question: How to they remove the caffeine from tea and coffee?
comment: One way is using liquid carbon dioxide to dissolve the caffeine away while leaving the flavored compounds mostly alone. Another way is to wash the product in a saturated mixture of the coffee or tea from which the caffeine has been removed from using things like charcoal filters. As there is now no caffeine in the fluid but there is in the product, it tends to seep out into the fluid to equalize while the original flavoring compounds stay in.
passages: Caffeine can also be extracted from coffee beans and tea leaves using a direct organic extraction. The beans or leaves can be soaked in ethyl acetate which favorably dissolves the caffeine, leaving a majority of the coffee or tea flavor remaining in the initial sample.
  
  Section::::Techniques.:Multistage countercurrent continuous processes.
   BULLET::::- Water extraction: Coffee beans are soaked in water. The water, which contains many other compounds in addition to caffeine and contributes to the flavor of coffee, is then passed through activated charcoal, which removes the caffeine. The water can then be put back with the beans and evaporated dry, leaving decaffeinated coffee with its original flavor. Coffee manufacturers recover the caffeine and resell it for use in soft drinks and over-the-counter caffeine tablets.
   A decaffeination process removes caffeine from coffee beans to lower their caffeine content. Four main methods are used to extract caffeine from coffee beans:
  
  BULLET::::- The so-called "Swiss" water method, so called from allegedly having been developed in Switzerland, where the beans are soaked in water;
  
  BULLET::::- the ethyl acetate method, where the beans are washed in a solution of water and ethyl acetate;
  
  BULLET::::- the carbon dioxide method, where either liquid or "supercritical" (between liquid and gas) carbon dioxide is applied to the beans at high pressure; or
   The water is normally kept at room temperature, but chilled water is also used. The grounds are filtered out of the water after they have been steeped using a paper coffee filter, a fine metal sieve, a French press, or felt, in the case of the "Toddy" brewing system. The result is a coffee concentrate that is diluted with water or milk, and is served hot, over ice, or blended with ice and other ingredients such as chocolate. 
   Decaffeination of coffee seeds is done while the seeds are still green. Many methods can remove caffeine from coffee, but all involve either soaking the green seeds in hot water (often called the "Swiss water process") or steaming them, then using a solvent to dissolve caffeine-containing oils. Decaffeination is often done by processing companies, and the extracted caffeine is usually sold to the pharmaceutical industry.
  
  Section::::Processing.:Storage.
   BULLET::::- Supercritical carbon dioxide extraction: Supercritical carbon dioxide is an excellent nonpolar solvent for caffeine, and is safer than the organic solvents that are otherwise used. The extraction process is simple: is forced through the green coffee beans at temperatures above 31.1 °C and pressures above 73 atm. Under these conditions, is in a "supercritical" state: It has gaslike properties that allow it to penetrate deep into the beans but also liquid-like properties that dissolve 97–99% of the caffeine. The caffeine-laden is then sprayed with high-pressure water to remove the caffeine. The caffeine can then be isolated by charcoal adsorption (as above) or by distillation, recrystallization, or reverse osmosis.
   Another commonly used method is solvent extraction, typically using oil (extracted from roasted coffee) or ethyl acetate as a solvent. In this process, solvent is added to moistened green coffee beans to extract most of the caffeine from the beans. After the beans are removed from the solvent, they are steam-stripped to remove any residual solvent. The caffeine is then recovered from the solvent, and the solvent is re-used. The Swiss Water Process is also used for decaffeination. Decaffeinated coffee beans have a residual caffeine content of about 0.1% on a dry basis. Not all facilities have decaffeination operations, and decaffeinated green coffee beans are purchased by many facilities that produce decaffeinated coffee.
   BULLET::::- Extraction by organic solvents: Certain organic solvents such as ethyl acetate present much less health and environmental hazard than chlorinated and aromatic organic solvents used formerly. Another method is to use triglyceride oils obtained from spent coffee grounds.
  
  "Decaffeinated" coffees do in fact contain caffeine in many cases – some commercially available decaffeinated coffee products contain considerable levels. One study found that decaffeinated coffee contained 10 mg of caffeine per cup, compared to approximately 85 mg of caffeine per cup for regular coffee.
  
