COMPARISON OF ONION VARIETIES BY HEADSPACE GAS-CHROMATOGRAPHY MASS-SPECTROMETRY

Volatile aroma compounds of crushed onions (Allium cepa L.) were analyzed over a 6-month storage period after harvesting. Compositions of the headspace of five varieties, Jumbo, Robusta, Sturon, Hygro, and Lafort, were analyzed by a static sampling procedure using gas chromatography (GC) and GC-mass spectrometry. Most prominent among the 27 identified aroma compounds were dipropyl disulfide, methyl propyl disulfide, 1-propenyl propyl disulfides (E and Z), methyl 1-propenyl disulfides (E and Z), 1-propanethiol, dipropyl trisulfide, methyl propyl trisulfide, 2-methyl-2-pentenal, two compounds tentatively identified as 3-ethyl-l,2-dithi-5-ene and 3-ethyl-l,2-dithi-4-ene, and finally S-propyl thioacetate. Most prominently differing from each other were the varieties Jumbo and Lafort, whereas Hygro and Lafort were more closely related. The distribution pattern of the major compounds varied little during storage. © 1990, American Chemical Society. All rights reserved.