Studies on the effects of common process variables on the colloidal stability of beer

The effect of simple changes in process variables on the colloidal stabilit y 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 e ffect of storage time (up to six days) and storage temperature (0 and 4 deg reesC), before stabilization and filtration, on the resultant colloidal sta bility of the beers was examined. The results were used to optimize the sta bilization process with respect to sorbent dosage rate and beer storage tim e. 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 degreesC or months (28 days) at 18 degre esC. 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. Incr easing the storage temperature from 0 to 4 degreesC could be compensated fo r, in terms of measured colloidal shelf life, by increased stabilizer dosag e rate.