Novel Procedure for Lager Beer Clarification and Stabilization Using Sequential Enzymatic, Centrifugal, Regenerable PVPP and Crossflow Microfiltration Processing

Abstract

In this work, the crossflow microfiltration (CFMF) performance of different lots of lager beer, produced in a pilot scale at the Italian Brewing Research Centre (CERB, Perugia, Italy), was assessed in a bench-top plant, equipped with a 0.8-μm ceramic tubular membrane module, under constant crossflow velocity of 6 m s−1, transmembrane pressure difference of 3.74 bar, temperature of ~10 °C, and periodic CO2 backflushing. By feeding different beer samples (i.e., as such, precentrifuged (C), or pretreated with a commercial enzyme preparation to degrade the original arabinoxylans and β-glucans and then centrifuged (EC) to minimize the fouling contribution of yeast cells, aggregates, and polysaccharides), it was possible to increase the average permeation flux (expressed as mean value ± standard deviation) from 112 ± 13 to 199 ± 17 or 330 ± 22 L m−2 h−1, respectively. Only when using the EC-pretreated beer specimens, the permeate turbidity at 20 °C approached the limiting one (<0.6 EBC unit) recommended by the European Brewery Convention standards. As expected, the permeate chill haze at 0 °C was generally higher than the above haze target. By submitting EC-pretreated beer seeded with 0.5 g L−1 of regenerable polyvinylpolypyrrolidone (PVPP) to CFMF, it was possible to reduce the initial total polyphenol content by 30 % and permeate chill haze to 0.60 ± 0.01 EBC unit, but the average permeation flux fell to 84 ± 4 L m−2 h−1. By performing sequentially EC pretreatments, PVPP stabilization, cartridge filtration, and CFMF, it was possible not only to re-enhance the average permeation flux at about 230 L m−2 h−1 near to those achievable with DE filters, but also to obtain a chill haze-free permeate ready for aseptic packaging.