Open Access
Effects of ozonation on the physicochemical properties and antimicrobial activity of virgin and pomace olive oils
(Wiley, 2025-05-22) Domínguez-Lacueva, Paula; Corella Guillamón, Paula; Cantalejo Díez, María Jesús; Agronomía, Biotecnología y Alimentación; Agronomia, Bioteknologia eta Elikadura; Institute on Innovation and Sustainable Development in Food Chain - ISFOOD; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa; Gobierno de Navarra / Nafarroako Gobernua
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.
Open Access
Excitation-emission matrix spectroscopy coupled with chemometrics for monitoring ozonation of olive oil and olive pomace oil
(Royal Society of Chemistry, 2025-02-07) Domínguez-Lacueva, Paula; Sikorska, Ewa; Cantalejo Díez, María Jesús; Institute on Innovation and Sustainable Development in Food Chain - ISFOOD
The effects of ozonation on the Total Polyphenol Content (TPC) of olive oils remain largely unexplored, despite the significant role that polyphenols play in enhancing the health benefits and quality of these oils. Understanding how ozone treatment impacts phenolic compounds is vital, especially considering the documented negative effects of thermal and photochemical oxidation on TPC. The aim of this study was to explore the use of fluorescence spectroscopy combined with chemometrics to develop multivariate models for monitoring the effects of ozonation on TPC and key physicochemical parameters such as the peroxide index (PI), acidity index (AI), iodine value (IV) and viscosity (V) in both, virgin and pomace olive oils. Parallel factor analysis and principal component analysis of fluorescence excitation¿emission matrices (EEMs) of ozonated olive oils revealed that as the ozonation process progressed, TPC and fluorescence emission decreased. And, at the same time, ozonation increased the values of oxidation indicators such as PI, AI, viscosity and intensity of the Rayleigh scattering signal. PLS models based on analysis of unfolded EEMs exhibited good predictive performance for PI (R2 = 0.822; RPD > 2.5), and moderate for TPC and V (R2 = 0.792 and 0.753; RPD > 2). In summary, we demonstrated the feasibility of EEM spectroscopy for monitoring the ozonation process. The use of this method can ease the characterization of ozonated olive oils and, additionally, make the analysis more sustainable.
Open Access
Changes in the quality parameters and antimicrobial activity of ozonated virgin and pomace olive oils under different storage conditions
(MDPI, 2025-03-15) Domínguez-Lacueva, Paula; Corella Guillamón, Paula; Cantalejo Díez, María Jesús; Institute on Innovation and Sustainable Development in Food Chain - ISFOOD
Ozonated olive oils have emerged as a promising alternative for natural antimicrobial agents in the food industry due to their potential to inhibit microbial growth. However, the stability and effectiveness of these oils under different storage conditions has not been thoroughly explored. This study examines the changes in the physicochemical properties and antimicrobial activity of ozonated virgin olive oil (VOO) and pomace olive oil (POO), stored at 4 ◦C and 20 ◦C for 6 months. The peroxide index (PI), acidity index (AI), iodine value (IV), and viscosity (V) were analyzed, along with their antimicrobial activity against Escherichia coli (STCC 45), Pseudomonas aeruginosa (STCC109), and Staphylococcus aureus (STCC 239). The results showed that both oils underwent changes in their physicochemical properties and antimicrobial activity over time. The PI initially increased up to day 30, with VOO reaching a peak value of 741.44 ± 32.16 meq O2/kg and POO reaching 1067.23 ± 56.56 meq O2/kg, but after this point, it began to decrease in both oils and at both temperatures (4 ◦C and 20 ◦C). The acidity index (AI) increased over time, particularly in POO, which reached a final value of 6.32 ± 0.14 mg KOH/g. Both oils showed a reduction in iodine value (IV), and an increase in viscosity (V) over time. In terms of antimicrobial activity, P. aeruginosa remained stable with an average inhibition zone of 9.41 ± 0.23 mm, while E. coli showed the greatest increase in activity over time, reaching 21.31 ± 4.01 mm in POO at 20 ◦C. On the other hand, S. aureus exhibited the highest average antimicrobial activity, with a mean inhibition diameter of 14.49 ± 0.36 mm, and the largest inhibition zone of Ø = 18.97 ± 1.46 mm observed after 180 days of storage. A Spearman correlation analysis revealed a strong positive relationship (ρ > 0.85, p < 0.05) among PI, AI, and the antimicrobial activity with storage duration. This study provides novel insights into the stability of ozonated oils, offering valuable perspectives for their application in the food industry, especially using pomace olive oil, a key by-product in olive oil production.

Cantalejo Díez, María Jesús

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