Flavor reversion in soybean oil. V. Isolation and identification of reversion compounds in hydrogenated soybean oil

Summary A reinvestigation of the deodorization condensates obtained from reverted, hydrogenated soybean oil has been made. The flavor materials were further concentrated by vacuum distillation at room temperature and by separation into neutral and acid fractions. Qualitative tests indicated that the flavor components were mainly α,β‐unsaturated carbonyls. Hydrogenation of the fractions possessing flavors destroyed the α,β‐unsaturated carbonyls as well as the flavors. Oxidation of the carbonyls to the corresponding acids gave similar results. Three compounds were isolated as the 2,4‐dinitrophenylhydrazones. They were identified as maleic dialdehyde, di‐n‐propyl ketone, and 2‐heptenal by the use of physical as well as chemical data. A possible mechanism for the formation of two of these compounds from fatty acid precursors has been indicated.