THE IDENTIFICATION OF CARBONYL COMPOUNDS IN BEER

Abstract

Carbonyl compounds were separated from bottom‐fermented lager beer by extraction with a diethylether‐pentane mixture and precipitation from the extract with 2,4‐dinitrophenylhydrazine. The diketones, diacetyl and 2,3‐pentanedione, were identified as bishydrazones by thin‐layer chromatography with benzene‐petroleum ether‐ethyl acetate (34:5:1) as solvent and Silica Gel HF254 as adsorbent. For the identification of the aldehydes, the hydrazone precipitate was treated with ozone in formic acid solution and the aldehydes were determined as their corresponding carboxylic acids by iso‐thermal gas chromatography on a NEGS column. Aldehydes were found in the following order of magnitude: acetaldehyde, isobutyraldehyde, isovaler‐ and/or opt.act.valeraldehyde (2‐methylbutyraldehyde), valeraldehyde and butyraldehyde. 1967 The Institute of Brewing & Distilling