  Section::::Chemistry.:Detection in body fluids.
   Green coffee beans are soaked in a hot water/coffee solution to draw the caffeine to the surface of the beans. Next, the beans are transferred to another container and immersed in coffee oils that were obtained from spent coffee grounds and left to soak.
  
  After several hours of high temperatures, the triglycerides in the oils remove the caffeine, but not the flavor elements, from the beans. The beans are separated from the oils and dried. The caffeine is removed from the oils, which are reused to decaffeinate another batch of beans. This is a direct-contact method of decaffeination.
  
  Section::::Decaffeinated coffee.
   One U.S. company is marketing oral dissolvable caffeine strips. Another intake route is SpazzStick, a caffeinated lip balm. Alert Energy Caffeine Gum was introduced in the United States in 2013, but was voluntarily withdrawn after an announcement of an investigation by the FDA of the health effects of added caffeine in foods.
  
  Section::::Products.:Inhalants.
   Section::::Expansion of the product line.:Decaffeinated coffee.
   In addition to CO process extraction, tea may be also decaffeinated using a hot water treatment. Optimal conditions are met by controlling water temperature, extraction time, and ratio of leaf to water, where higher temperatures at or over 100 °C, moderate extraction time of 3 minutes, and a 1:20 water to leaf weight per volume ratio removed 83% caffeine content and preserved 95% of total catechins. Catechins, a type of flavanols, contribute to the flavor of the tea and have been shown to increase the suppression of mutagens that may lead to cancer.
   In the direct organic solvent process, unroasted (green) beans are first steamed and then rinsed with a solvent (e.g. methylene dichloride or ethyl acetate). The solvent extracts the caffeine while leaving other constituents largely unaffected. The process is repeated from 8 to 12 times until the caffeine content meets the required standard (97% of caffeine removed according to the US standard, or 99.9% caffeine-free by mass per the EU standard). 
  
  Section::::Decaffeination processes for coffee.:Organic solvent processes.:Indirect method.
   In the indirect method, beans are first soaked in hot water for several hours, in essence making a strong pot of coffee. Then the beans are removed and either dichloromethane or ethyl acetate is used to extract the caffeine from the water. As in other methods, the caffeine can then be separated from the organic solvent by simple evaporation. The same water is recycled through this two-step process with new batches of beans. An equilibrium is reached after several cycles, wherein the water and the beans have a similar composition except for the caffeine. After this point, the caffeine is the only material removed from the beans, so no coffee strength or other flavorings are lost. Because water is used in the initial phase of this process, indirect method decaffeination is sometimes referred to as "water-processed".
   In the case of coffee, various methods can be used for decaffeination. These methods take place prior to roasting and may use organic solvents such as methylene dichloride or ethyl acetate, supercritical CO, or water to extract caffeine from the beans while leaving flavour precursors in as close to their original state as possible.
  
  Section::::Decaffeination processes for coffee.:Organic solvent processes.
  
  Section::::Decaffeination processes for coffee.:Organic solvent processes.:Direct method.
   Carbon dioxide is gaining popularity among coffee manufacturers looking to move away from classic decaffeinating solvents, because of real or perceived dangers related to their use in food preparation. s is forced through the green coffee beans which are then sprayed with water at high pressure to remove the caffeine. The caffeine can then be isolated for resale (e.g. to the pharmaceutical or beverage manufacturers) by passing the water through activated charcoal filters or by distillation, crystallization or reverse osmosis. Supercritical carbon dioxide is used to remove organochloride pesticides and metals from agricultural crops without adulterating the desired constituents from the plant matter in the herbal supplement industry.
   CBTL, a single-serve system for home use, was launched in the United States, Singapore, Malaysia, South Korea, and the Philippines in 2010. Several types of single-serve capsules are available for the machines: espresso, coffee, tea, and hot chocolate.
  
  Section::::Products.:Kosher and halal.
   Caffeine may be synthesized in the lab starting with dimethylurea and malonic acid.
  
