Electron spin resonance (microESR) to determine the peroxide value of virgin olive oil

The present study aims to find correlation models between peroxide values (PVs), as determined according to the EU official method, and electron spin resonance (ESR) spectroscopy assay data, in order to use this method as an automated and solventefficient screening tool to assess the oxidative status of virgin olive oils (VOOs). The concentration of free radicals, measured at two times of a specific ESR procedure, and PVs were utilized to create linear regression models. To test them, the PVs of 7 VOO samples (3 VOOs for internal and 4 VOOs for external validation) were determined and, on the same oils, the ESR assay was performed. The results were interpolated in two models, and the PVs predicted by ESR were compared to those obtained using the official method. The two methods showed statistical consistency (p ≤ 0.05). These preliminary findings suggest that the ESR assay is an effective and sustainable screening tool for monitoring the primary oxidative state of VOOs.