The basic principle of Coffee extraction how to extract Coffee

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1. Ratio of coffee to water: to put it simply, in the same 150cc cup, the higher the coffee content, the stronger the taste, while the more water, the lighter the taste. But where is the ideal extraction we need? It depends on our purpose. Like ordinary drip coffee, we want a sweet and refreshing taste, so we use a lower coffee-to-water ratio, while espresso aims to extract coffee as syrup-like coffee in a short time, so use a higher coffee-to-water ratio. In the case of a cup of coffee, we expect that the weight of coffee released into the water is about 18-22% of that of coffee. It can also be said that the exchange rate of coffee and water, we expect to fall between 18-22%. To grasp this standard, it is usually recommended that the ratio of coffee to water is 1:15. Of course, this number is quite flexible. We often adjust the ratio of coffee to water according to individual taste, water temperature, degree of grinding and degree of roasting. After many fine-tuning, we find out the most appropriate ratio of coffee to water that suits our own taste.

two。 Grinding thickness and extraction time: we can make an observation that when we go to the stream to play in the water, it is not easy to soak a pile of pebbles when the water is spilled on the pebbles; on the contrary, when we go to the seaside to play in the water, some water can wet a pool of sand. When we apply this physical phenomenon to coffee, it is not difficult to imagine how important the degree of grinding is to coffee extraction. The coarse degree of grinding takes a long time to soak the coffee flavor into the water and extract it by soaking. For example, pressure and siphon are ideal for coarse ground coffee, because the contact surface between coffee and water is small. So let the water pass too quickly, it is difficult for coffee to have proper contact time with the water to dissolve the taste into the water. On the other hand, the use of finely ground coffee will save time for coffee to come into contact with water. If you use the way of soaking, there will be excessive extraction. So we usually use a method that allows water to come into contact with coffee quickly and flow out quickly. Such as hand flushing or concentrated extraction. How much should the degree of grinding be adjusted? Because everyone uses different equipment, it is not fair to say which bean grinder or coffee machine is more standard. It is suggested that the thickness should be adjusted according to the extraction method and personal taste. After all, what everyone likes is different, so many exceptions will happen. It is like the Turkish method of cooking very fine ground coffee and a small amount of water on the stove, which is very different from the principle we have mentioned above, but we cannot reject the Turkish method of extraction because of this. After all, Turkish coffee has a beautiful side of Turkish coffee, just from a different point of view.

3. Appropriate extraction operation according to the condition of coffee, we often use the following three techniques to adjust 1 to estimate the grinding degree of coffee and the time it takes to come into contact with water. As mentioned in the previous paragraph, the cooking methods suitable for rough grinding and fine grinding are different, and a little carelessness may lead to insufficient or over-extraction. two。 The temperature of water. The higher temperature will shorten the extraction time, while the lower temperature we need to extend the extraction time to obtain the ideal extraction degree. In terms of water temperature, we usually recommend falling between 91 and 94 degrees Celsius, in other words, boiling water is not an ideal choice for coffee extraction, because too high temperature will seriously shorten the extraction time, so excessive extraction often occurs, resulting in reduced aroma, poor flavor, and heavy taste due to over-extraction. 3. Turbulence. In order to make the coffee soak evenly, we often wet the coffee first, let the water flow through the coffee once, tidy up the contact surface between the coffee and water, and then formally extract it. We often use this technique when using hand pots, and some people call it "steaming". Similarly, when we use siphon, we also use this technique to smooth the interface between water and coffee in order to achieve the purpose of balanced extraction.