  Commercial supplies of caffeine are not usually manufactured synthetically because the chemical is readily available as a byproduct of decaffeination.
  
  Section::::Chemistry.:Decaffeination.
  
  Extraction of caffeine from coffee, to produce caffeine and decaffeinated coffee, can be performed using a number of solvents. Benzene, chloroform, trichloroethylene, and dichloromethane have all been used over the years but for reasons of safety, environmental impact, cost, and flavor, they have been superseded by the following main methods:
   As part of the Lipton study in South Carolina, an out-station was established in Fairhope, Alabama as well as other select locations in the Southern US. The material in Fairhope was destroyed by a hurricane not long after its inception and was abandoned. However, the out-station supervisor rescued a few seeds and cuttings which were used to start a private plantation nearby now known as the Fairhope Tea Plantation, owned by Donnie Barratt, the son of the out-station supervisor. Tea is still produced at the plantation in small quantities, sold through a nearby gift shop.
  
  Section::::Hawaii.
   In the case of decaffeinated coffee, eliminating caffeine can cause a sharp decline in the natural taste of the coffee bean. During the process of decaffeination, the largest coffee producers in the world use a variety of ways to remove caffeine from coffee, often by means of chemical manipulation and the use of potentially harmful chemical components, such as methylene chloride or ethyl acetate. One process that does not use solvents is the patented Swiss Water Process, which relies on soaking beans in a bath which is essentially brewed coffee from unroasted green beans. The caffeine permeates into the bath at a much higher rate than most of the flavor elements. While the process is certified organic, the water solubility of coffee flavor compounds assures that some of the coffee flavor is lost or changed by the bath. The process is more costly than solvent methods, and is performed commercially by only one plant in British Columbia, Canada. Therefore, only a small percentage of decaffeinated coffee available on the market uses this method.
   The PEG–NaCl system has been shown to be effective at partitioning small molecules, such as peptides and nucleic acids. These compounds are often flavorants or odorants. The system could then be used by the food industry to isolate or eliminate particular flavors. Caffeine extraction used to be done using liquid–liquid extraction, specifically direct and indirect liquid–liquid extraction (Swiss Water Method), but has since moved towards super-critical CO as it is cheaper and can be done on a commercial scale.
  
  Section::::Techniques.:Ion pair extraction.:Analytical chemistry.
   Another process, known as the Swiss Water Method, uses solely water and osmosis to decaffeinate beans. The use of water as the solvent to decaffeinate coffee was originally pioneered in Switzerland in 1933 and developed as a commercially viable method of decaffeination by Coffex S.A. in 1980. In 1988, the Swiss Water Method was introduced by The Swiss Water Decaffeinated Coffee Company of Burnaby, British Columbia, Canada. Noted food engineer Torunn Atteraas Garin also developed a process to remove caffeine from coffee.
   Section::::Decaffeination processes for coffee.:Supercritical CO process.
  
  In this process, green coffee beans are steamed and then added to a high pressure vessel. A mixture of water and liquid CO is circulated through the vessel at 300 atm and 65 ºC (150°F). Caffeine dissolves into the CO; compounds contributing to the flavour of the brewed coffee are largely insoluble in CO and remain in the bean. In a separate vessel, caffeine is scrubbed from the CO with additional water. The CO is then recirculated to the pressure vessel.
  
  Section::::Decaffeination processes for coffee.:Swiss Water process.
   Coffee percolators and automatic coffeemakers brew coffee using gravity. In an automatic coffeemaker, hot water drips onto coffee grounds that are held in a paper, plastic, or perforated metal coffee filter, allowing the water to seep through the ground coffee while extracting its oils and essences. The liquid drips through the coffee and the filter into a carafe or pot, and the spent grounds are retained in the filter.
   Another variation of Roselius' method is the indirect organic solvent method. This is very similar to the process described above, only instead of treating the beans directly, water resulting from the soaking of beans is treated with solvents and the process goes on until equilibrium is reached without caffeine in the beans. This method was first mentioned in 1941, and people have made great efforts to make the process more "natural" and a true water-based process by finding ways to process the caffeine out of the water in ways that circumvents the use of organic solvents.
  