Characterization of Stabilized and Unstabilized Beers

Abstract

The preparation and properties of polyvinylpolypyrrolidone (PVPP) and silica gel and the mechanisms by which they stabilize beer are discussed. In stabilized beer, chill stability was associated with lower protein sensitivity to precipitation with tannins. Approximately 60% of the proteoses were of low molecular weight (<10,000 daltons). The most acidic of these proteoses were the least stable in solution, being precipitated from beer by cold treatment and adsorbents.

Beer–The Importance of Colloidal Stability (Non-Biological Haze)

“…Permanent (irreversible) ( Figure 3)-protein + polyphenol; haze active (HA) proteins found in beer originate from barley's hordein protein fraction. HA-display a high affinity for polyphenols (PPs) and easily form haze [38]. Permanent haze can be caused by Reference [29]: Chill and permanent haze are a result of reversible interactions between high molecular weight (HMW) polypeptides (hordein) and polyphenols (malt and hops).…”

“…Covalent attachment (permanent haze) is preceded by ionic, hydrophobic, and hydrogen bonding causing chill haze. Polymerization of polyphenols may lead to covalent attachment with phenolic residues of amino acids in the polypeptide chain [38].…”