In particular, 0.10 g of sample were added with 1 mL of 0.5 % HCl in ethanol, 0.10 mL of saturated KI solution and incubated for 5 min. Then, the resulting solution was filtered and the I3- generated following the oxidation-reduction reaction between iodide and lipidic hydroperoxides was measured at 353 nm.

A matrix calibration curve, obtained by diluting a refined olive oil (ROO) sample having a PV=11.3 meqO2/Kg with a ROO with PV=2.0 meqO2/Kg, showed a good linear response (R2 = 0.9899) obtained in the analyzed concentration range (2.0-10.0 meqO2/Kg), with variation coefficients less than 5% (n=3) and limit of detection (LOD) and quantification (LOQ) of 0.2 and 0.6 meqO2/Kg, respectively. Finally, olive oil samples were analyzed by the proposed method and a good correlation with the official iodometric titration method was obtained.

In conclusion the developed spectrophotometric procedure allowed the quantitative determination of the lipidic hydroperoxides in olive oils even at the first moments of oxidation with different advantages respect to the official method in terms of analytical performances, extraction solvent (substitution of chloroform with ethanol), ease of use, and reduction of sample amounts and solvent volumes.