Coffee review

Coffee beans have lower caffeine after cold extraction. How do you make cold coffee?

Published: 2024-11-03 Author: World Gafei
Last Updated: 2024/11/03, For more information on coffee beans, please follow the coffee workshop (Wechat official account cafe_style) caffeine is a water-soluble substance, usually in the form of uncrystallized water or in the form of a crystalline water. Pure caffeine is white powder or white needle-like crystal, odorless, bitter taste. It is mentioned in Mr. Han Huaizong's Coffee Science that Robusta

Professional coffee knowledge exchange more coffee bean information please follow the coffee workshop (Wechat official account cafe_style)

Caffeine is a water-soluble substance, usually in the form of non-crystalline water or a crystalline water. Pure caffeine is white powder or white needle-like crystal, odorless, bitter taste.

Mr. Han Huaizong mentioned in his book Coffee Science that the caffeine content of coffee beans grown in Robusta is about 2% of the weight and is about twice that of Arabica.

In terms of R beans, the caffeine content of 100g Luobu beans is 2g (2%). When 0 ℃ and 100ml ice water coexist, the caffeine extracted is relatively low (only 0.6 g can be extracted). However, we have mentioned before that 100g beans will not only use 100ml water (that is, 1:1 ratio extraction), at least 1:10 ratio will be used, even if 100g Luo Bean is used to make cold-extracted coffee with 0 ℃, 1000ml ice water, all caffeine will be precipitated, so the caffeine in cold-extracted coffee will not become less because of low extraction temperature. And the caffeine content here is calculated in terms of raw beans, which have more caffeine than roasted beans, that is, roasted beans will have less caffeine, and the deeper the roast, the less caffeine in the beans.

In general, substances in daily life have three changes: gaseous state, liquid state (molten state) and solid state. The three-state change of water can be observed at one atmospheric pressure, but caffeine is only solid and gaseous, not melted, because caffeine sublimates from powdery or acicular solid to gas at 178℃. Coffee is roasted at temperatures above 190 ℃, so the theory of deeper roasting and less caffeine is based on this.

Friends who play baking beans by themselves will notice that after baking for a period of time, there will be crystals like cotton, yellow or white in the smoke pipe or around the smoke outlet of the bean dryer. caffeine is sublimated from the internal heat of the coffee beans. caffeine crystals condensed again as expected (below the sublimation point).

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