Weronika Filipowska
KU Leuven

FLAVOUR STABILITY
Keywords: malting, staling aldehydes

Beer off- flavours are associated with the presence of carbonyl compounds, which may appear in aged beer by de novo formation or by release from bound-state. Malt, as a major raw material for the beer production delivers precursors for aldehyde formation but also provides these compounds itself.

Beer staling aldehydes were monitored during the entire process of malting – from barley to pale lager malt. The main aim of the research, was to investigate which step of malting process is the most critical for the formation of aldehydes. The HS-SPME-GC-MS method was developed and applied.

The results showed that the drying process was the most critical – oxygen-boost and heat load had a significant impact on the formation of oxidized fatty acids and degradation of amino acids. This resulted in the formation of aldehydes derived from Strecker degradation (2-methylpropanal, 2-methylbutanal, 3-methylbutanal, methional, phenylacetaldehyde), Millard reaction (furfural) and fatty acids oxidation (hexanal and t-2-nonenal). It could be suggested that the malting technology has a great influence on beer flavour stability. The results indicate the critical processing steps during malting, with regard to aldehyde evolution.”