Effects of ozonation on the physicochemical properties and antimicrobial activity of virgin and pomace olive oils

Ozonated olive oils are recognized for their remarkable antimicrobial properties. The reaction between ozone (O3) and unsaturated fatty acids leads to the formation of bactericidal compounds (ozonides, aldehydes, and peroxides) with valuable applications. This study represents the first comprehensive investigation into the effects of a wide range of ozone exposure durations (from 0 to 48 h) on the physicochemical properties and antimicrobial activity of both virgin olive oil (VOO) and pomace olive oil (POO), along with a thorough statistical analysis of the correlation between ozone dose and these parameters. The physicochemical indicators, including fatty acid methyl ester (FAME) composition, peroxide index, acidity index, iodine value, and viscosity, were measured at ozonation doses ranging from 0 to 1 mol O3. Significant changes were observed with increasing ozonation time, including a 69% and 46% reduction in oleic acid content, as well as increased peroxide values of 1255.2 mEq O₂/kg and 1878.8 mEq O₂/kg for VOO and POO, respectively. Antimicrobial activity was evaluated against Escherichia coli (STCC 45), Pseudomonas aeruginosa (STCC 109), and Staphylococcus aureus (STCC 239), with the highest inhibition observed against S. aureus (22.68 mm with POO at 48 h and 1 mol O3). PCA analysis identified three groups: low ozone doses (0–0.08 mol O₃) associated with higher iodine values; intermediate doses (0.16–0.5 mol O₃) linked to increased peroxide, acidity, viscosity, and antimicrobial activity; while high doses (1 mol O₃) provided no further benefits, suggesting that moderate doses are sufficient for effective antimicrobial activity. These findings highlight the potential of ozonated olive oils for novel applications in the food industry.