Identification of Intermediates in the Formation of Onion Flavor

Abstract
Headspace gas and ether extract of sliced or homogenized onion were analyzed by using GLC. Dialkyl disulfides, main components of characteristic flavor of sliced onion, were found to be very little when onion was homogenized. Addtion of NaBH4 to the homogenate resulted in a marked production of disulfides while that of cysteine did not. SH compounds as cysteine and benzyl mercaptan were added to the homogenate to determine the intermediates which produced flavor with NaBH4. The presence of propyl propanethiosulfinate, propanal and thiopropanal S-oxide was confirmed by isolation and identification of their sulfide derivatives.