Coffee is a popular beverage enjoyed by many. Coffee products include decaffeinated coffee, which is produced by various processes. In practice, the caffeine is removed from the green coffee before roasting. Manufacturers of decaffeinated coffee take special care to maintain optimal sensory properties, as various changes in color, aroma, and composition occur when coffee is decaffeinated. Coffee is a rich source of caffeine, which can make up as much as 3% of the dry weight, so effectively removing this alkaloid is a complex multi-step process. The most important step before any established method of decaffeination is the introduction of steam or steeping green coffee for the purpose of swelling the beans. We are familiar with the classic methods that use organic solvents such as ethyl acetate and dichloromethane for caffeine extraction. Decaffeination with organic solvents can be carried out in a direct or indirect way. When organic solvents are used, it is important that no toxic solvent residues are present in the final product. Several methods of decaffeination with water have also been developed, in which other water-soluble components of coffee are extracted in addition to caffeine, which must be returned to the coffee in the final steps of the process. The most advanced method, which changes the composition of the coffee the least, is the extraction of caffeine with supercritical CO2. The major limitation of this method is its high cost. Decaffeination processes using biological methods are also under development, although the sensitivity of microorganisms and enzymes to various factors is a significant limitation. For this type of decaffeination process only a few microorganisms, which must tolerate caffeine, are appropriate.
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