Amino acid-catalyzed conversion of citral: cis-trans isomerization and itsconversion into 6-methyl-5-hepten-2-one and acetaldehyde

Under alkaline conditions, amino acids or proteins catalyze the deacetylati on of citral, a major aroma component, resulting in methylheptenone and ace taldehyde formation. 3-Hydroxycitronellal is an intermediate in this reacti on. Amino acids also catalyze the cis-trans isomerization of the pure isome rs of citral, geranial, and neral. Most likely the amino acids are involved in stabilizing intermediates of the isomerization and deacetylation reacti on of citral. On the basis of the findings presented, some consequences for the application of citral, or its isomers, in food are discussed.