4. The ideal extraction method is roughly divided into six different extraction methods according to the way the equipment is used:

i. Immersion: nothing is more representative than French pressure. Let the coffee soak in hot water for a period of time and then filter out.

ii. How to cook: people who often watch westerns may have seen the heroine put coffee and water in a pot and cook it directly on the stove in "Once Upom A Time In The West". The coffee infiltration method is extracted by slow heating and hot convection extraction in water: the principle of the mocha pot is the infiltration method. Heat the hot water vapor into the metal tube on the stove, spread the smooth coffee in the filter, and finally the extracted coffee liquid flows out from the outlet of the upper pot.

iv. Drip filter: both hand-made and American coffee machines belong to this method, which drips hot water into coffee and uses the physical nature of the water to extract coffee from top to bottom.

v. Vacuum filtration: Syphon is the most representative tool for this kind of extraction. Use the siphon principle to suck the hot water from the lower pot into the upper pot, cool the lower pot after the extraction is completed, and then suck the water back into the lower pot by way of extraction.

vi. Pressure injection: Espresso is representative of this method. Using the pressure generated by the machine, let the water pour into the coffee instantly to extract the most essential part of the coffee.

Each of the above methods has its advantages and disadvantages. There is no perfect extraction method in the world, but as long as we grasp the principles of extraction and correct operation, we can avoid a lot of mistakes.

5. Good water quality. The ratio of water to coffee is 1:15. After deducting the solid part, water accounts for 98% of a cup of coffee! So we can say that the quality of water affects 98% of coffee. In addition to pure water, there are many kinds of minerals and, of course, some microbes in the water we use. Because coffee is very sensitive, too much or too little minerals will affect the taste of coffee. If there are too many minerals, it can even damage our equipment (especially Espresso Machine, calcium is the killer of machines). Therefore, it is very important for us to soften and filter the water quality. Taiwan's tap water quality is not good, high chlorine content, biological impurities (microorganisms, organic matter, bacteria …...) It is not low, although it is much better than India, but we all know that the quality of raw water is poor and can not be drunk raw, and the taste of boiled water is not very good. Of course, this kind of water-extracted coffee will not taste any better. But if it is filtered and softened, the situation can be greatly improved.

6. After the appropriate filter medium, we must remove the turnips and store the turnips through the filter to filter out the extracted coffee in order to get a cup of coffee with better taste. According to the material, we have the following four different filter media.

a. Metal filter, filter cup: take out the Portfilter of Espresso, and we can all find a small metal basin covered with small holes. We usually put coffee in this small basin for extraction, and the extracted coffee liquid leaks out of the small hole. The biggest advantage of this method is that the filter cup is a permanent commodity, normal use is not easy to damage, and the disadvantage is the need for careful cleaning, otherwise the residue and oil stains will affect the next use.

b. Mesh filter: when you turn on the American coffee machine, the factory usually gives away a nylon mesh filter. We use nylon or metal woven mesh to filter the coffee. The advantage of this kind of filtration is that the outlet of the water is many and dense, which can make the water rush through the coffee quickly and flow out smoothly, but the disadvantage is that it is easy to bring out the fine powder of coffee, resulting in the turbidity of the coffee extract.

c. Filter cloth: just like traditional Chinese medicine brine bags and tofu cloth, the pores woven by cloth fibers are more and denser than metal mesh or nylon mesh, and the cloth is somewhat absorbent and can contain some water. keep the water from flowing out of the coffee too fast to avoid over-extraction. But because the furnishings are easy to absorb the taste, they should be washed once at a time, and must be boiled in hot water in order to remove the residual flavor of most of the last batch of coffee. And the filter cloth is not a permanent commodity and will be replaced over a period of time.

d. Filter paper: I believe everyone has the experience of putting filter paper in coffee machine, whether it is American bucket or funnel-shaped, filter paper can be said to be the most efficient and convenient filtering method (no wonder American coffee machines are used in offices). However, there are many disadvantages of filter paper, which is not only not environmentally friendly, but also affects the quality of extracted coffee because of the bleached filter paper flavor. Therefore, most boutique coffee is not recommended to use filter paper as a filter medium.

As long as you master the above six basic conditions, I believe everyone can use simple equipment at hand to make quality coffee!