The Caffeine Molecule (contained in coffee)

All decaf (decaffeination) processes happen in the green and unroasted state of coffee and use water. There are many articles on the web explaining how Decaf Coffee is made. We'll just list a quick overview of the 4 main decaf processes

Solvents used in decaffeination

Given numerous health scares connected to early efforts in decaffeination (the hit list of toxic solvents includes: benzene, trichloroethylene (TCE), dichloromethane and even chloroform) the solvents of choice have become methylene chloride and ethyl acetate. Note that these processes have been approved by the FDA and the solvents will evaporate during exposure to high heat such as the roasting and brewing processes.

Indirect–Solvent Based Process

In the indirect-solvent method the coffee beans are soaked in near boiling water for several hours, which extracts the caffeine as well as other flavor elements and oils from the beans.

The water is then separated and transferred to another tank where the beans are washed for about 10 hours with either methylene chloride or ethyl acetate. The molecules of the chemical solvent selectively bond with the molecules of caffeine and the resulting mixture is then heated to evaporate the solvent and caffeine.

Direct–Solvent Based Process

In this method of decaffeination the beans are steamed for about 30 minutes in order to open their pores. Once the coffee beans are receptive to a solvent, they are repeatedly rinsed with either methylene chloride or ethyl acetate for about 10 hours to remove the caffeine. The caffeine-laden solvent is then drained away and the beans are steamed again to remove any residual solvent.

Swiss Water Process SWP

This chemical-free water decaffeination process was 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 finally introduced to the market and its facility is based near Vancouver, British Columbia, Canada.

This particular method of decaffeination is different from what we’ve so far seen in that it does not directly or indirectly add chemicals to extract the caffeine. Rather, it relies entirely on two concepts, namely solubility and osmosis, to decaffeinate coffee beans.

It begins by soaking a batch of beans in very hot water in order to dissolve the caffeine. The water is then drawn off and passed through an activated charcoal filter. The porosity of this filter is sized to only capture larger caffeine molecules, while allowing smaller oil and flavor molecules to pass through it.

Consequently we end up with beans with no caffeine and no flavor in one tank, and caffeine-free “flavor charged” water (aka “Green Coffee Extract”) in another tank.

And here’s where the magic happens. The flavorless caffeine-free beans are discarded, but the flavor rich water is reused to remove the caffeine from a fresh batch of coffee beans.

Since this water already is saturated with flavor ingredients the flavors in this fresh batch can’t dissolve; only caffeine moves from the coffee beans to the water. So the result is decaffeination without a massive loss of flavor.

Coffees decaffeinated by this method are always labeled as “SWISS WATER” Decaf.

This method is almost exclusively used for decaffeination of organic coffee.

Coffee decaffeinated using the environment-friendly Swiss Water Process undergoes regular caffeine level audits to ensure compliance to 99.9% caffeine-free.

Carbon Dioxide CO₂ Process

The Carbon Dioxide (CO ₂) Method is the most recent method. It was developed by Kurt Zosel, a scientist of the Max Plank Institute, and uses liquid CO₂ in place of chemical solvents. It acts selectively on the caffeine, i.e., it releases the alkaloid and nothing else.

In the CO ₂ decaffeination process, water soaked coffee beans are placed in a stainless steel container called the extraction vessel. The extractor is then sealed and liquid CO ₂ is forced into the coffee at pressures of 1,000 pounds per square inch to extract the caffeine.

The CO ₂ acts as the solvent to dissolve and draw the caffeine from the coffee beans, leaving the larger-molecule flavor components behind. The caffeine laden CO ₂ is then transferred to another container called the absorption chamber. Here the pressure is released and the CO₂ returns to its gaseous state, leaving the caffeine behind. The caffeine free CO₂ gas is pumped back into a pressurized container for reuse.

Because of its cost, this process is primarily used to decaffeinate large quantities of commercial-grade, less-exotic coffee found in grocery stores.

Read more at:

http://en.wikipedia.org/wiki/Decaffeination

http://antoine.frostburg.edu/chem/senese/101/matter/faq/decaffeinating-coffee.shtml