Decaffeination Explained
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A coffee must have at least 97% of its caffeine removed to qualify as decaffeinated in the United States.
Each five-ounce cup of decaffeinated coffee contains less than 5 milligrams of caffeine.
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Decaffeinated coffees tend to cost more than their non-caffeinated counterparts. This is because of the
additional labor, equipment and expenses required for caffeine removal. Coffee beans are decaffeinated
before they are roasted, when the process can be done more cost effectively and with the least effect on the
beans’ flavor.
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Decaffeinated coffee was introduced to the United States just before World War I.
How the Caffeine is Extracted
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Decaffeinating usually involves the use of a solution containing water and coffee flavor elements,
plus a decaffeinating agent. Although caffeine is water soluble above 175° F, the use of water alone is
rarely used to decaffeinate coffee because it strips away too many essential flavor and aroma elements.
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There are two basic methods of decaffeination: direct and indirect contact.
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In the direct method, the beans come directly in contact with the decaffeinating agents (most commonly methylene chloride)
after being softened by steam.
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In the indirect contact method, a water/coffee solution is used to draw off the caffeine. After being separated from the beans,
the solution with the caffeine is then treated with a decaffeinating agent.
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In both methods, the decaffeinating agent is removed from the final product.
A Look at Different Decaffeinating Methods
Methylene Chloride Direct Contact Extraction also known as The European Prep Method
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The green (unroasted) beans are placed in a rotating drum and softened by steam for about 30 minutes.
Afterward the beans are repeatedly rinsed for about 10 hours with methylene chloride which removes the caffeine from the beans.
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After the thorough rinsing, the caffeine-laden solvent is drained away and the beans are steamed a second time so the remaining
solvent can evaporate. This steaming lasts between 8 and 12 hours.
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In the final step, the beans are either air or vacuum dried to remove any excess moisture from the decaffeinated beans.
Methylene Chloride Indirect Contact Extraction also known as “Water Process”
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The green beans soak for several hours in a waterbath at almost boiling temperatures. Gradually the caffeine
as well as other water-soluble compounds dissolves into the solution to saturation.
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The water-based coffee solution is drained away and treated with methylene chloride which bonds with the caffeine.
The resulting mixture is then heated to evaporate the solvent and caffeine.
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Finally, the mixture is reunited with the beans allowing them to reabsorb most of the coffee oils and flavor elements.
The solvent never touches the beans.
Swiss Water Process Indirect Contact Extraction
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Unroasted beans are circulated and soaked in hot water to saturate it with water soluble organic coffee compounds
including caffeine, also known as “flavor-charged water.” The beans are then discarded.
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Activated carbon filters then remove the caffeine from the “flavor-charged water” that is used to decaffeinate
the next batch of beans.
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The new batch of beans is then soaked in the hot flavor-charged water. Since the water is already saturated with coffee
compounds, but deficient in caffeine, the new batch of beans loose the caffeine, but retain other (flavor impacting)
water soluble compounds.
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The beans are then dried and bagged for sale and the solution is decaffeinated with activated carbon filters and reused
to decaffeinate the next batch of beans
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The coffee industry often refers to this as the Swiss Water Process because a Swiss company originally developed
and patented the procedure.
Consumer Awareness
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Depending on which method is used, the loss of coffee flavor and aroma in the brewed beverage will vary.
Any minimal solvent that may exist in the beans following decaffeination is removed during the roasting process
and considered safe and will not detract from the enjoyment of true specialty coffee.
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Every method of decaffeination uses water. Therefore, coffees that carry a “Water Processed” label are not
necessarily decaffeinated by the “Swiss Water Process”.
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Also, coffee may be described as “naturally decaffeinated.” This phrase is a marketing term that suggests the coffee
has been decaffeinated without the use of any chemicals. There is no specific “natural process”.
Notable
* U.S. Food and Drug Administration, the U.S. Surgeon General, National Academy of Science, American Medical Association, American Academy of Family Physicians, National Cancer Institute, The Centers for Disease Control, American Cancer Society, National Research Council on Diet and Health, International Food Information Council, the Framingham Heart Study, the Association of Women's Health, Obstetric and Neonatal Nurses.
Different coffees contain varying levels of caffeine, mainly depending upon their botanical variety. An arabica coffee
has approximately half the caffeine content of a robusta coffee. Depending upon the type of bean, brewing method, and the
amount of coffee used, a five ounce cup of coffee will contain from 70 - 155 milligrams of caffeine. Based on its review of
medical studies, the Institute of Food Technologists notes that moderate amounts of coffee, less than 600 milligrams a day,
are not considered harmful to the average healthy adult. It would take some time to find all of the studies, but we could say:
In fact, studies* have indicated that there are many health benefits of caffeine taken in moderate amounts throughout the day.
U.S. Food and Drug Administration, the U.S. Surgeon General, National Academy of Science, American Medical Association,
American Academy of Family Physicians, National Cancer Institute, The Centers for Disease Control, American Cancer Society,
National Research Council on Diet and Health, International Food Information Council, the Framingham Heart Study, the
Association of Women's Health, Obstetric and Neonatal Nurses.