Decaffeinated Coffee

Decaffeinated coffee or "decaf" is coffee that has had most of the caffeine removed. By weight, the amount of caffeine found naturally in coffee is only about 1% for the Arabica and 2% for the Robusta coffee beans.

When you read "97% Caffeine Free", 97% of that 1% or 2% has been removed.

There are currently two methods used commercially that remove caffeine from coffee: European Process Swiss Water Process:

Most decaf coffees are made using a chemical process first used in Europe. This process involves soaking the beans in water and then "washing" them in methylene chloride to absorb the caffeine from the bean. After this, the beans are rinsed clean of the chemicals, dried and shipped to the coffee roasters. The advantage of this method is that it provides decaf coffee with more flavor than the Swiss water processing. Although there is virtually no trace of any chemicals left in the bean after roasting, some people are uncomfortable knowing that the coffee they are drinking was chemically processed.

Swiss Water Process

The second method is known as "Swiss water processing". This process uses no chemicals, but rather hot water and steam to remove the caffeine from the coffee. The "life" of the bean is taken into the water, and then the water solution put through activated charcoal filters to remove the caffeine. Once the caffeine is removed, these same beans are then put back into the decaffeinated solution to re-absorb everything except the caffeine. The beans are then dried and shipped to the roasters. The disadvantage is that the water processing removes more than just the caffeine. Some of the oils from the coffee bean are removed as well, making it less flavorful.

The best thing to do for those who really want this kind of decaf is to start out with a high quality, Arabica bean. Even though some of the flavor will be lost, there will still be a lot left to enjoy.

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Drinking decaffeinated coffee is, in theory, a way of enjoying the beverage while eliminating the caffeine and preserving the taste. While improvements have been made to the processes, the taste of caffeinated coffee is not preserved perfectly, rocess completely eliminates all of the caffeine.

Caffeine and Taste

To understand decaffeination processes completely, one must consider the function of the caffeine molecule, with specific attention to taste. The caffeine molecule is a bitter alkaloid, so it contributes to acidity as well as the bitter properties of coffee. Removing this molecule will alter those taste factors. Other flavor compounds are also diminished or removed in the decaffeination process. This means that the taste of decaffeinated coffee is usually inferior to that of caffeinated coffee.

Labeling Practices

It is important to note that the Food and Drug Administration of the United States has no regulatory authority on coffee. Consequently, "decaffeinated" coffee can vary wildly. A product may contain anywhere between 2 and 13 milligrams of caffeine and still be labeled "decaffeinated". Several studies have shown that store bought decaf has a higher ratio of caffeine, so you probably want to purchase your decaffeinated coffee beans from a gourmet roaster. Furthermore, random samplings of brewed coffee suggest that - surprise - human error exists so that sometimes that cup of decaf is actually just regular coffee in an orange-handled pot. If you are extremely concerned about caffeine or sensitive to its effect, you should buy the beans from a reputable source and brew the coffee yourself.

Two Types of Decaf Processes

There are two types of decaffeination processes. The first is called the Swiss Water Process method. Decaf coffee made with this method can be found at most gourmet coffee shops, organic food grocery stores. The other decaffeination processes use some sort of a chemical solvent. In this article, I'll explain the essential aspects of the chemical removal process then I'll discuss a specific variation of the chemical process termed the Super Critical Carbon Dioxide method.

A Common Denominator

In all of the decaffeination processes, the green coffee beans begin the journey by being steamed and/or soaked in water. This makes the caffeine soluble and primed for extraction.

The Swiss Water Process Method

The Swiss Water Process is popular among its advocates because it does not use chemicals. Instead, a green coffee extract is used. This green coffee extract is almost caffeine-free. Due to chemical solubility laws, the caffeine will move from an area of higher concentration (the bean itself) to an area of lower concentration (the extract). Since the extract contains essential oils and the other valuable components of the bean, mostly caffeine seeks its way into the extract and leaves behind the desirable components of the coffee. Done properly, this organic method successfully removes 94 - 96% of the caffeine while it retains more of the flavor compounds present in the essential oils than the chemical methods. Keep in mind that Swiss Water Process coffee beans are generally more expensive than beans treated with a chemical solvent. This is due to the fact that Swiss Water Processing almost always accompanies high-quality arabica beans, while chemical processes are used on both arabica and robusta beans.

The Chemical Solvent Method

The chemical solvent method is the most commonly used method for removing the caffeine from coffee. Chemical methods remove the caffeine better than the Swiss Water Process method because the solvents used can target caffeine most evenly and effectively. Common solvents include methylene chloride, ethyl acetate, and highly pressurized carbon dioxide. After the green beans are moistened they are then immersed in the solvent. After the solvent performs its action, the beans are rinsed with water. After the beans have been rinsed, they are steamed. Residual solvents evaporate in the steam. The rinsing and evaporation systems collect the solvent for recycling and re-use. Any remaining solvent will be burned off in the roasting process. The chemical caffeine method will remove 96 - 98% of caffeine.

The Supercritical Carbon Dioxide Method

The Supercritical Carbon Dioxide method is a chemical method that is somewhat dissimilar to the other chemical methods; therefore it deserves special attention. This method uses carbon dioxide at 250 - 300 times normal atmospheric pressure. Carbon dioxide in this form looks like a liquid in terms of its density, but it has the viscosity of a gas. It is a very effective solvent at the high pressures. When the coffee beans are exposed to the solvent, the caffeine migrates to the solvent. When the removal of caffeine is complete, the now caffeine-rich carbon dioxide is passed through either an activated charcoal bed or a bath of water to absorb the caffeine for re-use. Like other chemical methods, the Supercritical Carbon Dioxide method removes 96 - 98% of the caffeine. Carbon dioxide is inexpensive to obtain and non-toxic.

One might compare a naturally mellow (low acidity) cup of caffeinated coffee with a decaffeinated version of a high acidity coffee. If you prefer a coffee that is known for bitterness or acidity in the caffeinated version, the same coffee in a decaffeinated state will taste "flat" in comparison. At the same time, the other characteristics of that coffee will be brighter since they aren't masked by so much bitterness or acidity. It is kind of like an Elvis Presley song. Often times there are brilliant bass lines that aren't noticed until the vocal track has been removed. In these moments, the full complexity of the song is realized. On the flip side, removing the vocals could reveal an uninteresting tune that is better in a complete state.

Until a method is developed which will completely eliminate caffeine while preserving other flavor constituents of coffee, we will have to tolerate these imperfect methods. The best thing to do is to try several different brands of decaffeinated coffee until you settle on the one or two that taste the best and feel as though they have the least amount of caffeine.