A study on the impact of industrial-scale refining on olive oil and olive pomace oil contamination with mineral oils

Mineral oil hydrocarbons (MOH), including saturated (MOSH) and aromatic (MOAH) hydrocarbons, are contaminants of petrogenic origin. On-line high-performance liquid chromatography (HPLC) - gas chromatography (GC) - flame ionization detector (FID) was used for determining MOH in olive oils (OOs) and olive pomace oils (OPOs) at different stages of the refining process and in samples from the Italian market. Deodorization reduced contamination by about 30 %, resulting in a significant reduction of endogenous n-alkanes generally up to n-C31. Comprehensive GC coupled to quadrupole time-of-flight (QTOF) mass spectrometry (MS) allowed investigating the effect of bleaching on a sample of OPO naturally contaminated with alkylated PAHs, demonstrating the removal capacity of this refining step on potentially carcinogenic genotoxic compounds derived from MOH contamination. OOs from the market contained on average 33.1 mg/kg of MOSH n-C10-50 and 3.3 mg/kg of MOAH, while OPOs contained on average 160.7 and 36.1 mg/kg of MOSH and MOAH, respectively.