Cider Perry Pre-Filters
The fundamental purpose of cider pre-filtration is to limit the cost of final filtration by removing the haze and minimizing contaminants that can reduce the working life of the final filter. The pre-filter should be capable of removing particles left over from upstream processing (crystals, DE, fining agents), removing colloids and reducing the typical cider spoilage organisms like yeast and bacteria in order to extend the life of the final membrane filters and to prevent off-flavors and post-bottling re-fermentation.
A cider pre-filter should not only have a high dirt holding capacity, but also be easily regenerated in situ while remaining inert to the properties of cider. It is recommended to install a cider pre-filter with an absolute particulate rating of 0.8 to 1 micron directly upstream of the final filter to extend the life of the final filter (an absolute filter is one with a removal efficiency of greater than β-5000).
Given that a cider pre-filter is typically installed in-line directly upstream of the final filters and filling machine, it must be able to withstand the same sanitization and cleaning regimes as the final filter and possibly those of the filler itself.