Beer clarification by microfiltration - product quality control and fractionation of particles and macromolecules

Beer clarification by microfiltration demands a finely balanced retention of colloidal particulates (yeast cells, chill haze flocs, etc.) and transmission of sol. macromols. including carbohydrates, proteins, flavor, and color compds. which give the "whole some" quality of a beer. The required porous transmission of these macromol. species led to an unavoidable, complex and dynamic in-pore membrane fouling in terms of fouling constituents, formation, structure and kinetics, which are the main obstacles in obtaining an economically viable flux and consistency in permeate quality. This exptl. study was carried out with the aims of understanding the dynamic interrelation between flux, fouling and system selectivity during a cross-flow beer microfiltration process so that an effective operating strategy for flux optimization could be formulated in conjunction with the parallel objective of good product (permeate) quality control. Tubular ceramic membranes (Ceramem) with nominal pore diams. of 0.2, 0.5, and 1.3 micro m were used. Simultaneous measurement of flux and permeate qualities, such as sp. gr. and chill haze level enabled identification of the effect of anti-fouling techniques, such as back-flushing on transmission of essential beer components and on the filtered beer quality. The exptl. evidence lead to an understanding that the drastic flux enhancement achieved by employing back-flushing at reversed membrane morphol. was assocd. with enhanced solute transmission which could, without careful control, upset a balanced transmission of essential beer components and the retention of unwanted "chill haze" components. Further operating parameters and varying system configurations were investigated over their effect on both flux performance and system selectivity. These include membrane pore size, filtration temp., and the addn. of an amorphous silica particles as coagulation agent for hydrophilic proteins. [on SciFinder (R)]