| 摘要 |
A process for the counter-current extraction of ground roasted coffee with water comprises moistening the coffee under an atmosphere of gas inert to the soluble coffee matter a pressure higher than the escape pressure of the gases contained in the dry coffee and extracting the coffee at the same pressure. Roasted coffee is poured into a bunker from which air is expelled by introducing carbon dioxide at the bottom. The coffee is then passed to and ground in an air-sealed mill and the ground coffee transferred by a screwconveyer in an air-tight conduit to one of a series of extraction vessels, the vessel being pressurized with carbon dioxide from a buffer vessel. Fresh water under pressure is passed via a measuring pump, through a steam heated heat exchanger to raise its temperature to 160 DEG C., and into the extraction vessel containing the most exhausted coffee. The first extract so produced is then passed in turn through other vessels containing partially exhausted coffee and finally into the vessel containing the freshly ground coffee. The temperature of the extracting liquid drops gradually from 160 DEG C. to 80 DEG C. as it passes through the series of vessels, temperature corrections, where necessary, being effected by means of heat exchangers sited in the conduits connecting the vessels. |
