How to use the filter of the cold extract coffee maker? How to filter the coffee grounds clean?

Experienced friends know that there are many factors that affect the taste of cold extracted coffee. Among them, the most influential ones are the choice of coffee beans, grinding degree, powder and water ratio, and soaking time. Secondly, there are some small production skills, such as full stirring, ensuring that the container is clean, water quality, etc., which will more or less change the final taste of coffee.

But in fact, there is another detail that has also attracted the attention of many friends: obviously using the parameters provided by Qian Jie in the tutorial, but there will always be a layer of oil floating on the cold extract he made, so he wondered if the coffee is broken, or it is caused by the fact that the appliance is not cleaned clean.

Before finding out the reason, Qianjie thought it necessary to first find out what the "oil" on the coffee was.

Many people know that freshly made espresso brings a dense Crema, which is both the source of coffee aroma and a symbol of the freshness of coffee beans. In terms of composition, Crema is a manifestation of carbon dioxide wrapped in oil. It mainly comes from the water-soluble fat in the body of coffee beans. When the foam group completely dissipates, we can see a layer of floating matter on the coffee liquor, and this is Real coffee grease.

In fact, coffee grease can also be found in other normal pressure extractions. For example, when we use a French press pot to extract medium and deep-roasted coffee, due to the large gap in the metal filter, the grease will take the opportunity to penetrate out, allowing the coffee The surface of the liquid has a layer of "oily shine", and some very fine powders will also run into the water, making it particularly "turbid" to drink.

As for cold extraction, although the entire process is soaked in a low-temperature environment, the water-soluble fat in the coffee will still be released into the coffee like hot extraction, but at a slow rate, and the speckled oily shine is the expression of the coffee fat after condensation.

Compared with other extraction methods, cold extraction can be said to have few requirements on containers. It can be a special cold extraction pot, a clean sealed pot at home, or a drink bottle that is drunk and cleaned. In short, as long as it is sanitary and has no odor, and a closed container that ensures that it is isolated from external gases can serve as a "cold extraction pot."

Similarly, there are many options for tools for filtering coffee grounds, such as the built-in filter, metal filter cups, hand-flushed filter paper, flannel, and the mesh surface of the ear inner bag are all commonly used by everyone. Filter equipment. Different materials, different filter holes have different structures and sizes, and the particulate matter that can effectively block them is naturally different. If you want to remove the condensed oil on coffee, you must choose an appliance with better filtering performance.

Qianjie found that some friends felt that filtering was too troublesome, so for convenience, they poured out the upper half of the coffee liquor and drank it directly after the cold extract was soaked. In fact, this practice would cause the coffee to carry a large amount of condensed oil. Not only the taste was dull, but the texture was still rustle when it was drunk, and it was accompanied by many dusty floating particles, so the taste was generally not too good.

For example, the cold extraction pot often used in Qianjie stores has a built-in filter hole of 300 mesh, which belongs to the category with high fineness. When it is used in the street to soak fruity coffee beans and tomatoes, due to the shallow baking, a finer degree of grinding will be used (the screening rate of China's No. 20 powder sieve is 80%), corresponding to the EK43s bean grinder scale of 9.5 grids/the C40 bean grinder scale of 22 grids.

When the filter element is removed after the 10-hour extraction is over, the poured coffee liquor also has a lot of very fine powder remaining in it. If it is not filtered again, not only will there be a layer of oily luster floating on the liquid surface, but the coffee will have an obvious rough feeling. After drinking, there is even powder residue visible to the naked eye.

Therefore, in order to make the taste of cold extraction better, Qianjie will use the best filtering filter paper to "sift" the coffee again to remove most of the condensed oil and very fine powder particles; at the same time, the filtered cold extraction coffee will be placed in the refrigerator again, sealed and refrigerated for 3 to 4 hours, and the flavor substances will be further precipitated and fermented. This will make the juice of cold extraction of small tomatoes feel fuller and more acidic.

In addition to filtering, the cleaning of instruments cannot be ignored. Many friends don't spend too much time cleaning the cold extraction pot after using it, but simply flush it with tap water. Over time, the condensed coffee oil will stick to the filter screen, forming a "oil-consuming smell." If the frequency of use is high, Qianjie recommends taking it apart regularly and carefully brushing it with a cleaner to not only remove residual oil, but also avoid aging of the filter.

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