The extraction principle of hand-made Coffee and the changes of dissolution, extraction and Filtration

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What process does it take to bring the mellow coffee out of the coffee beans? We know each other by hand brewing coffee.

This paper gives a brief introduction to different roasted coffee beans and grinding.

Question:

1. Before making coffee, you should grind the coffee beans into powder. Isn't it good to flush the coffee beans directly? What kind of scientific principle is this?

two。 Why do you need to steam and wait when transparent and colorless hot boiled water rushes into the filter paper containing coffee powder?

3. Why does the liquid from the filter paper turn brown?

4 Why is it recommended that light-roasted coffee use a metal filter instead of filter paper? Does it have something to do with particle size?

5. Is the coffee powder "dissolved" in water? Why is it that the longer you soak, the more bitter the coffee tastes?

Dissolution, extraction and filtration

To know the coffee we are familiar with, we must first have an understanding of dissolution, extraction and filtration.

The principle of separating substances is to separate different pure substances from the mixture, and pure substances can often be separated by various physical methods with the help of the unique properties of various pure substances. Dissolution is the phenomenon that one substance (solute) is uniformly dispersed into another substance (solvent), while extraction is to separate the liquid components from the mixture by different solubility of the solvent. Dissolution is a phenomenon, while extraction is a mixture separation technique.

Junior high school teaching refers to the dissolution filtration method: using filter paper to separate the mixture of liquids and insoluble solids with different degrees of dissolution. The solid particles are large and cannot pass through the filter paper; the particles of water or solution are small and can pass through the small holes in the filter paper. Coffee is extracted and filtered. The special substances in the coffee beans are dissolved by hot water, and then the coffee grounds are filtered out. Generally speaking, the quality of coffee is affected by extraction temperature and filtration time. The higher the extraction temperature and the longer the extraction time, the more bitter the coffee.

When making coffee by hand, the filter cup is also one of the keys to affect the flavor. The shape, the number and size of the outlet hole affect the time of coffee liquid outflow. Some Japanese-style slow flushing techniques have only one hole, the flow rate is slow, and the coffee is rich.

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