Method for decaffeinating coffee materials including a reverse osmosis permeate recycle

摘要

An improved method for extracting caffeine from a coffee material, preferably raw coffee solids, with an extractant comprising supercritical carbon dioxide. Caffeine is continuously absorbed from the extractant with an aqueous wash solution in an absorber. This wash solution is continuously treated by reverse osmosis to form a caffeine-containing retentate stream and a permeate stream containing dissolved solids but substantially no caffeine. The permeate stream is recycled and used as wash water in the absorber or is used to prehydrate solid coffee materials, or both. The permeate stream comprises acidic dissolved solids.