Distribution of volatile sulfur compounds in an interspecific hybrid between onion (Allium cepa L) and leek (Allium porrum L)

Volatile sulfur compounds of an interspecific hybrid between Allium cepa and Allium porrum were analyzed by gas chromatography (GC) and GC/mass spectrometry prior to isolation of the individual oils by a simultaneous distillation/extraxtion (SDE) method. Furthermore, the aroma profiles of various onion and leek cultivars were investigated. Major volatile components detected in onion were 2-methyl-2-pentenal, (E)-methyl 1-propenyl disulfide, methyl propyl trisulfide, and propanethiol, whereas dipropyl trisulfide, dipropyl disulfide, and (E)-propenyl propyl disulfide predominated in leek oils. According to the higher amount of leek chromosomes in the cell nucleus, the percentages of the measured sulfur volatiles in the hybrid material correspond more to the leek than to the onion flavor profile. Discrimination analysis was successfully applied to classify the three predefined Allium groups. It has been found that at minimum five of the most important aroma volatiles were necessary to receive sufficient differentiated clusters without any overlapping areas. This graphical display demonstrates very clearly the influence of the genetic background of the parent varieties on the sulfur volatile composition in the Allium hybrid.