Method for decaffeinating coffee with a supercritical fluid

Claim 1

A method of extracting caffeine from green coffee comprising: (a) continuously feeding essentially caffeine-free supercritical carbon dioxide containing non-caffeine solids and saturated with water to the lower end of an elongate, substantially vertical extraction vessel containing green coffee beans having a moisture content of 25-50% by weight, continuously countercurrently contacting the supercritical carbon dioxide and the green coffee beans in said extraction vessel to affect extraction of caffeine from the coffee into the supercritical carbon dioxide, and continuously withdrawing supercritical carbon dioxide containing caffeine and non-caffeine solids from the upper end of the extraction vessel; (b) discharging a portion of the coffee beans in said vessel from the lower end of the extraction vessel, the discharged portion comprising decaffeinated coffee beans; (c) moving the remaining coffee beans downwardly in the extraction vessel to an extent corresponding substantially to the amound of decaffeinated coffee beans discharged from the extraction vessel; (d) introducing moist green coffee beans having a moisture content of 25-50% into the upper end of said extraction vessel in an amount corresponding substantially to the amount of decaffeinated coffee beans discharged from the extraction vessel; (e) maintaining the temperature in the extraction vessel at from 80°-140° C.; (f) feeding the supercritical carbon dioxide containing caffeine and non-caffeine solids withdrawn from the upper end of the extraction vessel to an absorber; (g) continuously countercurrently contacting the supercritical carbon dioxide containing caffeine and non-caffeine solids with water in the absorber at a temperature and pressure substantially the same as in the extraction vessel to extract substantially all of the caffeine contained in the supercritical carbon dioxide but extracting no appreciable amount of said non-caffeine solids therefrom; (h) withdrawing caffeine-laden water from the absorber; (i) withdrawing substantially caffeine-free supercritical carbon dioxide containing non-caffeine solids from said absorber; (j) recycling the substantially caffeine-free supercritical carbon dioxide containing non-caffeine solids to the lower end of the extraction vessel as required by step (a); and (k) periodically repeating steps (b), (c) and (d) while carrying out steps (a) and (e) through (j) to effect extraction of caffeine from said green coffee beans.

Claim 2

A method of extracting caffeine from green coffee comprising: (a) continuously feeding essentially caffeine-free supercritical carbon dioxide containing non-caffeine solids and saturated with water to the lower end of an elongate, substantially vertical extraction vessel containing green coffee beans having a moisture content of 25-50% by weight, continuously countercurrently contacting the supercritical carbon dioxide and the green coffee beans in said extraction vessel to affect extraction of caffeine from the coffee into the supercritical carbon dioxide, and continuously withdrawing supercritical carbon dioxide containing caffeine and non-caffeine solids from the upper end of the extraction vessel; (b) discharging a portion of the coffee beans in said vessel from the lower end of the extraction vessel, the discharged portion comprising decaffeinated coffee beans; (c) moving the remaining coffee beans downwardly in the extraction vessel to an extent corresponding substantially to the amound of decaffeinated coffee beans discharged from the extraction vessel; (d) introducing moist green coffee beans having a moisture content of 25-50% into the upper end of said extraction vessel in an amount corresponding substantially to the amount of decaffeinated coffee beans discharged from the extraction vessel; (e) maintaining the temperature in the extraction vessel at from 80°-140° C.; (f) feeding the supercritical carbon dioxide containing caffeine and non-caffeine solids withdrawn from the upper end of the extraction vessel to an absorber; (g) continuously countercurrently contacting the supercritical carbon dioxide containing caffeine and non-caffeine solids with water in the absorber at a temperature and pressure substantially the same as in the extraction vessel to extract substantially all of the caffeine contained in the supercritical carbon dioxide but extracting no appreciable amount of said non-caffeine solids therefrom; (h) withdrawing caffeine-laden water from the absorber; (i) withdrawing substantially caffeine-free supercritical carbon dioxide containing non-caffeine solids from said absorber; (j) recycling the substantially caffeine-free supercritical carbon dioxide containing non-caffeine solids to the lower end of the extraction vessel as required by step (a); and (k) periodically repeating steps (b), (c) and (d) while carrying out steps (a) and (e) through (j) to effect extraction of caffeine from said green coffee beans.