How is decaf made?

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Decaffeination is the process of removing caffeine from coffee beans. There are several methods used to decaffeinate coffee, all of which are done while the beans are still green. The most common methods include the use of chemical solvents, water processing, and the supercritical carbon dioxide method.
  1. Chemical Solvent-Based Methods: These methods involve the use of chemical solvents such as ethyl acetate or methylene chloride to extract caffeine from the coffee beans. There are two main variations of this method: the direct-solvent process and the indirect-solvent process.
    • Direct-Solvent Process: In this method, coffee beans are steamed for about 30 minutes to prime them for caffeine extraction. Then, they are rinsed with either methylene chloride or ethyl acetate for about 10 hours. The caffeine-laden solvent is then drained away and residual solvent is removed by steaming the beans again1.
    • Indirect-Solvent Process: In this method, coffee beans are soaked in water at a rolling boil for several hours. The water collects the flavor and oil components from the beans, which are then drained and transferred to another tank and washed for about 10 hours with either methylene chloride or ethyl acetate. The chemical solvent selectively bonds with the caffeine molecules and extracts them out of the coffee. The remaining mixture is then heated to evaporate the solvent and caffeine. The beans are then recombined with the water to reabsorb the coffee oils and flavor compounds1.
  2. Non-Solvent Based Methods: These methods do not use chemical solvents to decaffeinate coffee. The most common non-solvent based method is the Swiss Water Process.
    • Swiss Water Process: This method relies on caffeine solubility and osmosis to remove caffeine from coffee beans. First, coffee beans are soaked in hot water to "dissolve" caffeine, however, sugars and other flavor compounds in coffee also dissolve into the water. In order to create flavorful coffee, the resulting mixture is run through a charcoal filter. This process leads to tasting notes from the specific coffee to be retained, being that the process uses water as a solvent for caffeine as opposed to other solvents13.
  3. Supercritical Carbon Dioxide Method: This method uses carbon dioxide (CO2) under high temperatures and pressure to act like both a gas and a liquid. This supercritical CO2 reaches into the crevices of coffee beans like a gas but dissolves caffeine like a liquid. After the beans have been soaked in water (a process that expands cell structures and makes it easier to extract the caffeine molecules), they are exposed to supercritical CO2 for several hours. The caffeinated CO2 liquefies and evaporates, and the beans are then processed. Because this method leaves the carbohydrates and proteins intact, there is less change in taste as a result of decaffeination2.
Each of these methods has its pros and cons, and the choice of method can affect the taste and quality of the decaffeinated coffee. It's also worth noting that while these methods significantly reduce the caffeine content in coffee, decaf coffee is not completely caffeine-free. To be certified as a decaf coffee, no less than 97% of the caffeine content must be removed5.
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