Process for the preparation of soluble coffee

A process for multi-stage extraction of ground roast coffee in which a soluble coffee is provided in an economically acceptable yield, having the original aroma of the starting roast coffee, and wherein off-flavours arising from the hydrolysis process are not longer present thus giving the soluble coffee a roast bean coffee quality which comprises the following stages:

• (a) ground roast coffee of a particle size of at most approximately 1.8 mm, which has been moistened to a water content of approximately 4 to 70 wt %, relative to the ground dry roast coffee, is treated in a percolator with a length/diameter ratio of approximately 3.2:1 to 0.9:1 with saturated steam at a pressure of approximately 0.1 to 1 bar and a temperature of approximately 30.degree. to 100.degree. C. for approximately 2 to 40 minutes, the steam loaded with coffee constituents is condensed at a temperature of approximately 0.degree. to 15.degree. C. to a condensate quantity of approximately 3 to 20 wt %, relative to the quantity of dry roast coffee used, and the condensate is obtained as aroma "a",
• (b) the coffee remaining from stage (a), freed from aroma "a", is subjected with extraction water to a primary extraction in a quantity of approximately 2 to 6 parts by weight per part by weight of dry starting roast coffee, at a temperature of approximately 20.degree. to 150.degree. C. and a pressure of approximately 5 to 100 bar with the aid of at least 2 percolators with a length/diameter ratio of approximately 3.2:1 to 0.9:1 for approximately 2 to 40 minutes per percolator and for an overall time of approximately 10 to 200 minutes, followed by pressure-relief to approximately 0.001 to 1 bar, the evaporated portion obtained by spontaneous partial evaporation of the extract is condensed at a temperature of approximately 0.degree. to 15.degree. C. and the condensate is obtained as aroma "b" and the non-evaporated portion as primary extract;
• (c) the coffee remaining from stage (b), freed from aroma "b" and from primary extract, is subjected with extraction water to a secondary extraction in a quantity of approximately 2 to 6 parts by weight per part by weight of dry starting roast coffee at a higher temperature than in stage (b) within a range of approximately 100.degree. to 215.degree. C. and at a pressure of approximately 5 to 100 bar with the aid of at least 2 percolators with a length/diameter ratio of approximately 3.2:1 to 0.9:1 for approximately 2 to 40 minutes per percolator and for an overall time of approximately 10 to 200 minutes, followed by pressure-relief to approximately 0.01 to 2 bar, the evaporated portion obtained by spontaneous partial evaporation of the extract is discarded, the non-evaporated portion is obtained as secondary extract;
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• (d) the extracts are concentrated, combined, mixed with aromas "a" and "b", and the obtained extract which has a concentration of about 35 to 55% is dried.