Effect of an olive phenolic extract on the quality of vegetable oils during frying

The potential of a phenolic extract (PE) from olive vegetation water (OVW) to limit the negative effects of frying was tested after adding it at different concentrations to a refined olive oil (RO). Its efficacy was also compared to ROs containing butylated hydroxytoluene (BHT) and an extra virgin olive oil (EVOO) with a high polyphenol content. Analyses of the oils collected after 30 min, 1, 2, 4, 6, 8, 10 and 12 h of frying at 180 °C, demonstrated that degradation of the polyphenols was proportional to the original content; at a concentration of at least 400 mg/kg of polyphenols, PE was able to reduce oxidation of the tocopherols and the emission of low-molecular-weight aldehydes better than BHT and with similar results to the EVOO. In addition, secoiridoid oxidative compounds were examined by high-performance liquid chromatography/triple quadrupole tandem mass spectrometry with electrospray ionisation.