Why does Xiao Wang in the office never suffer from insomnia after drinking coffee?

Want to be energetic all day? A cup of strong coffee is a must for workers in the morning!

But if a cup of coffee comes with afternoon tea, many friends may "look up at the sky and have no sleepiness" at night.

Image source: hippopx

In order to meet everyone's different needs for caffeine, decaffeinated coffee has become popular.

In the United States, the guideline for decaffeinated coffee is that 97% of the caffeine in each green coffee bean must be removed, while the international standard is that the caffeine content in each decaffeinated green coffee bean can be only 0.1%.

Even with such high difficulty, many businesses have still achieved decaf coffee through scientific means.

1

Swiss Wash

The Swiss washed method removes 99% of the caffeine in coffee beans without the use of chemical solvents.

The operation process can be roughly divided into three stages.

Image source: hippopx

First, a large amount of green coffee beans are washed and soaked to remove the soluble substances in the coffee beans. Then the coffee beans are taken out and the caffeine in the solution is filtered out through an activated carbon filter, thereby obtaining a caffeine-free solution.

In the second stage, new coffee beans that have been pre-soaked are poured into the caffeine-free solution extracted in the first stage. Under a certain time, temperature and flow rate, caffeine is continuously dissolved from the new coffee beans, and the soluble substances in the caffeine-free solution reach equilibrium. The solution in the container is then passed through a special activated carbon filtration system to filter out 99.9% of the caffeine. This step is called "decaffeination", and the flavor of the coffee is retained.

In the third stage, you only need to take out the coffee beans from the solution, dry them in the sun or dry them, and then they can be used to make coffee.

The advantage of the Swiss water washed method is that it does not require any chemical solvents to assist, and the flavor of the coffee is retained to the greatest extent. However, since the caffeine extracted is directly filtered out and cannot be used for other purposes, the cost is high.

2

Dichloromethane extraction method

The dichloromethane extraction method first soaks the coffee beans in boiling water for several hours. At this time, the caffeine and other flavor substances in the coffee beans will be stripped out. Then the coffee beans are taken out, and chemicals such as dichloromethane or ethyl acetate are added to the water. The caffeine is extracted through the solvent and then heated and evaporated. The remaining water is chemically poured into the coffee beans to obtain decaffeinated coffee.

This method is very popular in Europe, but it is not common in China. Since this extraction method uses organic solvents containing chemical drug ingredients to extract caffeine, excessive drinking will cause certain harm to the body.

3

Supercritical Carbon Dioxide Extraction Technology

At normal temperature and pressure, carbon dioxide is a gas. At low temperatures, carbon dioxide turns into dry ice. When the temperature and pressure exceed a certain value, carbon dioxide will enter a supercritical state, and the carbon dioxide under high pressure will become a "supercritical flow".

Supercritical carbon dioxide has a magical property: it can dissolve substances that are difficult to dissolve normally. Based on this property, supercritical carbon dioxide extraction technology is applied to the extraction of caffeine.

The specific process of removing caffeine using supercritical carbon dioxide extraction technology is as follows: first soak the green coffee beans in hot water, wait until the water content of the coffee beans reaches 50%, then pour them into a container with huge pressure, then apply 250-300 atmospheres of pressure to the coffee beans, and at the same time inject supercritical carbon dioxide into the coffee beans to dissolve the caffeine.

In the supercritical state, as long as the temperature and pressure are adjusted, carbon dioxide can be extracted to different degrees according to the characteristics of the molecules, so there is no need to worry about the unique aroma molecules of coffee being taken away.

Next, the mixture of supercritical carbon dioxide and caffeine is filtered into another large vat, and the pressure is reduced. The carbon dioxide then returns to a gaseous state and evaporates, leaving only the caffeine. The stripped coffee is then removed to extract decaffeinated coffee.

Image source: hippopx

Compared with the above two extraction methods, supercritical carbon dioxide extraction technology is efficient and environmentally friendly, and can retain the flavor of coffee beans to the greatest extent. It is currently one of the mainstream methods for removing caffeine. Not only coffee beans, but also tea leaves and cocoa beans are de-caffeinated using this method.

Coffee is actually the largest source of antioxidants in the Western diet. Decaf and regular coffee have similar antioxidants, though the antioxidant content may be 15% lower. In addition to antioxidants, decaf coffee also contains several nutrients. A cup of brewed decaf coffee provides potent minerals as well as vitamin B3, among others.

Whether it is normal coffee or decaf coffee, there is no essential distinction between good and bad. If you want to be energetic, have a cup of original American coffee. If you want to enjoy the taste of coffee but don’t want to make your nerves too excited, decaf coffee is a good choice!

Let's talk about it

After a cup of coffee in the afternoon, are you unable to sleep at night like Tadpole?

Have you ever tried decaf or decaf coffee? What brands are they and do they taste as good as regular coffee?

Come and communicate, recommend things to each other or try them out!

END

Review expert: Wang Guoyi, postdoctoral fellow in nutrition and food safety at China Agricultural University.

Tadpole's original work, please indicate the source when reprinting

Editor/Xiao Xitushuo