Decaffeination

The decaffeination is a process by which coffee beans or tea leaves contained caffeine is by physical solvents partially or almost completely withdrawn. Residues of the solvent escape at the latest when the coffee beans are roasted. Only physiologically harmless solvents that largely evaporate without heating can be used for tea.

Coffee decaffeination

In the case of coffee, the decaffeination process begins with the beans that are still green and unroasted. In general, the beans are first allowed to swell with warm water or steam . The caffeine contained in the beans is then extracted with a solvent . Since only part of the caffeine contained can be extracted in one process cycle, the process has to be repeated very often in order to reach the maximum 0.1 percent residual content that is prescribed in the EU for decaffeinated coffee. Coffee contains around 400 chemical components that are largely responsible for the taste and aroma of the brewed beverage. Depending on the decaffeination process, these components are also removed to a greater or lesser extent, which can lead to undesirable changes in the taste of the coffee.

Researchers around the world are working on the production of coffees with reduced caffeine content. In 2004, a Brazilian research group found several variants that contained practically no caffeine in genetic tests with Arabica coffee. Working groups at the Universities of Glasgow , Tokyo and the Integrated Coffee Technologies Institute in Hawaii are researching the production of decaffeinated coffee plants using genetic engineering . In the future it could be possible to do without the costly decaffeination completely.

Roselius method

The first commercially used process for decaffeination was developed and patented by Ludwig Roselius in 1903/1905 . Roselius suspected that his late father, who was a heavy coffee drinker, had poisoned himself with caffeine. So he was looking for a way to remove the caffeine from coffee. In the Roselius process, the beans are pre-swollen with salt water. The toxic and carcinogenic benzene is used as a solvent in the extraction , which is why this process is no longer used today. In this way, decaffeinated coffee was in most areas of Europe as Kaffee Hag , in France as Café Sanka and later sold in the US under the brand name Sanka. Today, because of the harmful benzene, other decaffeination processes are used for Kaffee-HAG and Sanka.

Swiss Water Process (SWP)

In this process, which was developed by the Swiss Water Decaffeinated Coffee Company in the late 1970s, the first step is to treat beans with hot water until all of the caffeine and other solid components have been dissolved out. The beans from this first step are disposed of. The water with the dissolved caffeine and other coffee components then runs through an activated carbon filter , with which the caffeine molecules are removed. New coffee beans are added to the now decaffeinated water in a similar filter device. Since the water is already enriched with dissolved coffee components, this time only the caffeine is dissolved and the other taste-determining ingredients of the coffee beans are retained. The process is repeated until the desired level of decaffeination is achieved. The beans are then dried and are supposed to retain most of their taste and aroma, which is, however, controversial among experts. A disadvantage of the process is the relatively high costs, since the caffeine bound with the activated carbon cannot be recovered and sold separately. Today there are only a few plants in the world that work with the Swiss water process.

Direct procedure

After about 30 minutes of exposure to steam, the beans are stored for 10 hours in dichloromethane or ethyl acetate as the extraction agent (solvent). The extractant is then poured off and residues are removed in a further 10-hour drying step. The complete removal of the solvent is particularly important with dichloromethane, as this is suspected of being carcinogenic. Coffee that has been decaffeinated with ethyl acetate is sometimes also referred to as naturally decaffeinated coffee, since ethyl acetate is also found in various fruits and vegetables. Decaffeinating with this method is comparatively inexpensive.

Indirect method

In the indirect process, all water-soluble components are first removed from the beans with hot water, just as when the coffee is later boiled. Caffeine is then extracted from this solution with the aid of dichloromethane or ethyl acetate. The decaffeinated coffee solution is then heated with new beans, whereby a solubility equilibrium is established and only the caffeine is extracted from the beans. This process essentially corresponds to the Swiss water process, but using a different solvent.

Carbon dioxide process

In this process, coffee beans pretreated with steam are rinsed with supercritical CO ₂ at a pressure of 73 to 300 bar, thus dissolving the caffeine in the fluid phase. The carbon dioxide is allowed to evaporate, leaving the pure caffeine behind. The CO ₂ is then recompressed, condensed and reused.

Triglyceride Process

The unroasted beans are treated in a hot water-coffee solution to bring the caffeine to the surface of the beans. In a separate container, the beans are then immersed in hot coffee bean oils for several hours . The triglycerides contained in the oils remove the caffeine from the beans, but not the flavor and aroma substances. The beans are then separated from the oil and dried.

Caffeine content of decaffeinated coffee

Virtually all decaffeinated coffees still contain residual caffeine. In the EU, coffee with a caffeine content of less than 0.1 percent can be described as decaffeinated coffee . In other countries there are less restrictive rules, so the caffeine content can be higher there. According to results from the Florida Maples Center for Forensic Medicine , ten cups of decaffeinated coffee can contain roughly the same amount as one to two cups of regular coffee. The measured caffeine content was 3 to 15.8 mg per cup for decaffeinated espresso and 6 to 6.7 mg per cup for decaffeinated coffee. In comparison, undecaffeinated coffee contains around 85 mg of caffeine per cup.

Decaffeination of tea

Tea is usually decaffeinated using the carbon dioxide process already used for coffee. Different types of tea can vary in their caffeine content, and young leaves and buds also have a higher weight-related caffeine content than old leaves and stems. A cup of tea contains around 40 to 50 mg, roughly half the caffeine in a cup of coffee.

It is possible to influence the content of tea through a special brewing procedure. If you brew the same tea several times, the caffeine content is significantly reduced. For example, in experiments with the second five-minute brewing, tea only contained a third of the first infusion of caffeine, which corresponds to 23 percent of the total caffeine contained in the leaves.

Web links

• Process for the production of coffee and coffee substitutes (section 2.2 Decaffeinated and low-irritant coffee)
• Ryan Jacobs: Caffeine and The Bean. In: ineedcoffee.com
• People who are sensitive to the effects of caffeine can tolerate decaffeinated products

Individual evidence

1. ^ Colin Blackstock: Scientists discover decaf coffee bean. In: Guardian Unlimited , June 24, 2004.
2. ↑ Marietta Gross: Discovered naturally decaffeinated coffee. In: innovations report , June 24, 2004.
3. ↑ Coffee without caffeine, cigarettes without nicotine. ( Memento of the original from October 9, 2007 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. In: transgen.de , June 4, 2007.  
4. ↑ Donald Schoenholt: Decaffeinated - not decapitated ( Memento of the original from May 8, 2009 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. Tea & Coffee Trade Journal, February 1, 1993.  
5. ↑ SWISS WATER® Process 101 ( Memento of the original from October 27, 2007 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. Swiss Water Decaffeinated Coffee Company.  
6. ↑ Swiss Water Process. In: ronainc.com
7. ↑ Naturally Decaffeinated / Decaf Organic Swiss Water Process Coffee ( Memento of the original from June 7, 2007 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. Bib River Coffee Company.  
8. ↑ Decaffeinated Coffee: Swiss Water Process. In: coffeereview.com .
9. ↑ History of the SWISS WATER® Decaffeination Process. ( Memento of the original from December 30, 2006 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. In: swisswater.com , January 4, 2007.  
10. ↑ "Study: Decaf coffee is not caffeine-free". In: ScienceDaily.com , UPI, October 10, 2006.
11. ^ Tea and Caffeine. In: Upton Tea Imports Newsletter , Vol 16, Issue 1, 2003.
12. ^ Hicks, Hsieh, Bell: Tea preparation and its influence on methylxanthine concentration. In: Food Research International , Volume 29, Edition 3-4, 1996, doi : 10.1016 / 0963-9969 (96) 00038-5 .