Concentrate Plants for the Fruit and Vegetable Industry GEA Process Engineering GEA Wiegand

Evaporation technology is a process of separating substances by means of thermal energy. The concentrated liquid which is still pump­ ble usually is the desired final product. Evaporation might a also aim at recovering the volatile constituent as in the case of the recovery of solvents and aroma. In the beverage industry, a frequently used process is evaporation under vacuum. 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...

Selection of evaporator types and plant designs The concentration of fruit juice in evaporators occupies a central position in the juice industry. Among the different types of evaporators, falling film evaporators are particularly suitable for the production of fruit juice con­ entrate due to their safe and efficient operation. The c necessary high final concentrations which depend on type of fruit, degree of ripeness, juice production method, pretreatment and fiber and pulp proportion, can be reached in this way. In GEA Wiegand falling film evaporators, the juice to be evaporated is distributed...

A larger total temperature range and smaller temperature differences in the falling film effects ensure efficient multiple-effect operation with a low heating steam and cooling water consumption and a high standard of product quality. The relatively large cross-sections in the heat exchanger tubes of the preheaters and in the heating tubes of the evaporation effects make it possible to also evaporate products that contain fibres and pulp. Falling film evaporators also show a stable operating behaviour at reduced load and with different products. As the time of product flowing through the plant...

5-effect falling film evaporation plant, directly heated, with aroma recovery system (DIFFAR), concentrate cooling system and fining outlet, for apple juice 1-5 calandrias B2 clear juice concentrate 6 condenser C aroma 7-12 preheaters C1 live steam condensate 13,14 feed tanks C2 vapour condensate 15,16 plate condensers D live steam 17 aroma recovery system E deaeration A1 cloudy juice feed EW chilled water A2 clear juice feed KW cooling water B1 cloudy juice for W water intermediate treatment For higher evaporation rates, the cloudy juice is preconcentrated in an independent pre-evaporator, and...

during concentration and, if these flavours are stored at cool temperatures, separate from the de-aromatized fruit juice concentrate, undesired conversion with juice constituents is practically not possible. In this way, the concentrated flavours (aroma concentrate) can be preserved for a long period of time. If the aroma concentrate is re-added when the juice is being rediluted, the typical flavour of the fresh juice can be restored almost completely. Each flavour consists of a number of constituents that more or less differ in quantity, solubility and boiling points. The vapour quantity to...

6-effect falling film evaporation plant as pre-evaporator with aroma recovery system; evaporation rate: 24,350 kg/h; the finisher is designed as 5-effect plant B cloudy juice intermediate 1-6 calandrias concentrate 7 condenser C aroma 8-13 preheaters C1 live steam condensate 14 feed tank C2 vapour condensate 15 aroma column D live steam 16 gas cooler E deaeration 17 aroma cooler EW chilled water 18 aroma scrubber KW cooling water A cloudy juice feed W water Diffusion-assisted aroma rectification (DIFFAR) This process is based on aroma concentration by means of partial condensation of the vapours...

Prior to the actual concentration process, the juice is preheated and is heated to pasteurization temperature. It is essential that the residence times of the product are as short as possible in order to maintain the quality of the juice to a large extent. The temperature profile is chosen in such a way that the enzymes splitting pectin are inactivated and that microorganisms are ex­ inguished to a large extent in order to t reach stability of the cloudy juice and to prevent the formation of alcohol caused by the fermentation of sugar. After heating, the juice is evaporated to 62 – 63 % DS in...

Pectin For the production of pectin, the dried peels of e. g. apples and citrus fruit are ground and conveyed to an extraction system. The raw extract is separated from the pomace by means of belt press filters or in decanters and separators and is clarified. After concentration and cooling, pure pectin is recovered by the precipitation of alcohol. The alcohol is recovered and the remaining vinasses is treated in a combined distillation/evaporation plant. GEA Wiegand uses falling film evaporation plants equipped with mechanical vapour recompressors for the concentration of pectin. The falling...

Control concepts Depending on the technical requirements and the customers‘ specific requests GEA Wiegand evaporation plants are equipped with the relevant measuring and control equipment – from the simple conventional control system to the PLC* system. Manual operation The plant is operated and monitored by means of local measuring instruments and manually actuated valves and fittings. Semi-automatic process control The most important process parameters such as steam pressure, vacuum, product supply and final concentration are maintained by means of compact controllers or by a PLC system (programmable...

Research and development In many cases, tests are necessary for determining the data on which to base the plant design and for studying the behaviour of the product during evaporation. The objective of the tests is to define the best operating con-ditions, to determine the most suitable type of evaporator and to produce con­ entrate and distillate samples. c The GEA Wiegand R & D Centre is equipped with modern laboratory equip­ ent and test m plants and is therefore optimally suited for analyses in the fields of evaporation tech­ ology n and distillation technology. GEA Wiegand has several test...