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Updated: Aug 15, 2026

A Toolkit to Enable Hydrocarbon Conversion in Aqueous Environments
Published on: October 2, 2012
Enzymatic hydrogenation of trans-2-nonenal in barley
Gustav Hambraeus1, Nils Nyberg
1Carlsberg Research Center, Gamle Carlsberg Vej 10, DK-2500 Copenhagen, Denmark. gustav.hambraeus@crc.dk
Abstract:
Conversion of undesirable, taste-active compounds is crucial for using barley as a suitable raw material for beer production. Here, ALH1, a barley alkenal hydrogenase enzyme that reduced the alpha,beta-unsaturated double bond of aldehydes and ketones, was found to convert trans-2-nonenal (T2N), a major contributor to the cardboard-like flavor of aged beer. Although the physiological function of ALH1 in barley development remains elusive, it exhibited high specificity with NADPH as a cofactor in the conversion of several oxylipins-including T2N, trans-2-hexenal, traumatin, and 1-octen-3-one. ALH1 action represents a previously unknown mechanism for T2N conversion in barley. Additional experimental results resolved the genomic sequence for barley ALH1, as well as the identification of a paralog gene encoding ALH2. Interestingly, T2N was not converted by purified, recombinant ALH2. The possibility to enhance ALH1 activity in planta is discussed--not only with respect to the physiological consequences thereof--but also in relation to improved beer quality.
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