Studies on the Effects of Common Process Variables on the Colloidal Stability of Beer

Abstract

The effect of simple changes in process variables on the colloidal stability of beer was examined. Lager beers were stabilized using silica hydrogel (SHG) at 25–125 g/hl or polyvinylpolypyrrolidone (PVPP) at 10–50 g/hl. The effect of storage time (up to six days) and storage temperature (0 and 4°C), before stabilization and filtration, on the resultant colloidal stability of the beers was examined. The results were used to optimize the stabilization process with respect to sorbent dosage rate and beer storage time. Haze precursors were measured using the standard rapid assays: tannoids, total polyphenols, total flavanols, sensitive proteins, and alcohol-chill haze. Colloidal shelf life was measured as the time taken to reach a total haze of 2 EBC units in weeks at 37°C or months (28 days) at 18°C. Colloidal shelf life was directly proportional to sorbent dosage rate for both SHG and PVPP. The rapid assays were poor predictors of beer shelf life but were effective monitors of the stabilization process. The optimum storage time examined for lager beer before filtration was three days. Increasing the storage temperature from 0 to 4°C could be compensated for, in terms of measured colloidal shelf life, by increased stabilizer dosage rate.