Absolute filters, cartridge filtration

Regarding water filtration procedures first, prefilters should be provided to prevent large particulates from entering the system and microfiltration to remove bacteria. Prefilters are usually the replaceable cartridge type with porosities ranging as high as 25 pm. Microfiltration follows and is generally accomplished with 0.2-pm absolute filters, which will remove most bacteria. 

In regard to filtration, recent advances in the brewing industries must also be referred to briefly. Absolute filters such as Millipore in cartridges are now in use for the cell separation from the brewery product to avoid the after effect of heat sterilization. 

Filtration can be distinguished in two types (1) absolute and (2) depth. In absolute filtration a steel or plastic screen, cartridge, or paper filter removes particles from the oil. These filters have certain porosity and most of them retain particles down to 5 pm, when used for passive filtration [72]. If diato-maceous earth or other absorbents are used, they are mixed with the oil in the fryer at the end of the day and/or shift and the suspension is pumped through the filter and circulated through the filter and back into the fryer until a filter bed is established and the fryer is free of fines and particulates. Filter media suppliers recommend a dose between 0.1% and 2.0%, by weight on the frying medium [8]. 

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