Carbon dioxide process of decaffeination

The most selective process for removing just caffeine and not the other flavor precursors from coffee is carbon dioxide.

The coffee beans are sprayed with steam and hot water to raise their water content to 35%. Following the hydration of the coffee beans, they are pneumatically blown to the top of a 280-foot tower. The walls of the chambers in the tower are 6 inches thick and clad on the inside with stainless steel.

After being shot up into the tower the beans then begin to fall down. As the beans are falling supercritical carbon dioxide is pumped up through the beans. Supercritical fluid extraction allows for waste separation and minimization, as well as solvent recycling. Other advantages of supercritical extraction include high efficiency, high extraction rates and more selectivity.

Due to the supercritical nature of the CO2, it behaves more like a liquid than a gas. In this sate it has other liquid-like properties, such as the ability to dissolve other material when it is in a heavy glass or steel container under pressure. Extraction processes that use supercritical CO2 leave no such residue. Also, supercritical CO2 is selective exclusively for the caffeine.

Liquid CO2 is forced at a pressure of 1,000 pounds per square inch into the extraction chamber and when the CO2 comes into contact with the coffee beans, it passes through them and captures the caffeine, leaving the coffee beans with the caffeine in tow, the flavor compounds within the coffee bean intact.

CO2 does not affect the carbohydrates (sugar, starch) and peptides that during roasting are converted into the various compounds responsible for the flavor and aroma of brewed coffee. The caffeine-laden carbon dioxide is then blended into a column of water.

After being blended into water it flows into a chamber where the pressure drops from supercritical pressure to normal atmospheric pressure.

When the pressure comes back to normal atmospheric pressure, the caffeine is attracted to the water as the CO2 evaporates. This carbon dioxide is then captured to be recycled back into the process.
Carbon dioxide process of decaffeination

History of coffee decaffeination

From its earliest history, there were health concerns regarding coffee and its effects. Decaffeinated coffee was first developed commercially in Europe 1900.

Decaffeination with chemical solvents such as methylenchloride or acetyl acetate was first successfully applied by Roselius in ’Kaffee HAG’. Dr. Ludwig Roselius’ original process for decaffeinating coffee was patented in Germany in 1905.

Before the First World War Roselius extended his business to the United States and built a coffee extraction plant at New Brunswick, New Jersey.

In USA the patent issued to Meyer, Roselius and Wimmer in 1908. The process as described in a 1908 patent consists of first, moisturizing green coffee to at least 20% to facilitated transport of caffeine through the cell wall and then contacting the moistened beans with solvents.

Until the 1980s, synthetic organic solvents commonly were used in the United States to extract the caffeine. 

The so called ‘water decaffeination’ process was developed as an alternative by General Foods around 1941 and was patented in 1943.

In the early 1980s, coffee was implicated as a possible cause of birth defects, benign breast lumps, pancreatic cancer and heart disease. Sales of decaffeinated coffee rose dramatically.

Until the mid-90s, decaffeinated coffee was considered to be flavorless, bitter and a poor substitute for regular coffee. As the process of decaffeination has improved, so has its market share with nearly 30 percent of the specialty and gourmet coffees being decaffeinated.
History of coffee decaffeination

Coffee decaffeination process

Caffeine is a physiologically active component in coffee, was been studied intensively.

The process of decaffeinating coffee began at the turn of the last century, in Germany. Decaffeinated coffee means in the EU countries a maximum caffeine concentration of 0.1% related to the dry mass; in the US, it means less than 3% of the amount initially present in the beans.

Today there are only three primary decaffeination methods used by the coffee industry.
*The Swiss water process or water only method 
Swiss water decaffeination almost always uses high quality arabica beans.

This process does not use chemicals. In this process method the green coffee beans are soaked in water for several hours, which removes about 97 percent of the caffeine as well as a few of the flavor components.

*The water decaffeinated method 
The method was first mentioned in 1941 by Berry and Walters. It uses green coffee extract with equilibrium quantities of non-caffeine soluble solids and removal of caffeine from the extract with dichloromethane on liquid-liquid extraction.

In water decaffeination process, sometimes chemicals rather than charcoals filters, are used to extract the caffeine. In this process, no solvent touches the beans. After the beans are steamed, they are soaked in water in big vats, which removes the caffeine along with all the soluble solids in the beans.

*The solvent method 
Certain solvents, such as methylene chloride and common ethyl acetate, are the most widely used chemical compounds to decaffeinate coffee.

A raw green beam is softened with steam and water allowing bean to double in size. The beans are vibrated for about an hour in the solvent, which loosens the caffeine and combines it with the chlorine.

The commercial decaffeination process is at present carried out on the green coffee beans before roasting.
Coffee decaffeination process