Online monitoring of olive oils headspace by proton transfer reaction-mass spectrometry

In this work we evaluated the possibility to use the proton transfer reaction mass spectrometry (PTR-MS) for the online monitoring and direct sampling of olive oil headspace. In a first experiment, the headspace of an extravirgin olive oil at 33 c was continuously monitored for more than 70 hours observing the formation of compounds related to secondary oxidation products, showing that it is possible to monitor with high temporal resolution and without sample preparation the oxidation process of the oil. in a second experiment, extravirgin olive oils were subjected to an accelerated thermo-oxidation process. during that experiment, peroxide value was monitored by means of a spectrophotometric method, and the head space was monitored by PTR-MS. Increasing of peroxide value during the thermo-oxidation was highly correlated with several volatile compounds originating from oxidation processes and in particular with aldehydes arising from lipid hydroperoxides.