Is Decaffeinated Coffee Bad For You?
Which is the most prevalent form of processing decaffeinated coffee presently used by the coffee industry? Decaffeination is performed prior to roasting. The most common and least costly caffeine extraction methods in the coffee industry basically employ an organic solvent such as dichloromethane or ethyl acetate, associated with the use of water/vapour prior to and after extraction for washing and opening of the pores. Water alone has alternatively and increasingly been used to replace organic solvents in the process, especially in the United States and Europe. Beans are then dried until they reach the moisture similar to that prior to processing. At the end of the process, caffeine content is usually reduced from 1–2 g% to 0.02–0.3 g% (Balyaya and Clifford, 1995; Farah et al., 2006a; Toci et al., 2006). The caffeine extracted from the green beans may be recovered and commercialised for production of cola types of beverage, pharmaceutical drugs and other purposes. During the decaffeination process, losses of key flavour components generally occur (Silvarola et al., 2004), especially when using solvents that lack specificity, such as water. Different devices have been created in order to return the aromatic fraction lost during the caffeine extraction. Alternatively, coffee aroma may be added to the decaffeinated product.
There is a general concern regarding the consumption of residual methylene chloride in the coffee beverage after decaffeination process. Considering that the boiling point of this solvent is 40° C and that coffee goes through temperatures around 70° C for solvent volatilisation, green coffee beans should not contain significant amounts of the solvent. In addition, roasting temperatures (commonly 210–230° C) are high enough to allow volatilisation of any remaining amount of dichloromethane in coffee. The US FDA (Food and Drug Administration) allows up to 10 ppm in roasted coffee, while the European Union allows up to 3 ppm. In most cases, according to industry reports, the residual concentration of dichloromethane is 100× lower (FDA, 2006). A method that is more efficient for maintaining the original flavour of regular coffee, although costly, is the supercritical carbon dioxide method, in which carbon dioxide is used at high pressure and temperature to replace the organic solvents (Farah et al., 2006a). Credit: A summary from published paper Functional and Speciality Beverage Technology 2009 ScienceDirect.
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