Non-thermal plasma effects on the lipoxygenase enzyme activity, aroma and phenolic profiles of olive oil

Effects of non-thermal plasma (NTP) technology on the aroma and phenolic compositions and inactivation of lipoxygenase (LOX) enzyme activity of extra virgin olive oil were investigated for the first time. A short non thermal plasma treatment with pure argon gas (2 standard liters per minute and an average voltage of 7 kV) was applied for 135 s on the olive oil sample. The LOX activity in the NTP treated oil was inhibited up to 42.9% in comparison with untreated oil. Mean values of the peroxides in both samples, expressed in meq oxygen/kg of oil, did not show any statistically significant difference. The values of the antioxidant potentials in the samples proved a mild reduction after NTP treatment. A total of 14 phenols and 31 volatiles were found in both samples with same profile. Although there was a slight difference in the test samples with regard to the concentration of individual phenolic and aroma compounds, this difference was not statistically significant. Therefore, NTP treatment had no statistically significant influence on the antioxidant activity, peroxide value, phenols and volatiles, except LOX activity.