Comparison of the volatiles formed by oxidation of phosphatidylcholine to triglyceride in model systems.

The oxidative stability of oleoyl and linoleoyl residues esterified in the form of triglyceride (TAG) and phosphatidylcholine (PC) during thermal treatment was investigated. Headspace solid-phase microextraction (HS-SPME) followed by gas chromatography-mass spectrometry (GC-MS) analysis was used to determine the volatile compounds from oxidized PL and TAG molecular species. The results showed that aldehydes were the major volatile oxidized compounds (VOCs) of 1-stearoyl-2-oleoyl-sn-glycero-3-phosphocholine (SOPC), 1-stearoyl-2-linoleoyl-sn-glycero-3-phosphocholine (SLPC), and 1,3-distearoyl-2-linoleoyl-glycerol (SLS), while ketones, especially saturated methyl ketones, were the major VOCs of 1,3-distearoyl-2-oleoyl-glycerol (SOS). The monitoring of the oxidative degradation using liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) showed that either monounsaturated or diunsaturated fatty acyl groups were less oxidized when in the form of PCs than when in the form of TAGs. This finding demonstrated that the choline group in the form of PCs could increase the stability of fatty acyl groups to oxidation in comparison to TAGs.