How is Coffee Decaffeinated?

What Exactly Is Caffeine?

Caffeine is a chemical compound that is made naturally by a lot of plants. It is classified as a drug because it a stimulant that affects the nervous system. It provides a short term energy boost and alertness in addition to uplifting mood. It is also known to bring on nervousness, insomnia and irritability.

An eight ounce serving of coffee (240ml) typically contains 95 milligrams of caffeine. Individuals who are sensitive to caffeine find even ten milligrams to be troublesome. This is why many people prefer to consume decaffeinated coffee. Close to one billion pounds of decaffeinated coffee is consumed annually, which makes up roughly twelve per-cent of the total global consumption of the brew.

Decaffeinated Vs. Caffeine-Free:

It is important to note that decaffeinated does not mean that the cup of coffee is totally free of caffeine. By U.S. law, as long as 97% of the caffeine is removed from the beans, the coffee made from them can be termed decaffeinated. A cup of decaf will have two to five milligrams of caffeine, sometimes it may even go as high as 20mg. The problem is that not all coffee beans contain the same amount of caffeine. Typically the Robusta beans house around twice the caffeine content as the Arabica beans. Hence, even after being decaffeinated, the coffee grounds made from combinations of Robusta beans will have greater amount of caffeine than coffee ground made from Arabica beans. This is why there is such a huge variation in the amount of caffeine in a cup of regular or decaffeinated coffee.

Studies tracking the amount of caffeine from the same coffee bar or restaurant have found a great deal of variation in the amount of caffeine found in the same cup of coffee measured at different times of the day. It is very difficult to know exactly how much one is consuming. It is noteworthy that decaffeinated espresso based drinks like lattes, which are made from two shots of espresso, can deliver just as much caffeine as one can serving of Coke, roughly thirty-one milligrams.

How Caffeine is Removed from Coffee:

Many people feel that decaffeinated coffee just does not taste good due to the treatments it undergoes, while others feel that due to the chemicals used to remove the caffeine, decaf coffee is not healthy. Still others claim that considering caffeine is a natural product, removing it is unnatural regardless of how it is done. However, a large portion of the coffee drinking population would prefer not to have to deal with its stimulating effects. So is it possible to get a good cup of java with the caffeine removed? Let’s read on to find out.

While there are a number of methods of removing caffeine, they all have a few common characteristics. First caffeine is always taken out from the unroasted green bean regardless of the method used. Since caffeine dissolves in water, all the different processes make use of water to get it out. It needs to be mentioned that regardless of the process used, they all have some effect on the process of roasting and impact how long the coffee stays fresh. In general decaffeinated coffee becomes stale much faster than regular coffee. 

However, removing only the caffeine from the more than one thousand compounds found in this complex bean, is a major hurdle. Many of these substances are also soluble in water, and if water is used as a solvent, it removes many of the sugars and proteins which give coffee its great flavor. If these substances are inadvertently removed with caffeine, it leaves the cup of coffee with a taste of being watered down.  This is why the different processes by which decaffeination is carried out make use of solvents in addition to water to either dissolve caffeine selectively or speed up the process so minimum amounts of other substances are removed.

Ludwig Roselius developed the very first commercially successful method of decaffeinating coffee in 1905. His method required the use of benzene, a hydrocarbon with the potential to be toxic. The current methods make use of safer solvents allowing many producers to claim that their coffee is ‘naturally decaffeinated.’  

The Direct Solvent Method:

The beans are steamed in this method to allow pores to open so solvent can enter with ease. Next the beans are washed directly with a solvent, usually Methylene Chloride or ethyl acetate for about ten hours to extract the caffeine. Eventually the solvent loaded with caffeine is drained and the beans dried.

Methylene chloride’s health is so nominal that the FDA regulations consider it as not posing any health risks at all. This is why they allow up to ten parts per million methylene chloride residue. However, coffee industry’s results are actually closer to one part per million. Ethyl acetate is a naturally occurring substance, found in ripening fruit like blackberries and apples. This is why producers using ethyl acetate as solvent claim that the coffee is decaffeinated naturally. The problem is that the collection of ethyl acetate from fruit is not feasible and it is costly, hence synthetic variants are typically used in its place.

Both of these solvents are very volatile, vaporizing at fairly low temperatures. When coffee is roasted at close to 400 °F, the chances of either of these substances surviving in the bean are next to impossible. This is what makes them safe.

The Indirect Solvent Method:

Resembling the direct solvent method, in way of decaffeinating coffee the beans do not directly touch the solvents. The caffeine is removed by soaking the beans in water which also dissolves many of the oils and flavors from the bean. The water containing the extracts is treated with methylene chloride to remove the caffeine selectively and the water containing the remaining flavors is returned to the beans so they can reabsorb the flavorful compounds back. This is the most commonly used method by large scale commercial decaf producers as it is efficient and cheap.

Swiss Water Method:

The method does not make use of any chemicals. It uses water to remove the caffeine, but not being a selective solvent, the water also extracts other compounds from the bean. This solute is pushed through a carbon filter which captures the larger caffeine molecules while allowing the smaller molecules of oils and other flavorful compounds to pass through.

The flavorless beans are discarded, while the flavor rich water is used again to remove caffeine from a fresh batch of coffee beans. Since the water is already rich with flavorful nutrients and oils, no more flavorful compounds will dissolve in this water. Since it contains no caffeine, the caffeine will dissolve in this water from the fresh batch of beans. This new batch of beans will lose its caffeine but not the flavorful compounds, resulting in decaffeinated coffee that is full of flavor without any hint of chemicals!

Carbon Dioxide Method:

This newest of methods makes use of CO2 instead of chemical solvents. The water laden coffee beans are put in a sealed extraction vessel, while liquid CO2 is forced through the beans under pressure of 1000 pounds per square inch. The carbon dioxide extracts the caffeine selectively, leaving everything else intact inside the bean. The liquid carbon dioxide full of caffeine is transferred into another container where the pressure is released allowing the CO2 to return to its original gas state. The caffeine is left behind in the container. The CO2 gas without the caffeine is ready to be used again in pressurized container with a fresh batch of coffee greens.

Being able to find a really good quality decaf is not easy. This is due to two basic facts. First, the process of decaffeination does to some degree strip the beans of some components that add to the character of the coffee. Second, decaffeinated coffee beans are very hard to roast. The process of decaffeination leaves the beans nearly brown in colour instead of green. Roasters find it hard to control them as they respond inconsistently to heat during roasting. They also contain less moisture content compared to the green bean that hasn’t been decaffeinated, as a result they roast faster.

Rest assured, despite all the treating, it is possible to find a good cup of decaf coffee. Just remember that more than the decaffeination method; the type of roast you purchase is going to have greater impact on flavor. It is best to avoid extra dark, oily roasts. You don’t want to add the havocs of a dark roast to the severity of decaffeination.

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