Novel cold sterilization and stabilization process applied to a pale lager

Abstract

In this work, the crossflow microfiltration (CFMF) performance of different lots of a rough pale lager, produced in the industrial brewery Birra Peroni Srl (Rome, Italy), was assessed in a bench-top plant, equipped with a 0.8-μm ceramic tubular membrane module, under constant crossflow velocity (6ms−1), transmembrane pressure difference (3.74bar), temperature (10°C), and periodic CO2 backflushing. The average permeation flux increased from (86±8) to (252±21) Lm−2h−1, provided that the rough beer was fed as such or pre-centrifuged to minimize the fouling contribution of yeast cells and aggregates, respectively. In both cases, the permeate turbidity at 20°C fulfilled that recommended by the European Brewery Convention standards; but, as expected, the chill haze at 0°C was quite higher than 0.6 EBC unit. A preliminary stabilization of pre-centrifuged beer using 0.5gL−1 of regenerable polyvinylpolypyrrolidone (PVPP) at 0°C for 24h allowed the permeate chill haze to be reduced to (0.63±0.22) EBC unit; but the average permeation flux fell to (161±21)Lm−2h−1. By removing the residual PVPP particles from stabilized beer using a 2.7-μm filter before CFMF, it was possible not only to re-enhance the average permeation flux up to 337Lm−2h−1 (this value being in line with those achievable with conventional DE-filters), but also to obtain a chill haze-free permeate ready for aseptically packaging.By referring to an industrial plant capacity of 2×106hL of lager beer, the estimated overall operating costs and global warming potential for this novel combined pale lager clarification and PVPP stabilization procedure reduced to about the 30% of those associated with the current industrial DE-filtration and regenerable PVPP stabilization procedures.