Vacuum evaporation of fruit juice

EVAPORATION under vacuum is a frequently used process in the beverage industry. Freshly pressed fruit juice from stone, pomaceous and soft fruit, as well as juice from citrus and tropical fruit is concentrated and is in this way preserved. Before or during the evaporation process, volatile flavours are extracted from the thin juice, are recovered and are re-added to the fruit juice later on for intensifying the typical fruit taste.

The advantages of the evaporation of juice and the storage of concentrate are obvious:

Six to seven times the quantity can be stored in a storage tank under simplified storage conditions;

Concentrate can be preserved without being cooled due to its high sugar content;

Fluctuations in quantity and quality of different vintage can be balanced and adapted to the market situation;

Concentrate as commodity is easier to market; and

The transport of concentrate is simpler and cheaper.

Selection of evaporator types and plant concepts

The concentration of fruit juice in evaporators occupies a central position in the juice industry. Amongst the different types of evaporators, tube falling film evaporators are particularly suitable for the production of fruit juice concentrate due to their safe and efficient operation. The necessary high final concentrations, which depend on the type of fruit, degree of  ripeness, juice production method, pre-treatment, and the fibre and pulp proportion, can be reached in this way.

In GEA Wiegand falling film evaporators, the juice to be evaporated is distributed onto the upper tube sheet and onto the heating tubes by an especially developed distribution system. From this system, the product flows downwards in the heating tubes to the lower tube sheet as a thin film. The evaporated vapour (steam) flows downwards in the same direction and consequently accelerates the flowing of the film. This limits the period of residence, during which the juice to be evaporated is retained in the heating tube, to a few seconds.

The product flows tFemme