When the coffee extract is discharged from the extractor, it has a solids content of 6-8 % TS, depending on how the extraction and aroma recovery is performed.

Concentrate Evaporation
To obtain a first-class instant coffee powder, it is necessary to concentrate the extract (without the aroma fraction). This is typically done in a falling-film evaporator with 2-4 stages to save energy, either in form of steam in a TVR evaporator or electricity in an MVR evaporator. In both cases the evaporator is operated under vacuum at low temperature. Hereby a very lenient treatment of the extract is obtained, and deterioration of the coffee taste is avoided. In combination with the aroma recovery system an excellent concentrate with all the valuable aroma and taste elements pre-served is produced.

If the concentrate is to be spray dried, it is possible to increase the solids content to approx. 50 % TS. For freeze dried coffee the solids content is approx. 45 %.

Freeze Concentration
It is also possible to use freeze concentration, where the water is removed as ice crystals. This process operates at temperatures below the freezing point and obviously all the aroma is maintained.

Membrane Filtration
The aroma fraction of the extract can be preconcentrated when it is discharged from the aroma recovery plant by reverse osmosis in a membrane filtration system. This slightly changes the taste profile, which is an advantage for some coffees and in some markets.
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