Unsaturated aliphatic aldehydes are microcomponents of a great many plants and animal products. They are believed to be secondary products originated from fatty acids. (E,E)-2,4-Nonadienal is one of a few unsaturated C9-aldehydes which are produced industrially. The physicochemical and spectral data of the aldehyde are given in Table I.
The compound has a fatty, waxy odor and is applied both in flavors and in fragrances. Its biogenesis, as with (E,Z)-2,6-nonadienal, can be rationalized by invoking a reasonably small number of metabolic pathways in which nonvolatile polyunsaturated fatty acids serve as the most important precursors in biogeneration of aromas.
(E,E)-2,4-Nonadienal is also a product of oxidative degradation of methyl and ethyl esters of linoleic acid. Although this aldehyde occurs in several plants and animal products, there are no known rich natural sources of this flavor compound.