Effects of deuterium oxide on formation of volatiles in linoleic acid model systems at different temperatures and oxygen limitation conditions

Effects of 30, 60, and 90°C treatments and oxygen limitation on formation of volatiles were determined for linoleic acid model systems containing deuterium oxide (D₂O) and deuterium free water. The presence of D₂O accelerated consumption of headspace oxygen, indicating that the rate of lipid oxidation increased in the presence of D₂O. The presence of deuterium in headspace volatiles was indirectly determined based on comparison of the amount of the fragmented mass to charge ratio (m/z) (molecular weight, Mw), which was 73.1/72.1 for d₁-pentane/pentane and 125.1/124.1 for d₁-2,4 octadienal/2,4 octadienal. The ratio of 73.1/72.1 (m/z) for pentane was significantly (p<0.05) higher for samples containing D₂O than for samples containing deuterium free water at 30, 60, and 90°C. Other volatiles did not follow the same pattern. 2,4-Octadienal in samples under unlimited oxygen conditions confirmed this trend, indicating that water was incorporated into volatiles during oxidation of linoleic acid under these conditions.