Caffeine & Decaffeination

Caffeine is found in varying quantities in the leaves, and fruit of some plants, where it acts as a natural pesticide that paralyzes and kills insects feeding on the plants. It is most commonly consumed by humans in infusions extracted from the cherries of the coffee plant and the leaves of the tea bush, as well as from various foods and drinks containing products derived from the kola nut.

Caffeine is a bitter, white crystalline xanthine alkaloid, a psychoactive stimulant drug that was discovered by a German chemist, Friedrich Ferdinand Runge, in 1819. He coined the term “kaffein”,which in English became caffeine.

Caffeine is the world’s most widely consumed psychoactive substance, but unlike many other psychoactive substances it is legal and unregulated in nearly all jurisdictions.

In humans, it is a central nervous system (CNS) stimulant, having the effect of temporarily warding off drowsiness and restoring alertness.

In 1903 Ludwig Roselius, a German coffee importer and his assistant Karl Wimmer discovered a process to remove caffeine from the beans without destroying the flavour.

Discovering the decaffeination process actually came about as the result of an accident. Coffee beans from Nicaragua had become water soaked during shipment. When the “ruined” beans arrived at Roselius’ coffee warehouse, his researchers determined that the exposure to water had extracted much of the caffeine without affecting the taste except for some saltiness. Soon they figured it out.

The decaf process that Roselius and Wimmer invented used steam and chemical solvents. A later Swiss process would only use water.

Decaffeinating Coffee

A typical 12oz cup of caffeinated coffee contains between 120 -180mg of caffeine while a decaffeinated cup of coffee the same size has between 2 – 6mg.

In most decaffeination methods, chemical solvents such as methylene chloride or ethyl acetate are used to strip caffeine molecules from the green coffee bean.

There are two types of caffeine removal processes: Direct and Indirect.

The Direct Process

In the direct process uses solvents in the first two stages of decaffeination as the caffeine-absorbing agent. In effect, the solvent comes in direct contact with the coffee bean.

The most widely used solvents are chemicals: methylene chloride or ethyl acetate. In the direct method the coffee beans are first steamed for 30 minutes and then repeatedly rinsed with either methylene chloride (Dichloromethane/DCM) or ethyl acetate for about 10 hours. The beans are then steamed for an additional 10 hours to remove any residual solvent.

The Indirect Process

In the indirect method beans are first soaked in hot water for several hours, essentially making a strong pot of coffee. Then the beans are removed and either methylene chloride or ethyl acetate is used to extract the caffeine from the water. As in other methods, the caffeine can then be separated from the solvent by simple evaporation. The same water is recycled through this two-step process with new batches of beans. Equilibrium is reached after several cycles, where 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 flavourings are lost. Because water is used in the initial phase of this process, sometimes indirect method decaffeination is referred to as “water processed” even though chemicals are used.

Organic coffee cannot be processed using chemical, so organic coffee is usually decaffeinated using SWISS WATER Process.

The Swiss Water Process is a method of decaffeinating coffee beans developed by the Swiss Water Decaffeinated Coffee Company. To decaffeinate the coffee bean by the Swiss Water method, a batch of green (un-roasted) beans is soaked in hot water, releasing caffeine.

When all the caffeine and coffee solids are released into the water, the beans are discarded. The water then passes through a carbon filter that traps caffeine but lets the coffee solids pass through. The resulting solution, called “flavour charged” water by the company, is then put in a similar filtration device, and new coffee beans are added.

The process repeats, filtering out all the caffeine until the beans are 99.9% caffeine free. These beans are removed and dried, and thus retain most if not all of their flavour and smell.
Since the flavour charged water cannot remove any of the coffee solids from the new beans, only the caffeine is released.
Although the process originated in Switzerland in the 1930s, today the world’s only Swiss Water decaffeination facility is based near Vancouver, British Columbia, Canada.

Decaffeination Standards

In the US, decaffeinated coffee has a guideline that requires 97% of the caffeine to be removed from a green coffee bean. Being a guideline, as opposed to a standard, provides roasters more flexibility in terms of the percent of caffeine removed.

However, in Canada and the international community, 99.9% caffeine-free is the recognized standard for decaffeinated coffee based on the maximum allowable caffeine level remaining in a decaffeinated green coffee bean.