Tobias Teumer (1),
Frank-Jürgen Methner (2), Matthias Rädle (1); (1) University of Applied
Science, Mannheim, Germany; (2) Technische Universität Berlin, Berlin,
Germany
Analytical
Poster
In some steps of food engineering processes, particularly after
brewed beer gets filtered, unwanted reactions can take place in the
solution, such as coagulation or the appearance of other disperse phase
products. However, the filtered beer should be free of particles. After
filtration, beer haze can form through oxidation caused by insufficient
stabilization steps. Known coagulation processes are either pure protein
complexes or protein–phenol complexes, as well as oxalate precipitation
that results from other processes. To get a better understanding of
this formation process it is possible to make in-line measurements of
the refractive index of the disperse-phase, the particle size, and
concentration with high time resolution. Gluten is used in a solution
together with ethanol to analyze the protein precipitation that consists
in equal proportions of the amino acids glutelin and prolamin. Both
amino acids precipitate at a pH value between 4.2 und 5.2 at the
isoelectric point. In a second comparison study, oxalate precipitation
gets analyzed. First, a fast optical measuring technique with 2,300
measurements/second/channel is used with two different wavelengths, 450
nm and 650 nm, to observe particle growth. Second, a slow measuring
technique is developed with roughly 5 measurements/second to acquire a
full spectra in the visible range to determine particle growth.
Supported by mie theory calculations the necessary material values get
adjusted. Concentration and pH value interference with the particle
growth are shown and validated through light microscopy reference
measurements. With this forthcoming knowledge toward precipitation
reactions in beer, improved quality measurement equipment for the
brewery industry can be developed.
Tobias Teumer received a Dipl.Ing. (FH) in process engineering in
2009 and a M.S. degree in chemical engineering in 2011 at the University
of Applied Sciences in Mannheim. He is employed at the Institute of
Process Control and Innovative Energy Conversion, where he is working in
the area of spectroscopy and back scattering. He currently is writing
his Ph.D. thesis on beer haze at the Technical University of Berlin.
