Decaffeination of aqueous extracts

A process for decaffeination of green coffee comprising the steps of:

• (a) extracting caffeine from green coffee beans by contacting the beans with a decaffeinated aqueous solution of green coffee to prepare an extract containing caffeine and other soluble components of green coffee and separating this extract from the green coffee beans now substantially freed of caffeine,
• (b) feeding said extract to above the uppermost plate of a perforated plate extraction column having a plurality of plates,
• (c) feeding supercritical carbon dioxide continuously to below the lowest plate of the said column at a velocity at which, foam, formed by intermixing of the green coffee extract and the supercritical carbon dioxide is broken by contact with a means for breaking foam comprising a porous extended solid surface placed above each perforated plate and extending across the column between successive plates,
• (d) withdrawing said supercritical carbon dioxide together with dissolved caffeine continuously from the top of the column to remove caffeine from the green coffee extract,
• (e) removing the aqueous green coffee extract, now substantially freed of caffeine, continuously from the bottom of the extraction column and recycling it to step (a) to decaffeinate additional green coffee beans,
• (f) maintaining the pressure within the said column at greater than about 330 bar,
• (g) maintaining the temperature within said column in the range of about 80.degree. to 100.degree. C.,
• (h) maintaining the concentration of green coffee extract in the column within the range of about 18 to 30 percent dissolved solids,
• (i) separating caffeine from the carbon dioxide exiting the top of the column and recycling carbon dioxide, substantially freed of caffeine, to below the lowest plate of the column.