Characterization of (Z)- and (E)-(4,5)-epoxy-2E-decenals by isotope dilution assays (IDA)

摘要

Z- and .E-4,5-epoxy-2E-decenals are strongly reactive and off-flavour compounds resulting from the peroxidation of fatty acids. A novel and simple chemical synthesis of deuterium and C-13 labelled Z- and E-4,5-epoxy-2E-decenals was established. Deuterated epoxydecenals were used in isotope dilution assays for quantification and C-13 labelling was used to characterise reaction products of C-13 epoxydecenals with compounds in beer or wort by C-13 NMR. The flavour of Z-epoxy-2E-decenal was confirmed to be metallic, whilst the trans-epoxide was classified as malt-like. Epoxydecenals were analysed successfully in malt, wort, beer and cereals. The beer flavour is of high relevance for the practical brewer and until now low attention was given to the epoxydecenals.