Decaffeination
Decaffeination is the removal of caffeine from coffee beans, cocoa, tea leaves, and other caffeine-containing materials.
To ensure product quality, manufacturers are required to test the newly decaffeinated coffee beans to make sure that caffeine concentration is relatively low.
[3] Though Runge was able to isolate the compound, he did not learn much about the chemistry of caffeine itself, nor did he seek to use the process commercially to produce decaffeinated coffee.
These methods take place prior to roasting and may use organic solvents such as dichloromethane or ethyl acetate, supercritical CO2, or water to extract caffeine from the beans, while leaving flavour precursors in as close to their original state as possible.
[5][6] The process was patented in 1906, and involved steaming coffee beans with various acids or bases, then using benzene as a solvent to remove the caffeine.
However, because of health concerns regarding benzene (which is recognized today as a carcinogen),[9] other solvents, such as dichloromethane or ethyl acetate, are now used.
[10] The unroasted (green) beans are first steamed and then rinsed with the solvent which extracts the caffeine, while leaving other constituents largely unaffected.
The newly caffeine-rich GCE solution is then passed through the activated carbon filters to remove the caffeine again, and the process is repeated.
Developed by Kurt Zosel, a scientist of the Max Planck Institute, it uses CO2 (carbon dioxide), heated and pressurised above its critical point, to extract caffeine.
Caffeine dissolves into the CO2; but compounds contributing to the flavour of the brewed coffee are largely insoluble in CO2 and remain in the bean.
[4][18] To ensure product quality, manufacturers are required to test the newly decaffeinated coffee beans to make sure that caffeine concentration is relatively low.
[26] The prospect for Decaffito-type coffees was shown by the discovery of the naturally caffeine-free Coffea charrieriana variety, reported in 2004.
Temperatures of 100 °C or more, moderate extraction time of 3 minutes, and a 1:20 leaf to water weight per volume[clarification needed] ratio removed 83% caffeine content and preserved 95% of total catechins.
[31] Catechins, a type of flavanol, contribute to the flavor of the tea and have been shown to increase the suppression of mutagens that may lead to cancer.
[34] Certain processes during normal production might help to decrease the caffeine content directly, or simply lower the rate at which it is released throughout each infusion.
In China, this is evident in many cooked pu-erh teas, as well as more heavily fired Wuyi Mountain oolongs; commonly referred to as 'zhonghuo' (mid-fired) or 'zuhuo' (high-fired).
