Fruit juice membrane filtration

MEMBRANE FILTRATION. Membrane filter cartridges are seldom used in fruit juice technology, as hot-filling is the common practice and prior membrane filtration is therefore unnecessary. These filters can only be used after fine filtration, as otherwise the membrane is immediately clogged up. 

The capacity can be increased further by reducing the viscosity of the liquid to be filtered. This can be achieved by treating fruit juices enzymatically and also by increasing the filtration temperature. The ideal temperature is determined by the temperature resistance of the membrane material and on the other hand by the fact that it must not impair the quality of the product. 

An editorial in "Filtration and Separation" [59] highlights the reluctance of the beer brewers to change over from kieselguhr filtration to membranes, but judges that the examples of fruit juice and wine production show good market prospects. 

Fruit juice clarification by pectinases and cellulases is another interesting application. In the conventional process after the enzymatic reaction in the pulp treatment step takes place, filtration over diatomaceous earth follows. This filtration-type process produces a lot of solid waste, and results in costly enzyme loss. MBR are appropriate for such application either for enzyme recovery and recycle or in the form of a more compact CMR type system, with the biocatalyst immobilized on the membrane itself [4.58]. 

Membrane operations have been extensively used in the food industry because they require less manpower, are more efficient, and have a shorter processing time than traditional separation techniqnes, so operational costs are considerably lower than traditional processes [105], For instance, membrane separation processes to clarify and concentrate liquids are less costly than conventional filtration and vacuum evaporation, justifying their application in this field [106]. The primary applications of membranes in the food industry are in the beverage (wine, beer, fruit juices, etc.) and dairy (whey protein concentration, milk protein standardization, etc.), processing industries in the processing of egg prodncts, to a lesser extent, and in water purification. 

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