28. Surface forces and their effect on lautering

J. E. ENGSTLE (1), P. Först (1); (1) Technische Universität München, Chair of Process Engineering of Disperse Systems, Freising, Germany

Brewhouse Operations II
Friday, October 9
10:00–11:45 a.m.
River Terrace 2

Filtration performance of fine grain suspensions highly depends on surface force effects. Those forces (mostly electrostatic and van der Waals forces) can lead to changes in the structure of filter cakes. A higher porosity and, therefore, a higher permeability can be achieved, as well as a shift in compression behavior. Consequently measurements of filter cake resistance as a function of pH value or zeta potential are widely used in the filtration industry. In brewing science this perspective is mostly unfamiliar. Since the upper layer of the spent grain cake consists mainly of proteins and is the limiting factor for lautering performance, it is very likely that this layer is influenced by surface effects. This offers great potential for further improvements in the lautering process. Measurements are carried out to show the influence of surface effects depending on pH value and temperature on fine spent grain cakes. A filter cell is used to detect filter cake resistance. It can be shown that a higher temperature results in better cake permeability and that the pH optimum is 4. This explains both why acidification of mash results in faster lautering times and that a higher temperature lautering is not only beneficial due to a lower wort viscosity but due to structural changes in the spent grain cake.

Jörg Engstle studied brewing and beverage technology in Weihenstephan. He graduated in 2012 with an engineering diploma. Since then he has been working as a doctoral candidate at the Chair of Process Engineering of Disperse Systems in Weihenstephan. His field of work covers the mash separation process, mostly via lauter tun. He also works on procedural characterization of different hop products to enable a faster matching of dry-hopping equipment to different hop styles, types, and products.

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