[Progresses in the concentration of foodstuffs (author's transl)]

The article reports a description and a comparison of three concentration techniques: evaporation, freeze-concentration and reverse osmosis. The discussion is particularly concerned with the problems of aroma losses and retention and, for evaporation, the problems of heat damage and fouling. The increase in viscosity with concentration and the markedly non-newtonian behaviour of most food products are such that only evaporation allows to achieve high concentrations. The major progresses in evaporation plants and techniques are discussed in terms of heat transfer efficiency and residence time. Freeze-concentration and reverse osmosis are suitable for pre-concentration up to 30-35 10Brix of heat sensitive and aromarich products