Maciej Ditrych
KU Leuven

STABILNOŚĆ SENSORYCZNA
Słowa kluczowe: brewing, staling aldehydes

Flavour characteristics of beer are the critical aspects under which beer is evaluated. Many of the off-flavours are related to the presence of the so-called staling aldehydes. The formation mechanisms of these compounds are yet not fully understood. With regard to beer, aldehydes may arise from e.g. fatty acid oxidation, Maillard reactions or from Strecker degradation of amino acids.

However, aldehydes can be released from the precursor forms, the so-called “bound-state aldehydes”. Therefore, to unravel anther puzzle piece of the chemistry lying behind the aldehyde formation and/or release we have monitored the entire brewing process with regard to these compounds. The wort was produced in our 5 [hl] pilot brewing plant in oxygen free conditions. The samples were collected during: onset of mashing, end of mashing, mash filtration-first wort, onset of boiling, end of boiling, end of clarification and end of cooling (before wort aeration). The concentrations of 2-methylpropanal, 2-methylbutanal, 3-methylbutanal, hexanal, furfural, phenylacetaldehyde and E-2-nonenal were determined by HS-SPME-GC-MS.

The content of all the aldehydes decreased remarkably over the entire brewing process, with the exception of furfural, which increased over the boiling and hot trub separation. Highest aldehyde reduction (except furfural) was observed during boiling process. The study indicate that a considerable amount of aldehydes originates from raw materials (malt), of which some can be reduced over the brewing process.