Influence of packaging type and storage temperature on the shelf life of soft and mild veiled olive oils: A kinetic and thermodynamic evaluation

Shelf-life of veiled (unfiltered) extra virgin olive oil (EVOO) remains insufficiently characterized under different packaging systems and storage temperatures. This study evaluated changes in free acidity (FA), peroxide value (PV), and specific UV extinction coefficients (K 232 and K 268 ) in two veiled EVOOs. These oils, classified as soft and mild, differed in initial water content (0.12 vs. 0.16% w/w), insoluble solid content (0.11 vs. 0.22% w/w), phenolic content (119 vs. 265 mg GAE kg⁻¹) and green fruitiness intensity (1.5 vs. 5.5). Samples were stored in darkness for 12–21 months at 10–40 ºC, using dark glass bottles or multilayer flexible pouches. All quality parameters increased significantly during storage, although the influence of temperature was not always clear. Oils kept in glass bottles exhibited significantly higher primary oxidation levels than those stored in pouches, as reflected by PV (14.0 vs. 9.5 meq O 2 kg⁻¹) and K 232 (2.40 vs. 2.04). Zero-, first-, and second-order kinetic models described quality changes (0.863 < R < 0.999), except for FA in mild oils stored in glass at 10 ºC. Arrhenius dependence was observed for FA and K 268 rate constants. Thermodynamic transition-state theory showed that veiled oil oxidation was non-spontaneous (positive Gibbs free energy), endergonic (negative activation entropy), and endothermic (positive activation enthalpy). Predicted shelf-life values agreed with experimental findings, being 8–18 months in pouches and 4–15 months in glass, decreasing at higher temperatures and from soft to mild oils. Pouches allowed extending EVOO shelf life, representing a promising alternative to conventional glass packaging.