Process for the quasi-continuous decaffeination of raw coffee

A process for decaffeinating raw coffee beans by selective extraction of caffeine contained therein by means of a solvent that is liquid under ambient conditions, comprising the steps of:

• (a) extracting the caffeine from the raw coffee beans for a period of between one to several hours by means of a liquid solvent that is comprised of water and that has been saturated with a gas or gas mixture which has such thermodynamic characteristics that it diffuses in significant concentrations into the cells of the raw coffee beans which are filled with a and aqueous caffeine solution, said extraction being carried out at a temperature of between about 20.degree. C. to 110.degree. C. and a pressure of between about 30 bar and 300 bar to provide a charged liquid phase;
• (b) abruptly or within a few minutes reducing the pressure to between about 1 bar and about 10 bar to expand the raw coffee beans;
• (c) rinsing the expanded raw coffee beans in the liquid solvent for a period of between a few minutes to two hours;
• (d) drying the expanded raw coffee beans to reduce the water content thereof to that required for a subsequent roasting process and provide decaffeinated and pre-dried raw coffee beans;
• (e) roasting the decaffeinated and pre-dried raw coffee beans;
• (f) selectively separating the caffeine from the charged liquid solvent in a separate succeeding cycle by means of supercritical CO.sub.2 and recovering the caffeine in pure crystalline form;
• and
• (g) reusing the decaffeinated pressurized solvent, to replace CO.sub.2 losses occurring during caffeine extracting in step (a), as solvent for the extraction of caffeine and for rinsing.