Evolution of Lipid Oxidation in Syrian Olive Oil under Irradiation and Storage

Aims: The current study examines variations in Syrian olive oil (SOO) after gamma irradiation treatment and during storage.

Study Design: Four irradiation treatments (0, 1, 2 and 3 kGy) were distributed in a completely randomized design with three replicates.

Place and Duration of Study: The study was conducted during 2009/2010 growing season of Kaissy olive fruits produced at Deer Al Hajar research station, Damascus, Syria.

Methodology: Measurements of selected chemical values involving, acidity value (AV), peroxide value (PV), Thiobarbituric acid (TBA) malondialdehyde value (MDA), iodine value (IV) and saponification (specification) value (SV) and selected physical values namely refractive index (RI) and viscosity were carried out using standard methods.

Results: Results revealed that the levels of the analyzed parameters was within the limits established by codex standard for the highest quality category "extra virgin" olive oils (EVOO). Gamma irradiation statistically (P <0.01) influenced AV, PV, IV, SV and viscosity of olive oils. AV, OV and MDA increased (P <0.01), while SV deceased (P <0.01) by irradiation. The lowest dose gave highest and the highest dose gives the lowest values of AV and PV. Also storage time had a significant influence on all analyzed parameters. AV and PV increased during storage time, and a maximum increase in AV (1.01%) was observed in olive oil that was treated with lowest irradiation dose.

Conclusion: Both irradiation treatment and storage time had a significant (P <0.01) effect on most of the measured chemical and physical parameters (AV, PV, MDA value, IV, SV, RI and viscosity) of EVOO.