Coulometrically determined antioxidant capacity (CDAC) as a possible parameter to categorize extra virgin olive oil

Abstract

Antioxidant capacity of extra virgin olive oil (EVOO) is associated with the overall content of health-promoting compounds, including biophenols. In this work, antioxidant capacity of polar extracts from 42 EVOO and 3 edible seed oil samples was evaluated by constant-current coulometry, using Br₂ electrogenerated at a Pt anode as the titrant and bioamperometric detection of the end-point through Br₂ excess. The Coulometrically Determined Antioxidant Capacity (CDAC) of EVOO extracts covered the 8-25 mmol electrons (e^-) kg^-1 range, while it was lower for seeds oils (≤5 mmol e^- kg^-1). Average CDAC of EVOO with biophenols ≥ 250 mg kg^-1 (15 ± 4 mmol e^- kg^-1) was significantly higher than EVOO with biophenols < 250 mg kg^-1 (10 ± 2 mmol e^- kg^-1). CDAC is a robust, cheap, and rapid test that could be exploited to classify EVOO relying on antioxidant capacity rather than on HPLC-determined content of biophenols.

Keywords: Antioxidants; Biamperometry; Biophenols; Constant-current coulometry; Coulometrically Determined Antioxidant Capacity (CDAC); Extra virgin olive oil.