(BeWellBuzz) A major challenge merchants face when decaffeinating coffee is maintaining flavor. The caffeine contains much of the bean’s yum-factor, and the processing draws out more than caffeine but also other important flavor chemicals. It turns out that the popular stimulant doesn’t separate easily from its vessel, so manufacturers have had to devise methods powerful enough to remove the one constituent without stripping all of the seed’s treasures.
How to Make a Decaf Brew
In the beginning of the last century a German coffee merchant named Ludwig Roselius invented “the Roselius process” of decaffeination. The process involved benzene, a solvent that’s no longer used commercially because of potential toxicity, but elements of his methodology are still used. Today there are three primary methods:
- Swiss Water Process
- Methylene Chloride or Ethyl Acetate Solvents
The Swiss Water Process
Fresh, green coffee beans are soaked in water. The water draws out natural chemicals from the bean, including caffeine but also oils and nutrients. This leaves the beans less nutritious and delicious. To restore flavor and health benefits, the original beans are tossed but we keep the new green coffee extract (GCE), containing all the goodies. The GCE is then passed through charcoal filters, which absorb the caffeine, and is re-used to soak the next fresh batch of beans. This batch soaks in the new and improved water, which replenishes everything but the caffeine as it pulls chemicals from the green bean. The new GCE is again filtered of it caffeine content, and the enriched bean-bath is repeated. After 8-10 hours of this, 99.9% of the caffeine is removed while most of the coffee’s original flavor should be restored. This process is considered higher end because it’s the purest and most expensive. Starbucks employs the Swiss Water Process for its Decaf Organic Serena Blend.
Methylene Chloride or Ethyl Acetate
There are two methods using these solvents, called direct or indirect. The direct method is perhaps the most commonly used by major coffee makers. The green coffee beans are first steamed for 30 minutes and then washed with one of the two chemical solvents, methylene chloride (also dichloromethane) or ethyl acetate. The process is repeated for 10 hours until desired decaffeination is reached, and then the solvent is completely drained. For the next 10 hours the beans are roasted at or above 400°F. The high temperature is sufficient to remove any detectable traces of the solvent, whose boiling point is 114°F.
The indirect method first soaks the beans in hot water for several hours, instead of steaming for 30 minutes. In this case, the first round of beans is often thrown out like in the Swiss Water method. The chemical solvent is then added to the water in order to bind up caffeine. Through an evaporation process, the caffeine is removed from the water and a fresh batch of beans gets soaked in the mostly caffeine-free coffee extract. Also as in the Swiss method, bathing the beans in its own juices helps to maintain and restore flavor while extracting the caffeine. The process is repeated until the manufacturer deems the beans sufficiently decaffed.
NOTE: Methylene Chloride is made in a lab. Ethyl acetate can be extracted from fruits such as apples and bananas, and as such is sometimes used for all-natural caffeine processing; however, most of the time and unless otherwise specified, the solvent is made synthetically.
This method is also known as “supercritical fluid extraction,” and in this case, uses “supercritical carbon dioxide.” When carbon dioxide reaches its critical temperature and pressure, it can act both as a gas and a liquid. So, the carbon dioxide will have a liquid density, but “fill its container like a gas.”
Cool little science lesson.
When used for decaffeination, coffee beans are initially steamed, then soaked for 10 hours in the supercritical CO2.The CO2 nicely targets caffeine without absorbing too much of the other flavor constituents. CO2 is then evaporated and the stimulant goes up with it. Finally, carbon filters are used to clarify the CO2 of caffeine so that it can be reused for the next batch. Starbucks’ Decaf Sumatra utilizes this method.
Decaf, Not Caffeine-Free
Even employing the best methods of our day, coffee is almost impossible to completely decaffeinate. Technically, the tag “decaf” should be 97-99% free of the stimulant; however, this is hardly enforced as it’s both difficult to accomplish and to detect on a cup-for-cup basis. Soda pop that says it’s caffeine free really means they excluded the caffeine additive, which isn’t naturally found in the drink’s ingredients.
Decaf coffee, however, isn’t the equivalent of caffeine-free. Some brews may contain 5-10% or much as 20% of the original content. So if a typical 8oz cup of regular coffee contains roughly 85mg of caffeine (which it does), then the most you’ll get out of a decaf of the same size is 17mg, and you’re more likely to hit a range of 4-12mg. Comparatively, 8oz of black tea offers about 47mg.
In all, if you need a diet completely free of the stimulant, decaf coffee may not be a good choice. But it does significantly cut it out by as little as 80% or as much as 99%. And despite the negative results of extreme overconsumption, many experts today say that for healthy adults, a moderate amount each day is…healthy. Consuming java regularly is shown to be disease preventative, assisting in weight loss and decreasing likelihood of cancer, diabetes, heart disease, even Parkinson’s and Alzheimer’s Disease, and the caffeine is believed at least in part to contribute to the health benefits of coffee.
 Wikipedia. “Supercritical carbon dioxide.” http://en.wikipedia.org/wiki/Supercritical_carbon_dioxide