Effect of the Removal of Sensitive Proteins and Proanthocyanidins on the Colloidal Stability of Lager Beer

Abstract

Nine different trial beers were produced on a pilot scale from a common feedstock by using, either singly or in combination, three dosage rates (0, 15, and 30 g/hl) of polyvinylpolypyrrolidone (PVPP) and three dosage rates (0, 100, and 200 g/hl) of silica hydrogel (SHG). The colloidal stabilities of the beers were assessed by three forcing tests and by storage under simulated trade conditions. Colloidal stability varied widely but was greatest for beers dosed at the higher dosage rates with both SHG and PVPP. The data obtained were used to construct a model for predicting economical dosage rates compatible with a given stability specification. Suitable stabilization regimes included dosage with PVPP at 25 g/hl, dosage with SHG at 125 g/hl, or combined dosage with PVPP and SHG at 15 and 50 g/h1, respectively. Treatments with SHG diminished the contents of sensitive proteins in beers, whereas PVPP treatments decreased the polyphenol content. Dimeric proanthocyanidins were measured by direct-injection high-performance liquid chromatography, using an electrochemical detector. Other assays for polyphenols included less specific colorimetric and turbidometric methods. A close relationship was found between the rates of chill haze development in the nine beers and the products of their assay values for sensitive proteins and dimeric proanthocyanidins.