title: Quantification of key odorants formed by autoxidation of arachidonic acid using isotope dilution assay.
abstract: Six odor-active compounds generated by autoxidation of arachidonic acid (AA) were quantified by isotope dilution assay (IDA), i.e., hexanal (1), 1-octen-3-one (2), (E,Z)-2,4-decadienal (3), (E,E)-2,4-decadienal (4), trans-4,5-epoxy-(E)-2-decenal (5), and (E,Z,Z)-2,4,7-tridecatrienal (6). Compound 1 was the most abundant odorant with about 700 mg/100 g autoxidized AA, which corresponds to 2.2 mol% yield. Based on the odor activity values (ratio of concentration to odor threshold), odorants 3 (fatty) and 5 (metallic) showed the highest sensory contribution followed by 1 (green), 2 (mushroom-like), 6 (egg white-like), and 4 (fatty). For the first time, reliable quantitative results are reported for odorants 1-6 in autoxidized AA, in particular odorant 6, which is a characteristic compound found in autoxidized AA. Synthesis of deuterated 6, required for IDA, is described in detail. The formation of odorants 1-6 by autoxidation of AA is discussed with respect to the quantitative data.
authors.affiliation: Nestec Ltd., Nestlé Research Center, Lausanne, Switzerland.
authors.forename: J
authors.initials: J
authors.lastname: Lin
authors.forename: L B
authors.initials: LB
authors.lastname: Fay
authors.forename: D H
authors.initials: DH
authors.lastname: Welti
authors.forename: I
authors.initials: I
authors.lastname: Blank
mesh_terms: D000447:Aldehydes / Q000032:analysis; D016718:Arachidonic Acid / Q000737:chemistry*; D002247:Carbon Isotopes; D002849:Chromatography, Gas; D003903:Deuterium; D004852:Epoxy Compounds / Q000032:analysis; D007201:Indicator Dilution Techniques; D007553:Isotope Labeling; D007554:Isotopes; D007659:Ketones / Q000032:analysis; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D009812:Odorants / Q000032:analysis*; D010084:Oxidation-Reduction; D013237:Stereoisomerism
chemical_list: C096140:4,5-epoxy-2-decenal; D000447:Aldehydes; D002247:Carbon Isotopes; D004852:Epoxy Compounds; D007554:Isotopes; D007659:Ketones; C057349:2,4-decadienal; D016718:Arachidonic Acid; C113805:1-octen-3-one; C010463:n-hexanal; D003903:Deuterium