Process for the quasi-continuous decaffeination of raw coffee

摘要

A process for decaffeinating raw coffee by selective extraction of the caffeine by means of a solvent that is liquid under normal conditions. Raw coffee beans are extracted for between one and several hours by means of a liquid solvent that is comprised of water and that has been saturated with carbon dioxide or other suitable gas or gas mixture at a temperature of between about 20 DEG C. and 110 DEG C. and a pressure of between about 30 bar and 300 bar to provide a charged liquid solvent. The pressure is reduced abruptly or within a few minutes to a pressure between about 1 bar and 10 bar to expand the raw coffee beans. The expanded raw coffee beans are rinsed in the liquid solvent for a period of between a few minutes and two hours. The expanded raw coffee beans are dried to reduce the water content to that required for subsequent roasting, and the decaffeinated and pre-dried raw coffee beans are then roasted, after which the caffeine is selectively separated from the charged liquid solvent and the caffeine is recovered in pure crystalline form.