How is decaffeinated coffee made? Understanding the science behind it

Morning coffee is appreciated by many people and helps start the day. However, it can also have some harmful effects, such as anxiety and nervousness, tremors, increased heart rate, stomach irritation, and headaches. For these reasons, some people prefer decaffeinated coffee.

Today, there are some processes that remove most of the caffeine from the drink, but none of them can achieve 100% efficiency. The process of decaffeinating coffee also removes other chemical components from the beans that contribute to the drink’s aroma and flavor.

Decaffeinated Coffee: How It’s Made

There are a few ways to remove caffeine from coffee. Chemistry professor Michael Crowder explains each one in an article from ConversationSee below how some of the methods work.

carbon dioxide method

To remove caffeine from coffee, producers pump carbon dioxide into a closed environment containing moist coffee beans. The caffeine molecules dissolve and mix with the carbon dioxide.

After the caffeinated carbon dioxide is separated from the beans, the mixture is passed through a container of water or a porous activated charcoal bed capable of filtering out the caffeine. During filtering, other coffee compounds are likely to be left behind. The decaffeinated coffee beans are dried under heat until the remaining carbon dioxide evaporates.

With CO2, between 96% and 98% of the caffeine is removed. The resulting decaffeinated coffee has minimal CO2 residue. On the other hand, this method system uses expensive equipment.

Swiss Water Process

In this method, producers leave green coffee beans to soak in hot water. This extracts caffeine and other chemicals from the beans and passes them into the water.

Next, the beans are placed in another container, this time with fresh, decaffeinated water. The procedure should be repeated ten times, until the coffee beans are almost 100% decaffeinated.

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The water containing caffeine and other substances passes through an activated carbon filter, which retains the caffeine and other chemicals of similar size. However, most of the other compounds remain in the water, which will be used to absorb a new batch of beans. In this way, the flavors lost through steeping can be returned to the decaffeinated coffee.

The Swiss Water Process came into commercial use in the early 1980s. The process is valued for its chemical-free nature and ability to preserve the natural flavor of the coffee. It removes 94% to 96% of caffeine.

Solvent based methods.

This is the most common approach to producing decaffeinated coffee, and has been used since the early 20th century. The method relies on organic solvents, such as ethyl acetate and methylene chloride, which dissolve organic compounds such as caffeine.

Producers can soak the wet beans directly in the solvent or in a mixture of the solvent diluted in water. After the solvent has removed most of the caffeine, the beans are removed from the sauce and dried.

Another way to use this method is to leave the beans in hot water for a few hours. After the coffee is removed from the sauce, producers treat the water with a solvent to remove the caffeine. As with the Swiss water method, producers can reuse the decaffeinated water to return some of the lost compounds to the decaffeinated coffee.

This method removes between 96% and 97% of the caffeine. The most commonly used compound is methylene chloride, which dissolves caffeine better than water. This substance can be toxic depending on the amount.

Above 10 mg per kg of body weight, methylene chloride poses risks. But the remaining amount in decaffeinated roasted coffee is small, about 2 to 3 mg per kg. When the beans are cooked and then roasted at high temperatures, methylene chloride also evaporates.