Georg Krebs (1), Thomas Becker (1)
Martina Gastl (2); (1) Chair of Brewing and Beverage Technology, Technische Universität München, Freising, Germany
Technical Session 13: Sensory II
Tuesday, August 16 • 8:15–9:30 a.m.
Plaza Building, Concourse Level, Governor’s Square 15
Beer is a complex mixture of various polymers differing in their substance class. Numerous polymeric grain ingredients like polysaccharides and proteins are degraded into lower molecular weight substances during the malting and mashing process. Polymers affect the sensory perception of beverages in terms of palate-fullness and mouthfeel. An adequate fullness and harmony are essential for cereal-based beverages. Asymmetric flow-field-flow fractionation (FFF/AF4) coupled with multi-angle-light-scattering detection (MALS) is applied for the characterization of polymers in single-substance solutions. However, in complex multicomponent solutions like beverages different substance classes could not be distinguished even when detectors with different sensitivities (refractive-index detection, UV absorption) were used. The objective of this study was to develop a method for identifying different substance classes in an AF4-MALS-UV-dRI chromatogram of a polymer mixture in beer. In order to achieve this, we systematically removed specific substance classes and compared the elution profile of beer with chromatograms of standard solutions. The AF4-fractogramm of beer was classified into three main substance classes: proteins elute in the low molecular weight fraction, protein-phenol complexes elute in the medium molecular weight fraction and cell-wall polysaccharides were identified in the high molecular weight fraction. The differences in the hydrolytic processes of malts with varied malting regime were detected by the developed method. A correlation of palate-fullness and molecular weight of the polymers was shown and confirmed. Thus, it was shown that the palate-fullness of the beverage can be influenced by malt modification, which can be verified by the developed method.
Georg Krebs studied brewing and beverage technology at the Technische Universität München in Weihenstephan. He received his diploma degree in 2013 on the topic “Influence of Different Maltodextrins at the Palate Fullness of Nonalcoholic- and Raw Grain Beer.” Since 2013 he has worked as a Ph.D. student at the Chair of Brewing and Beverage Technology (head of chair: Prof. Thomas Becker). The research is on the Fractionation of Starch from Different Sources.”