Sterilization of Beer
Absolute sterility of the bottled beer is essential given the fact that bottles are shipped over long distances, subject to varying temperature regimes, and often remain on the shelf for fairly long periods. Traditionally sterility of beer was accomplished by pasteurizing the beer in the bottle after filling and crowning by a process known as tunnel pasteurization. Alternatively, the beer can be sterilized prior to packaging either by flash pasteurization or sterile filtration.
Flash pasteurization has not been widely used by breweries in North America (though it is very popular with the dairy and juice industries), but in recent years it has grown in popularity in bottling beer. Europe and Asia, on the other hand, has adopted this process extensively. There are many hundreds of such systems in existence, most of which are used for kegs, and some for bottles and cans. Tunnel pasteurization is most commonly used with small-pack beer, either bottles or cans.
Sterile filtration physically removes organisms from the beer as it passes through a cartridge membrane filter. It is essential the beer first undergo primary diatomaceous earth filtration and in some cases sheet pad filtration before it undergoes sterile cartridge membrane filtration.
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