Beer is the fifth most consumed beverage in the world after tea, carbonates, milk and coffee and it continues to be a popular drink. One of the important reasons is that beer is a drink with a pleasant flavor, an attractive color and clarity. To attain these characteristics, Membrane separation technology has become widely used in the food processing industry. The final filtration stage sets for a balance between allowing the passage of dissolved macromolecules that give the beer its flavor and functional properties while removing yeast cells and turbidity colloids and reducing the components that cause turbidity of the bottled beer. Moreover the potential of cross-flow microfiltration as a separation method for brewing is a subject of intensive …show more content…
The general effect of these phenomena, known as concentration polarization, is a rapid permeate flux decay during the early period of filtration, followed by a long and gradual flux decline towards a steady, or nearly-steady-state limit value. However, a more important aspect of concentration polarization phenomena, which has to be considered, is related to the physicochemical interactions of the accumulated material with the membrane. In this case, a fouling mechanism, such as adsorption on the membrane pore walls and pore plugging by the solute penetration occurs rather than the build-up of a particle cake layer at the interface (15). The direct consequence of this fully reversible concentration polarization is a resistance that arises from the osmotic pressure, which leads to a decrease in the driving force. However, the solute concentration, especially proteins, near the membrane interface can reach such high values that gel layer formation occurs. Gel layer formation is usually referred to as 'membrane fouling' and is irreversible or, at best, only partly Reversible (7). Figure 2 illustrated both of the