PQ's adsorbent gels are specially designed silica gels, known worldwide under the flagship name BRITESORB®. The building unit of silica gels is silicon dioxide, SiO2, the same material that occurs in nature as sand. The difference between sand and silica gel is that sand is crystalline and non-porous, whereas silica gels are amorphous (non-crystalline) and highly porous. By changing sand into a porous material, we create an enormous internal surface area on which certain materials are selectively adsorbed. By carefully controlling the size and surface characteristics of the pores, we can make a silica gel adsorb only those components we want to remove.
Beer stabilization is one of the applications in which BRITESORB® adsorbents are effectively used.
Beer contains various proteins (polypeptides) and tannins (polyphenols) that can slowly react during shelf storage to develop a colloidal complex. This complex becomes insoluble at cold temperatures at which beer is stored and consumed. The result is the formation of an undesirable turbidity known as chill haze.
Haze formation is accelerated by oxidation of beer during processing, by the introduction of headspace air during packaging, by elevated storage temperatures, and by the presence of heavy metals such as copper and iron.
Because the chill haze precursors cannot be filtered out of the beers, breweries use stabilizers to prevent the formation of haze in the first place. Commonly used stabilizers have included enzymes, tannic acids, polyvinylpolypyrrolidone (PVPP), and silica gels.
BRITESORB®beer stabilizers are highly porous silica gel particles that selectively adsorb proteins that naturally occur in beer. The proteins that cause chill haze will be adsorbed, while the proteins necessary for an attractive and stable head of foam will not be adsorbed. During filtration of beer, the silica gel will be completely removed. The result is a brilliant beverage that retains its clarity during extended shelf storage.
PQ’s BRITESORB® beer stabilizers can be divided into two categories: silica hydrogels and silica xerogels. Hydrogels contain a relatively high content of water (over 60%), while xerogels have low water content (typically less than 12%). Each BRITESORB® particle has pores of carefully controlled size and huge internal surface area. Hydrogels have the advantages of lower dusting and faster filtration, while xerogels have the advantages of effectiveness at shorter contact times, better microbiological stability, and higher activity on difficult-to-chillproof beers.
Hydrogels are preferably used by:
- breweries with buffer tanks before their filters
- breweries desiring longer filter cycle times
- breweries with no dust control equipment
Xerogels are preferably used by:
- breweries with automated operations, since xerogel is more easily handled as a flowing powder
- breweries using bulk handling, since xerogels can be stored without microbiological growth occurring
- breweries needing extra stability (e.g. for export)