure, espresso can be extracted in a very short time! The golden Crema at the top of the concentrate is the exclusive product of pressurized extraction. So we can know that pressure is a very important parameter for espresso machines. Generally speaking, the extraction pressure of the coffee machine will float around the range of 9bar, in this range, espresso can not only be extracted quickly, but also very rich. But many friends who just bought the coffee machine react forward, the extraction pressure when using the coffee machine is very difficult to climb to 9bar, has been in the 5bar~7bar range, the extracted coffee is as light as water, very sour. So why did this happen?

Why is there not enough pressure during extraction? Let's start with what "stress" is. The so-called pressure, the physical explanation refers to the force that occurs on the contact surface of two objects! To put it simply, it is the force acting vertically on the surface of objects as a result of squeezing each other, which is called pressure. When applied to the coffee machine, it is the force that water exerts on pressed powder. The upper limit of pressure is mainly determined by the resistance of pressed powder. The greater the resistance of pressed powder, the more difficult it is for hot water to permeate, so the higher the pressure it needs, the higher the pressure provided by the coffee machine. But when pressed powder resistance is not enough, hot water can easily penetrate pressed powder, and even if we want the coffee maker to increase the pressure, it can't do it. Therefore, the resistance of pressed powder is very important.

When hot water can quickly penetrate pressed powder, it means that the contact time between hot water and coffee powder is shortened, and the extraction efficiency will be greatly reduced without the help of pressure. with the same amount of liquid, the flavor substances in the coffee can not be extracted sufficiently, and the coffee will appear the negative condition of light and sharp acid. Therefore, if we want to extract enough flavor substances in a short time, we need to increase the resistance of pressed powder to improve the extraction efficiency. You might as well guess what aspects can increase the resistance of pressed powder, and then correct the answer with Qianjie.

1. Fine grinding

In many cases, the reason why pressed powder does not have enough resistance, coffee machine pressure does not go up, to a large extent, is not found the right degree of grinding. When the particle size of coffee powder is too thick, the gap between the powder and the powder will be larger, hot water has a lot of space to flow, naturally there is no need for high pressure extraction. And fine grinding is the best solution! The specific adjustment we need to decide according to the current extraction time, when the gap between the concentrated extraction time and the extraction time in the formula is too large, the more we need to fine-tune the scale.

Second, to increase the amount of powder besides grinding, the amount of powder used is also an important problem. Many friends may not want to eat too much caffeine, so they use less powder. But we should know that every powder bowl has a recommended amount of powder. This limit exists to ensure a reasonable space between pressed powder and the head. Too little or too much is no good.

And when the amount of powder we use is much lower than the recommended amount of powder in the powder bowl, it not only means that the distance between the pressed powder and the cooking head is more distant, but also means that the thickness of the powder layer has been greatly reduced, so there is not so much powder that the hot water has to pass through, so the pressed powder can be broken more quickly, and there is no need for the coffee maker to provide too much pressure. Therefore, the amount of powder is also a parameter that can determine the upper limit of the pressure value. We try our best to use the recommended amount of powder in the powder bowl. If the gap is too large, it would be more appropriate to change the powder bowl in Qianjie.

Third, the strength of powder pressing should not be underestimated. The function of pressing powder is to make the relationship between powder and powder closer, so that coffee powder can coalesce together and form resistance. But when we do not apply enough force when pressing the powder, then pressed powder cannot be formed, and the loose coffee powder will leave a lot of channels for hot water to circulate, and since there is no resistance, there is no pressure to make a breakthrough! So the force we have to exert when pressing the powder must be enough, so that the coffee machine has room to provide pressure.

In addition to these routine operations, the choice of powder bowl can also change the pressure limit of the coffee maker. The number and size of holes in the powder bowl can control the flow rate of hot water, thus affecting the pressure of the coffee machine. However, in the absence of special extraction requirements, we only need to pay attention to the above three factors.

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