Decadienal/decatrienal

Detailed investigation of T. rotula and other diatom species revealed that 2,4-decadienal (24) and 2,4,7-decatrienal (27) represent only members of a structurally diverse class of oc, 3,y,6-unsaturated aldehydes found in several... 

Flavors and aromas commonly associated with seafoods have been intensively investigated in the past forty years ( l-7), but the chemical basis of these flavors has proven elusive and difficult to establish. Oxidized fish oils can be described as painty, rancid or cod-liver-oil like (j ), and certain volatile carbonyls arising from the autoxidation of polyunsaturated fatty acids have emerged as the principal contributors to this type of fish-like aroma ( 3, 5, 9-10). Since oxidized butterfat (9, 11-12) and oxidized soybean and linseed oils (13) also can develop similar painty, fish-like aromas, confusion has arisen over the compounds and processes that lead to fish-like aromas. Some have believed that the aromas of fish simply result from the random autoxidation of the polyunsaturated fatty acids of fish lipids (14-17). This view has often been retained because no single compound appears to exhibit an unmistakable fish aroma. Still, evidence has been developed which indicates that a relatively complex mixture of autoxidatively-derived volatiles, including the 2,4-heptadienals, the 2,4-decadienals, and the 2,4,7-decatrienals together elicit unmistakable, oxidized fish-oil aromas (3, 9, 18). Additionally, reports also suggest that contributions from (Z -4-heptenal may add characteristic notes to the cold-store flavor of certain fish, especially cod (4-5). 

The purely thermal processes that are involved include the formation of cw-9,10-dihydronaphthalene (C9,10) from bullvalene (BV), bicyclo[4.2.2]decatetrene (422) and its intramolecular Diels-Alder adduct, tetracyclo[4.4.0.0 0 ]decadiene (TCD), from lumibullvalene (LBV), isobullvalene (IBV), tricyclo[5.3.0.0 ]deca-3,5,9-triene (TDT), and isolumibullvalene (ILBV), from basketene (BSK), NHC, TRQ, and the syn and anti isomers of tricyclo[4.4.0.0 ]decatriene (S and A, respectively), and from all c/ -cyclodecapentaene (C5), snoutene (SNT), and diademane (DIA). A more recent review includes many heats of formation and enthalpies of activation ... 

The main volatile compounds detected from autoxidized trilinolein monohydroperoxides include pentane, hexanal, 2-heptenal and 2,4-decadienal. The volatiles from trilinolenin and monohydroperoxides include propanal, 2,4-heptadienal and 2,4,7-decatrienal. Mixtures of 1 1 trilinolein and trilinolenin autoxidized at low peroxide values (PV 34) show equal contribution of volatiles derived from linoleate and linolenate hydroperoxides. 

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