ANDREA E. FALTERMAIER (1), Thomas Becker (2), Elke K. Arendt (1), Martina Gastl (2)
(1) School of Food and Nutritional Sciences, National University of
Ireland, University College Cork, Cork, Ireland; (2) Technische
Universität München-Weihenstephan, Lehrstuhl für Brau- und
Getränketechnologie, Freising, Germany
During the malting process, high molecular weight storage proteins
are degraded by proteolytic enzymes to both mid-size and small peptides
as well as to amino acids. Until now, only a little knowledge has
existed about the chemical pathways and the factors that influence those
degradation reactions during malting. In this paper, a fundamental
study on protein changes taking place during the malting of common wheat
(Triticum aestivum L.) is presented. Changes in content and
composition of molecular fractions were investigated during the
steeping, germination, and kilning process. Pilot-scale malting trials
with a standard malting regime (7 days of germination at 15°C with a
steeping degree of 45%) were done in order to ensure a comparable malt
modification at the end. Samples taken of every single malting step and
additionally daily during germination were analyzed to get a deeper
insight into proteolytic breakdown which takes place during the malting
process. Variations in protein content and composition in relationship
to the degree of modification are shown. The malt was analyzed according
to ASBC and EBC methods. Protein fractions were analyzed using a
lab-on-a-chip technique, which separates the proteins—based on their
molecular weight—by capillary electrophoresis, and was supported by
using two-dimensional gel electrophoresis. In addition, the impact of
malting on the ultrastructure of wheat was evaluated using scanning
electron microscopy (SEM) and confocal laser scanning microscopy (CLSM).
Using those techniques, it is possible to visualize the changes in
structure and thereby to get a deeper insight into the kernel itself.
All results were compared to the changes taking place during the malting
of barley. By interpretation of those results, possibilities for the
optimization of final beer quality depending on the degree of
modification of the used malt can be shown.
Andrea Faltermaier studied food technology at the Technische
Universität München (TUM), Weihenstephan, Germany. She performed her
diploma thesis work at the Lehrstuhl für Brau- und Getränketechnologie,
TUM-Weihenstephan. Since 2009 Andrea has been a Ph.D. student at the
University College Cork (UCC), and she received the InBev-Baillet Latour
Scholarship in Brewing and Malting. Her Ph.D. project, a cooperation
between UCC and TUM, deals with studies on the application of wheat in
brewing and functional beverages.
