posted on 2019-12-20, 17:54authored byClemens Kanzler, Paul T. Haase
Thermal treatment of food leads to the formation of melanoidins
by reactions of carbohydrates with free amino acids or proteins in
the late stage of Maillard reaction. The aim of this study was the
identification of reaction mechanisms responsible for the formation
of melanoidins involving active methylenes with the heterocyclic structure
and the structural characterization of the resulting products. For
this purpose, norfuraneol was incubated with the aldehydes pyrrole-2-aldehyde
or furfural at 125 °C. With the help of high-resolution mass
spectrometry, the structural composition of oligomers of up to fifteen
C5-units could be described for the first time. Aldol and
Michael reactions could be identified as crucial steps for the formation
of new C–C-bonds. With increasing heating time, the elimination
of water from the products was facilitated, and oxidation reactions
of integrated reductone structures lead to the expansion of conjugated
double-bond systems responsible for the color formation of the samples.