The Hot expansion and Cold shrinkage of Coffee-an introduction to the difference between Italian Coffee and fancy Coffee

Coffee beans cannot be 100% integrated into water, and soluble matter in coffee accounts for a percentage of coffee powder that was previously extracted. To put it more popularly, how much substance in the coffee powder has been incorporated into the coffee liquid. Therefore, the extraction rate is, TDS/DOSE (gram weight of powder) there is a very important concept, the reasonable extraction rate will be between 18% and 22%. If we extract too much, we will drink bitterly and have a mixed smell. If it is less than 18%, the coffee we often drink will be sour. It must be mentioned that whether it is espresso or filtered coffee, the extraction rate is in this category.

All modern coffee extraction is the two core processes of soaking and filtration, which belongs to the category of physics, and there is basically no chemical change in the process. The differences in the thickness of coffee powder, the length of soaking time, the method of separation and filtration, and so on, have created a wealth of coffee brewing utensils and techniques. Although the core process of coffee extraction is the same, according to the significant differences in pressure and time used in coffee extraction, modern coffee extraction methods can be simply divided into two types:

First, Italian Rapid espresso (Espresso), invented in Italy, extracts 25 milliliters of espresso in 25 seconds at 9 atmospheric pressure and 92 degrees water temperature. This is significantly different from other coffee extraction methods, which can be done under unnatural conditions, reflecting the intervention of science and technology. Espresso Espresso can generally be made by Italian semi-automatic coffee machine and full-automatic coffee machine. A good Espresso requires higher price and quality of coffee machine and bean grinder. Semi-automatic coffee machine is only suitable for commercial production of coffee operators and is not suitable for ordinary families. Because of its convenience and speed, full-automatic coffee machine has been accepted by family enthusiasts a few years ago, and there are many optional models now. Dazzling, but the coffee made by the automatic coffee machine is really not flattering, it can only be called the beverage machine is more appropriate, in addition, the internal structure of the automatic coffee machine, after using for a period of time, the parts that come into contact with the powder are moldy and there is no good way to clean up, which can not be solved. In the past two years, under the impact of hand-made freshly ground coffee, the market has gradually shrunk.

2. Filter drop method

The drip filtration method can make the beans show the original taste directly, and can correspond to various baking degrees. Just the operation process requires a little skill, for example, if the drip filter core, astringent strong coffee, it is necessary to use roughness grinding, so that hot water quickly through the coffee powder, more or less can be adjusted. Shorten the "stuffy steaming" process to make the overall taste lighter, but also can adjust the original taste is too strong, too bitter taste. The trickling filtration method has this kind of variability. The most suitable degree of grinding is moderate grinding. It is inappropriate to be too thick or too thin. Pick up a pinch of coffee powder in your hand, if it feels rough, it is best to press different filtering supplies, so that the water flow is not too fast or too slow, and the dripping water flow is a suitable line. Hot water temperature is about 82-92 ℃, according to different beans, different baking degree fine adjustment, need more practice, find suitable for their own is the right. The aroma of coffee using drip filter is more likely to escape than when extracting commercial coffee. After all, there is no way to be exposed to external air, which may be the only weakness of trickling filtration, so if you want to drink good coffee, you must be freshly ground coffee beans and how much powder you need to grind. In addition, it is easy to highlight some specific flavors when extracting at low temperature, so care must be taken. Compared with low-grade coffee, good individual coffee has no miscellaneous flavor, so it tastes good when it is cold.

Immersion extraction (Steep Extraction) is a more natural and simple way to extract coffee, and the extraction temperature is close to 85-92. It can be subdivided into: