When we make a cup of instant coffee we are actually brewing it for the second time. This is because the manufacture begins with making coffee. Roasted and ground coffee beans are boiled in pots, just as they would be for mocha or Turkish coffee, only much more intensely. When most of the water has evaporated and the coffee grounds have been removed, the thick coffee solution that remains is dried. There are two ways of doing this: spray-drying and freeze-drying. With spray-drying, the wet coffee solution is sprayed through a fine nozzle into a drying tower, from the bottom of which hot, dry air rises. The remaining water evaporates and the instant coffee powder collects at the bottom of the tower. With freeze-during, the coffee extract is chilled to -40°C in a matter of minutes. The slabs of iced coffee then pass into a warm vacuum, where sublimation takes place the solid ice turns straight into water vapor, bypassing the liquid stage. Again, all that is left behind is the familiar dry, water-soluble powder.
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