Calibration of grind size characteristics of Italian Coffee numerical reference of Grinding fineness of all kinds of Coffee machines

No matter which method is used to extract coffee, it is very important to find the right degree of grinding. the thickness of grinding will directly affect the stability of extraction and the performance of flavor. Espresso belongs to high temperature and high pressure extraction, which requires a higher degree of fineness of coffee grinding.

Extraction principle of Italian Coffee

Before the advent of espresso, coffee was brewed by soaking, and it took at least a few minutes to order a cup of coffee after a slow extraction. Espresso was invented in the early 19th century. In order to extract a cup of strong coffee in a short time, Italians thought of using steam pressure to pass high-temperature and high-pressure water through coffee pressed powder to speed up the original trickling extraction rate. With continuous improvement and update, our common semi-automatic / full-automatic espresso machine has been derived.

Using Italian coffee machine extraction, in order for the soluble flavor substances in coffee to be released into hot water in just a few seconds, coffee should have more contact with water, and the grinding degree must be very fine and uniform. Espresso is a pressurized short-time extraction, which also means that it magnifies all the performance, positive flavor and defects, so it is more demanding for grinding.

Requirements for grinding degree of Italian coffee machine

If a coffee shop has both espresso and hand-brewed coffee, it will be equipped with at least two different bean grinders. Among them, the coffee powder ground by the Italian bean grinder is like frosting, its thickness is about 150-300 microns, and the thickness and uniformity can not be observed by the naked eye, but we can use the extraction state of coffee and water to handle the correct grinding degree.

If the degree of grinding is slightly fine, the water will pass through the powder layer more slowly and it will be easy to over-extract. If the degree of grinding is a little rough, the water will easily pass through the powder layer, and it is easy to underextract, resulting in such a deviation, which may only be 0.1 of the grinding scale. So we usually observe the flow rate and taste of espresso in the brewing process to determine whether it is within the appropriate thickness range, and then make adjustments.

How to adjust the grindability of espresso every day?

When we get a bag of strange coffee beans, the first thing we need to do is to determine the degree of grinding if we want to make a good cup of coffee. If our grinding equipment has not been used, we do not know how to determine the appropriate scale range, we can first use a small amount of coffee beans to debug in different scale ranges. When the coffee powder is ground to the touch of flour, the coffee powder can be felt by hand. It is soft without roughness.

At this point, we can apply the common formula of Italian concentration for extraction. Qianjie recommends using a liquid separation ratio of 1:2, that is, 1 gram of coffee powder to extract about 2 grams of coffee liquid, the time between 20 and 30 seconds. For example, the front street uses a powder bowl with a capacity of 20 grams, that is, 20 grams of coffee powder and 40 grams of coffee liquid. If the time is less than 20 seconds, the flow rate is too fast; when the concentrate flow rate is more than 30 seconds, the flow rate is too slow. The fast flow rate means that the time for the water to pass through the coffee powder is too little, and the taste of coffee is often light or sour, so it needs to be adjusted carefully. Similarly, the slow flow rate means that the coffee powder is too fine, the water is difficult to pass through the powder layer, and the coffee is easy to taste bitter, so it needs to be thickened.

The research grinding scale usually depends on the experience accumulated on a daily basis. If the time difference from the target is less than 5 seconds, you can adjust 0.2 grid each time. If the time difference is too large, you can be bold and adjust 0.5-1 grid. Even if the time is too long to be too short, you can also lock the grinding scale range and slowly fine-tune to the target value.

The formula mentioned above in Qianjie is only for us to quickly find the suitable grinding range, it does not mean that the espresso extracted in this way tastes good. Finally, we still need to combine the characteristics and taste of coffee beans, according to our own experience to judge whether the extraction is qualified or not. If you are a barista, Qianjie believes that you should be able to find out the rules in many practical exercises produced in the store; if you just don't make a cup at home, it may require long-term learning accumulation, more records and summarization. this is more conducive to our rapid adjustment of good coffee.

If the taste of espresso is obviously bitter, but the concentration is moderate, it may be due to excessive release of bitter substances for too long, and the grinding degree can be fine-tuned. If the oil on the top layer of the coffee liquid is light and thin, it may be due to too much extraction at the end, which can reduce the weight of the coffee liquid, that is, less extraction, it is recommended to increase the ratio of powder to 1.5 to 1.7. When espresso is rich in flavor but with a short finish, you can properly extract more coffee liquid and try to adjust the ratio to 1Ru 2.5.

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