Schubert, C.1, Thoerner, S.1 and Rettberg, N.1, (1)VLB Berlin, Berlin, GERMANY
Poster
Beer contains numerous short- and medium-chain monocarboxylic acids. These are either released during fermentation, yeast autolysis, or they originate from raw materials. Raw material-derived monocarboxylic acids are primarily associated with hop bitter acid synthesis and degradation. Their particular role in dry-hopped beer has been discussed recently, surely they contribute to the complex flavor of these products. In brief, short- and medium-chain acids contribute to beer flavor and quality due to two primary reasons: first, fatty acids themselves are aroma active; second, they act as key precursors for flavor-active ethyl esters (e.g., ethyl hexanote or ethyl butyrate) in beer. Both aspects imply the (increasing) demand for suitable tools for their instrumental analysis. Short- and medium-chain acids are usually analyzed by GC, whereas different methods of sample preparation and detection have been published. Generally, the assays for food and beverage analysis differ strongly with respect to manual handling, use of toxic solvents, degree of automation, and method performance (analyte spectrum, working range, etc.). In order to meet the demands of practical brewers, the current paper describes the development and application of an HS-SPME-FID method for beer profiling toward aroma-active short- and medium-chain monocarboxylic acids. Analysis results for commercial beers and process intermediates are presented to establish an understanding of variables that fundamentally influence acid concentrations in beer.
Nils Rettberg (born 1983) is a trained brewer and maltster, holding a diploma in biotechnology with a focus on brewing science from TU Berlin (Germany). Initiated by his diploma thesis on “Flavor Active Epoxydecenals from Lipid Oxidation” he developed a deep interest in the analysis of molecules that make beer taste either terribly good or horribly stale. From 2011 to 2014 Nils performed his doctoral thesis on “Comprehensive Analysis of Hop Secondary Metabolites.” Simultaneously, he was a research associate at TU Berlin (Chair of Bioanalytics) and VLB Berlin (Research Institute for Special Analyses), where he was involved in both research and teaching. In January 2015 Nils became head of the VLB Research Institute for Special Analysis. Since October 2015 Nils has been in charge of the VLB Research Institute for Instrumental Beer and Beverage Analysis.
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