Towards a Kieselguhr- and PVPP-Free Clarification and Stabilization Process of Rough Beer at Room-Temperature Conditions.

Unlabelled: In this work, the main constraint (that is, beer chilling and chill haze removing) of the current beer conditioning techniques using Kieselguhr filtration and Polyvinylpolypyrrolidone (PVPP) treatment was overcome by developing a novel higher-throughput conditioning process, operating at room temperatures with no use of filter aids. The effect of filtration temperature (T ) in the range of 0 to 40 °C on the hydraulic permeability of ceramic hollow-fiber (HF) membranes with nominal pore size of 0.2 to 1.4 μm, as well as on their limiting permeation flux (J ) when feeding precentrifuged rough beer, was preliminarily assessed. When using the 1.4-μm HF membrane operating at T ≥ 20 °C, it was possible to enhance the average permeation flux at values (676 to 1844 L/m /h), noticeably higher than those (250 to 500 L/m /h) characteristics of conventional powder filtration. Despite its acceptable permanent haze, the resulting beer permeate still exhibited colloidal instability. By resorting to the commercial enzyme preparation Brewers Clarex® before beer clarification, it was possible to significantly improve its colloidal stability as measured using a number of European Brewing Convention forcing tests, especially with respect to that of precentrifuged rough beer by itself. By combining the above enzymatic treatment with membrane clarification at 30 °C across the ceramic 1.4-μm HF membrane module, it was possible to limit the haze development due to chilling, sensitive proteins, and alcohol addition to as low as 0.78, 4.1, and 4.0 EBC-U, respectively, the enzymatic treatment being by far more effective than that using PVPP.

Practical Application: A novel Kieselguhr- and PVPP-free rough beer conditioning process at room temperatures was set up. By submitting precentrifuged rough beer to commercial preparation Brewers Clarex ® and then to membrane clarification at 30 °C across a ceramic 1.4-μm hollow-fiber membrane module, it was possible to obtain a clear and stable beer with a throughput (1306 ± 72 L/m /h) by far higher than that (250 to 500 L/m /h) characterizing the current powder filters. The haze development due to chilling, sensitive proteins, and alcohol adding was by far lower than that observed when microfiltering PVPP-pretreated rough beer.