ATPGroup Brewing Catalog 2021-2022 - Catalog - Page 24
CLARIFIERS & STABILIZERS
SILICA
Silica stabilizer products are amorphous silica particles created by the acid treatment of silicon dioxide to change the surface
chemistry of the particle to expose hydroxyl (silanol) groups. Silanol groups are extremely selective in binding sensitive proteins
— thus reducing the potential for haze formation. The availability and number of silanol groups determines the effectiveness of
certain silica products.
Silicasols are granules with little porosity and silanol groups on the surface, suspended in aqueous solutions. Hydrogels and
xerogels are milled porous granular silica products with a greater number of exposed silanol groups (more groups = more effective).
Optimum protein adsorption is attained with silicas having maximum surface area in pores in the range of 3–12 nm. The solids
content of the silica, the particle size and number of accessible hydroxyl groups determine adsorption capacity. Thus, on a gramfor-gram basis, for a given pore structure silica xerogels provide greater protein adsorption than hydrogels.
Proline Rich “Sensitive Protein”
OH OH
OH
OH
OH
OH
OH
OH
HO
HO
HO
OH
OH
OH
OH
OH
OH
OH
HO
HO
OH
HO
HO
OH
OH
OH
Pore in Surface of Silica Particle
Silica Surface with Exposed Silanol Groups
ENZYMES
Enzymes have been used for many years to control haze in finished beers. The enzymes used are broadly classified as proteinattacking (proteases) or starch-attacking (amylases). Enzymatic haze stabilization is a great option for brewers wishing to move
away from traditional stabilizers such as silicas, PVPP, or gallotannins.
Amylases
These enzymes reduce excess starch in beers that can cause haze and can be controlled enzymatically post filtration. Amylases
are not commonly used today. The risk is the conversion of the starch into excess glucose, which in turn can be metabolized
even further by any residual yeast or bacteria present after the beer has been packaged. The product should be pasteurized to
inactivate the enzyme and kill any residual yeast or bacteria.
Proteases
These enzymes attack proteins and are the most commonly used. Some such as papain are broad spectrum and will produce
brilliant beer but at the same time destroy all the foam-positive proteins. More specific proteases such proline-specific endoproteases and acid-stable exo-endo proteases target protein haze precursors.
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