What details should I pay attention to when making cold extract? What is the correct grinding degree of coffee powder for cold brewed coffee? How long does it take to soak?

With the pace of summer, Qianjie also ushered in another peak season for drinking iced coffee. If you don't want to go out and want to cheer up in this sleepy afternoon, it's perfect to make a refreshing cup of cold coffee at home.

Different from the usual hot water brewing coffee, the so-called cold extraction is mainly the use of cold water (normal temperature water) and coffee powder mixture, sit in a low temperature environment for several hours, and finally filter out the powder to get the iced coffee liquid. A bag of coffee, a sealed clean container, water and a refrigerator can achieve cold extraction freedom at home.

In fact, compared with the rigorous parameters of other extraction methods, the compatibility of cold extraction is very high, from the selection of coffee beans to sealed containers, to the ratio of powder to water, grinding thickness and soaking time, it has a large controllable range. In other words, you can make iced coffee that tastes good as long as you don't use a particularly extreme combination of parameters.

But there are small partners in the attempt but encountered problems: obviously using the same coffee beans, the parameters are also "copied", the cold extract is not as sweet as the store to drink, this is why? Here Qianjie summed up several key details, home friends might as well check themselves to see if the problem comes from here.

1. The soaking time should not be less than 8 hours and more than 18 hours

In hand flushing, we will pay special attention to water temperature and time. Because water is the main medium for brewing, the temperature directly affects the extraction efficiency of coffee, too high or too low will change the taste of coffee; similarly, too long time is easy to extract, short extraction may not be enough. Because the cold extraction is only in contact with the low temperature water of 4-10 °C, the extraction efficiency is very slow, so it is necessary to extend the soaking time to release more aroma substances, so that sugars and organic acids and other compounds can be dissolved more fully. The resulting coffee is also more balanced in terms of acidity, sweetness and alcohol thickness. In general, the soaking time of cold-extracted coffee is usually recommended to be controlled at 8-18 hours.

Qianjie once did a cold extraction experiment with time as a variable, in which the same amount of butterfly coffee was ground and soaked for 4 hours, 10 hours, 16 hours and 24 hours respectively. Finally, it was found that the 4-hour coffee had almost no aroma, the taste was light and watery; the cold extraction entrance after soaking for 24 hours was slightly bitter and showed signs of extraction; the flavor of the 10-hour and 16-hour groups were the best, the former was more refreshing and the latter was more full-bodied.

If you are worried that you do not remember the time, you can also refer to the practice of "lazybones" in Qianjie. Soaking begins at 7: 9 o'clock the night before, and it is also filtered and separated at 7: 9 o'clock the next morning, so that the time will be kept within the conservative range of 10 to 14 hours.

two。 Too fresh coffee beans can also affect extraction.

In many forms of high-temperature cooking, fresh baking is often the first consideration for many people, because the bean aroma that is not in the appreciation period will be greatly reduced, which is a consensus for a long time. Secondly, the discharge of gas allows us to directly judge whether the coffee beans are fresh or not, such as Italian concentrated oil, bulging when steaming, etc., and it also shows that the coffee is in the peak stage of aroma.

Coffee beans are constantly heated in the boiler, and freshly roasted beans contain a lot of carbon dioxide. If you want to extract the aromatic compounds inside, you have to let them out first. Cold extraction itself is a relatively static extraction state, and low temperature water inhibits the release of this gas to a certain extent. It is conceivable that the coffee brewed with "fresh beans" is prone to insufficient extraction. If we are not in a hurry to drink, Qianjie thinks it is best to soak coffee with a roasting date of more than 10 days, which is more beneficial for us to make a cold extract with rich aroma.

3. Stir fully before and after extraction

Many new friends quickly, after adding water directly sealed into the refrigerator, the surface of the coffee powder seems to be wet, but in fact some parts of the place is not exposed to water, then the dry part of the coffee obviously did not participate in the extraction. In addition, after a night of rest, most of the particulate matter sank at the bottom of the container, so if you pour it out and filter it directly, there is a good chance that you will only get a light-colored liquid on the top layer, which probably won't taste too good. Therefore, the action of "stirring" must be added when making cold extract.

According to previous street experience, if you use a pot with a large capacity, you can stir the coffee powder and water with a mixing rod or a long spoon before extraction, and then put it in the refrigerator. After taking it out, stir it several times and then filter it. When you use a sealed water bottle, just shake it up and down gently after the lid.

4. Filter the powder thoroughly and make it taste better.

There are many options for filtering coffee dregs, such as built-in filter, metal filter, filter paper, flannel filter and so on. If the size of the filter pore structure is different, the particulate matter that can effectively block is also different. Take the cold extraction kettle used in Qianjie as an example, the size of the screen hole is 245 mesh, and the fineness is relatively high, but there is still the precipitation of fine powder and ultra-fine powder. At this time, if it is not filtered again, the liquid surface will float with a layer of flocculent oil. The flavor of the coffee is not much different from that after filtration, but the rough feeling left on the tongue when swallowing will be obvious, and there will be some visible powder residue at the bottom of the cup.

In order to have a better drinking experience, Qianjie will be screened with a higher density filter paper, which can not only effectively filter out the very fine powder, but also block more than 80% of the condensed grease. After separating the powder, Qianjie will put the cold-extracted coffee liquid in the refrigerator and refrigerate for 3-4 hours, waiting for the flavor to further precipitate. In this way, the taste of cold extract is very full, the taste is clearer and the acidity is more transparent.

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