Facts and 'artefacts' in the flavour chemistry of onions

Sulfur compounds play an important role in the flavour of onions. However, due to the degradation of precursors and the occurrence of transient, unstable flavour compounds it is quite difficult to define a specific type of onion odour, because a tremendous number of reactions may occur depending on the processing parameters applied. The importance of the use of appropriate analytical methods will be emphasised with respect to artefact formation, e.g. excessive generation of volatiles from precursors during the work-up procedure. The exact structure elucidation for 3,5-diethyl-1,2,4-trithiolane is shown.