Beer Clarification by Novel Ceramic Hollow-Fiber Membranes: Effect of Pore Size on Product Quality.

Abstract

In this work, the crossflow microfiltration performance of rough beer samples was assessed using ceramic hollow-fiber (HF) membrane modules with a nominal pore size ranging from 0.2 to 1.4 μm. Under constant operating conditions (that is, transmembrane pressure difference, TMP = 2.35 bar; feed superficial velocity, vS = 2.5 m/s; temperature, T = 10°C), quite small steady-state permeation fluxes (J* ) of 32 or 37 L/m2 /h were achieved using the 0.2- or 0.5-μm symmetric membrane modules. Both permeates exhibited turbidity <1 EBC unit, but a significant reduction in density, viscosity, color, extract, and foam half-life with respect to their corresponding retentates. The 0.8-μm asymmetric membrane module might be selected, its corresponding permeate having quite a good turbidity and medium reduction in the aforementioned beer quality parameters. Moreover, it exhibited J* values of the same order of magnitude of those claimed for the polyethersulfone HF membrane modules currently commercialized. The 1.4-μm asymmetric membrane module yielded quite a high steady-state permeation flux (196 ± 38 L/m2 /h), and a minimum decline in permeate quality parameters, except for the high levels of turbidity at room temperature and chill haze. In the circumstances, such a membrane module might be regarded as a real valid alternative to conventional powder filters on condition that the resulting permeate were submitted to a final finishing step using 0.45- or 0.65-μm microbially rated membrane cartridges prior to aseptic bottling. A novel combined beer clarification process was thus outlined.