An electrochemical index approach to assess the antioxidant capacity of olive oils extracts using a Sonogel-Carbon electrode

This study proposes a rapid and cost-effective electrochemical method for evaluating the antioxidant capacity of olive oil extracts by using differential pulse voltammetry. Fourteen commercial oils, including extra virgin olive oils (EVOO), a virgin olive oil (VOO), olive oils, olive pomace oils, and a sunflower oil, were analysed. The extraction of polyphenolic compounds from the oils was performed following the official International Olive Council method. The antioxidant capacity was assessed using the ABTS and DPPH spectrophotometric methods. Electrochemical measurements results showed EVOO and VOO with higher electrochemical index than the rest (≥2), with repeatability lower than 5%, strongly correlating with ABTS (% inhibition, R 2 = 0.9662) and DPPH (R 2 = 0.9319) results. No electrochemical response was observed in OPO and SO extracts. The first anodic peak (I 1 /E 1 ) correlated more closely with antioxidant activity, suggesting it reflects the contribution of polyphenols bearing ortho-dihydroxyl groups. Consequently, I 1 /E 1 , can be considered as a reliable indicator of antioxidant capacity in olive oils.