The "acid gel" and "alkaline sol" methods of producing silica gels for use in the stabilisation of beer are described and their respective advantages and disadvantages discussed. A number of treatments can be applied to modify the properties of silica gels in order to cope with problems arising from the characteristics of particular beers. It may also be possible to incorporate oxygen scavenger molecules into the gel particles in order to enhance the protection of the beer against staling. The recent development of silica gel filter aids, which have physical properties similar to those of traditional filter aids such as kieselguhr but are less hazardous to personnel, less abrasive (and therefore do not inflict so much wear and tear on equipment) and easier to dispose of after use, besides having the same stabilisation properties as ordinary silica gels, is described with reference to trials conducted at two breweries, which indicated that such filter aids offer a practical alternative to kieselguhr, perlite, etc., with possible advantages in both reduced processing costs and improved beer flavour stability.
Keywords : beer filter aid filtration silica gel stabilisation