Cinetica di variazione del potere antiossidante dell’olio extra vergine di oliva in fase di stoccaggio

The degradation kinetics of antioxidant activity, free acidity, peroxide value, and spectroscopic indices in the UV region of monovarietal extra virgin olive oils (cv. Taggiasca) were studied during 8 months of storage in closed bottles, in the dark, at 25-40°C. Results showed that the secoiridoids and α-tocopherol decreased following pseudo-first order kinetics, and the dialdehydic form of decarboxymethyl oleuropein aglycone was the most unstable. The antioxidant activity, as evaluated in vitro by using the 2,2-diphenyl-1-picrylhydrazyl radical, decreased following a pseudo-first order kinetic. Free acidity, peroxide value, and the spectroscopic indices in the UV region increased following pseudo-zero order kinetics, and K232 was the first parameter that exceeded the upper established limit for extra virgin olive oil. A time-temperature plot was used to represent the behaviour of all quality indices during storage. This plot reveals the operating conditions in which the quality of product may be maintained.