caffeine
adenine guanine
Caffeine is the world's most widely consumed psychoactive substances, but unlike many others, it is legal and unregulated in nearly all parts of the world. Caffeine is classified as "generally recognized as safe" (GRAS) with toxic doses, over 10 grams per day for an adult. A cup of coffee contains 100–200 mg of caffeine.
Caffeine can have both positive and negative health effects. It may confer a modest protective effect against some diseases, including Parkinson's disease and cardiovascular disease such as coronary artery disease and stroke. On the other hand, caffeine can cause sleep disruption, headaches, irritability, increased blood pressure and heart rate.
Decaffeination (decaf) is applied to remove caffeine from coffee beans, cocoa, tea leaves and other caffeine-containing materials. Decaffeinated drinks contain typically 1–2% of the original caffeine content, and sometimes as much as 20%.
In all decaffeination processes, coffee is always decaffeinated in its green, unroasted state. The greatest challenge to the decaffeination process is to try to separate only the caffeine from the coffee beans while leaving the other chemicals such as sucrose, cellulose, proteins, citric acid, tartaric acid, and formic acid at their original concentrations. Since caffeine is a polar, water-soluble substance, water is used in all forms of decaffeination. However, water alone is not the best solution for decaffeination because it is not a selective solvent and therefore removes other soluble substances, including sugars and proteins, as well as caffeine. Therefore decaffeination processes use a decaffeinating agent such as methylene chloride, activated charcoal, CO2, or ethyl acetate.
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