How Do They Make Decaffeinated Coffee? Introduction to a Fascinating Process.

Wondering how do they make decaffeinated coffee?

One of the primary reasons people drink coffee is to wake up. Whether in the morning or during an exhausting workday.

When you drink decaffeinated coffee, however, you will have a totally different experience. Without caffeine, the effect on your brain is considerably milder.

When we consume caffeine, caffeine molecules compete with a molecule called adenosine for binding to specific receptors in the brain. 

Typically, when these receptors detect a high adenosine level, they transmit a command that slows down brain activity. Which causes fatigue and drowsiness. 

There is a structural similarity between caffeine and adenosine. That allows caffeine to “replace” the adenosine on the brain receptors and prevent the feeling of fatigue.

Despite the increased vigilance that accompanies drinking coffee, and perhaps because of it, many people choose to drink decaffeinated coffee.

About ten percent of global coffee consumption is of decaffeinated coffee. 

But is “free” coffee decaffeinated? How is caffeine separated from coffee and does this process involve health hazards?

How to remove caffeine from the Coffee Beans?

Coffee beans contain over 400 different molecules that give coffee its characteristic taste and smell. 

The challenge of removing caffeine from the coffee beans is to leave as many flavors and odor molecules in them. 

As early as 1906, Ludwig Roselius patented a method of extracting caffeine from coffee. 

In the Roselius’ method, they soak the coffee beans in salt water or acid, the beans evaporated to open their pores and then washed with benzene chemical solvent. 

Roselius used benzene mainly to remove caffeine effectively from coffee without harming other flavors and aromas. 

They don’t use Roselius’ method today, mostly because benzene is a carcinogen even in tiny amounts.

green coffee beans ready to be decaffeinated
Fresh batch of coffee beans ready for decaffeination

What’s left from Roselius Method?

The most common method of removing caffeine from coffee is like Roselius’s method and differs mainly from the solvent used. 

After steaming the coffee beans, they rinse them with methylene chloride or ethyl acetate (a substance found naturally in apples, bananas, and coffee), which binds caffeine well. 

They rinse the coffee beans with water and remove the solvent residue by evaporating the coffee at high temperatures. 

Methylene chloride (Dichloromethane) evaporates at about 40 degrees Celsius, and ethyl acetate evaporates at 77 degrees Celsius. 

They repeat the process several times until they remove about 96 percent of the caffeine from the coffee. 

The U.S. Food and Drug Administration, defines methylene chloride as a hazardous substance if exposed to 10 parts per million (ppm) of it in food. 

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After rinsing and evaporation, decaffeinated coffee usually remains less than one-millionth of a million methylene chloride, which is not Dangerous at all.

After removing the caffeine, the coffee beans will also undergo roasting at a temperature of over 150 degrees Celsius. In that case, the fear of chemical solvent residues in decaffeinated coffee is even smaller.

Is it liquid? Is it gas? No. It’s a supercritical fluid—a combination of liquid and gas.

In 1967, the German chemist Kurt Zusel noticed he could separate the caffeine from coffee with carbon dioxide. 

Supercritical fluid can reach a state of aggregation at high temperatures under pressure. 

Carbon dioxide in the supercritical state is as dense as a liquid. But can pass through tiny openings like a gas.

Based on these properties, Zosel has developed a unique method. He soaked the coffee beans in a pressure vessel with boiling water and steam to open their pores. 

They then pass carbon dioxide through the coffee beans in a supercritical state of aggregation. While absorbing caffeine selectively thanks to its quasi-gaseous property to penetrate through tiny pores.

The caffeine-bound carbon dioxide goes out into a separate tank, where it cools off to a temperature of 25 degrees Celsius and becomes liquid. 

They pass the liquid carbon dioxide through a unique strainer that binds only the caffeine. 

The carbon dioxide goes back to using the supercritical state, and for another round of caffeine removal from the coffee beans. 

This method can remove 96-98 percent of the caffeine in the coffee. 

It harms the taste and smell of the coffee to a lesser extent than the chemical solvent method.

They remove the caffeine from the carbon dioxide and use it for other purposes (like caffeinating soda pop). Then they recycle the carbon dioxide and use it again. 

One advantage that the carbon dioxide process has over the Swiss water process is that the flavor molecules stay in the beans the entire time, which, in theory, lessens the chance that they lose any flavor molecules. 

However, this method’s equipment is quite expensive, so it’s not used very much outside of giant commercial operations.

The Swiss Water Process

For specialty coffee, they use Swiss water processes most often. 

They developed the Swiss water process for decaffeinating coffee using no chemicals—not even carbon dioxide. 

Instead, this method removes the caffeine through solubility and osmosis. 

Like in the carbon dioxide process, they place the green coffee beans in a hot water tank. 

They stay there for several hours and essentially start brewing flavors, oils, and caffeine leach into the water. 

The coffee water then passes through a carbon filter that captures only the caffeine molecules. 

The result is a pile of flavorless caffeine-free beans, a tank of flavored green coffee extract, or GCE. 

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They compose the GCE of the same oils and other flavor molecules as regular green beans—just without the caffeine. 

Here’s where osmosis comes in. They throw away the flavorless beans, bring New beans (full of flavor), and dump them into the GCE. 

Through osmosis, they draw the caffeine out of the new beans and into the water. Because the beans and the water are in balance concerning their flavor molecules, they lose only the caffeine. 

It means that the beans lose the caffeine, but keep much of their flavor. 

Look for bags of decaffeinated coffee that say “Swiss water process,” and you’ll know that they processed the coffee without potentially harmful chemical solvents. 

You may also notice that decaffeinated beans may cost more than their caffeinated counterparts because of the extra processing involved.

While this method does not use chemicals, it is less binding to caffeine, removing only 94-96 percent of the initial amount of caffeine in beans.

Growing decaffeinated coffee

Unlike all the methods we have described so far, Japanese researchers have reported that they have produced a unique strain of coffee beans with the help of genetic engineering. The caffeine content is initially 70 percent lower than the caffeine content in non-genetically engineered coffee beans. 

This development does not come close to commercial processes’ efficiency, but it is an exciting idea that may become a commercial one day. 

Other researchers have found in Ethiopia a rare strain of Arabica coffee beans whose caffeine content is naturally low. It may be possible in the future to hybridize it with the commercial varieties of Arabica, the most common type of coffee.

Health Consequences From drinking Decaffeinated

Once we understand how to get the caffeine out of coffee, we will realize how decaffeinated coffee affects our health. 

First, it is essential to clarify that despite its name, decaffeinated coffee is not entirely caffeine-free. 

To illustrate, while a regular cup of coffee contains between 70 and 150 mg of caffeine (the exact amount depends on the type of beans, the method of roasting, etc.), a cup of “decaffeinated” coffee still contains about 5 mg of caffeine (also here, the amount The same variable). 

If so, the effects of decaffeinated coffee on health may not be so different from the results of drinking regular coffee, which is probably not noticeable. 

For example, a comprehensive study that pooled results from 36 studies, all of which together encompassed more than a million participants, found no direct link between decaffeinated coffee consumption and risk.

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