Determination of acidity and electrical characterization of olive oils via electrochemical impedance spectroscopy

A. Abdelaziz; J.D. Martínez; J. Jorge

doi:10.3989/gya.0965251.2357

Authors

A. Abdelaziz Central University of Venezuela, Faculty of Sciences, School of Physics https://orcid.org/0009-0007-8056-3581
J.D. Martínez Central University of Venezuela, Faculty of Sciences, School of Chemistry https://orcid.org/0009-0005-8793-1899
J. Jorge Central University of Venezuela, Faculty of Sciences, School of Physics https://orcid.org/0000-0002-9893-1748

DOI:

https://doi.org/10.3989/gya.0965251.2357

Keywords:

Electrical conductivity, Electrochemical impedance spectroscopy, Emulsions, Oleic acid, Olive oil acidity

Abstract

Olive oil is highly valued for its nutritional and antioxidant properties. International regulations establish acidity as a key quality parameter, differentiating high-quality oils from lower grades. The acidity measurement typically involves manual titration. This study explored Electrochemical Impedance Spectroscopy (EIS) as a rapid, non-destructive alternative for determining acidity in olive oils. Emulsions were prepared using a hydro-alcoholic solution, and the standard addition method with oleic acid was employed for calibration. Electrical conductivity was derived from impedance measurements across a frequency range of 0.4 Hz to 400 KHz. Through a non-linear fit of conductivity versus oleic acid percentage, acidities of 0.30% for extra virgin olive oil and 0.19% for refined olive oil were determined. All measurements have been carried out in triplicate and both mean value and standard deviation have been calculated. Equivalent electrical circuit accurately modeled the experimental data, revealing that adsorption effects are dominant at low frequencies.

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References

Baldo MA, Oliveri P, Fabris S, Malegori C, Daniel S. 2019. Fast determination of extra-virgin olive oil acidity by voltammetry and Partial Least Squares regression. Anal. Chim. Acta 1056, 7-15. https://doi.org/10.1016/j.aca.2018.12.050 PMid:30797462

Bounegru AV, Apetrei C. 2021. Evaluation of Olive Oil Quality with Electrochemical Sensors and Biosensors: A Review. Int. J. Mol. Sci. 22 (23),12708. https://doi.org/10.3390/ijms222312708 PMid:34884509 PMCid:PMC8657724

Caicedo J, Díaz F, Osorio A. 2020. Electrical impedance spectroscopy applied to quality control in the food industry. Cienc. Tecnol. Agropecuaria, Mosquera (Colombia) 21 (1), e951

Carbonari F, Sarnari T. 2013. Il mercato internazionale e nazionale dell olio di oliva. ISMEA, 1-13.

Cataldo A, Piuzzi E, Cannazza G, De Benedetto E. 2009. Dielectric spectroscopy of liquids through a combined approach: evaluation of the metrological performance and feasibility study on vegetable oils. IEEE Sensor J. 9 (10), 1226-1233. https://doi.org/10.1109/JSEN.2009.2029454

EC 1991 Commission Regulation (EEC) 2568/91 of July 11th 1991 on characteristics of olive oil and on the relevant methods of analysis. Official EC J. L248, 0001-0083. 159.

De Magalhães J, Simon K, Veiga E, Galvao A, Robazza W. 2024. Evaluating Adulteration of Commercial Extra Virgin Olive Oil with Canola and Sunflower Oils Through Electrochemical Impedance Spectroscopy. Food Biopr. Technol. 17, 2805-2817. https://doi.org/10.1007/s11947-023-03295-8

Grossi M, Di Lecce G, Gallina T, Riccò B. 2014. A novel electrochemical method for olive oil acidity determination. Microelectr. J. 45, 1701-1707. https://doi.org/10.1016/j.mejo.2014.07.006

Grossi M, Di Lecce G, Gallina T, Riccò B. 2014. Fast and Accurate Determination of Olive Oil Acidity by Electrochemical Impedance Spectroscopy. IEEE Sensors J. 14, 2947-2954. https://doi.org/10.1109/JSEN.2014.2321323

Grossi M, Valli E, Bendini A, Gallina T, Riccò . 2022. A Portable Battery-Operated Sensor System for Simple and Rapid Assessment of Virgin Olive Oil Quality Grade. Chemosensors 10 (3), 102. https://doi.org/10.3390/chemosensors10030102

Jorge J, Jaimes G, Oliva D, Navia JA. 2018. Espectroscopia de Impedancia en Crudos de la Cuenca Apure Barinas y la Faja Petrolífera del Orinoco en un rango de frecuencias intermedias. Rev. Fac. Ing. U.C.V. 33 (2), 49-58.

Kremer F, Schönhals A. 2003. Broadband Dielectric Spectroscopy. Kremer and Schönhals Ed. Springer pag 81. https://doi.org/10.1007/978-3-642-56120-7

Lizhi H, Toyoda K, Ihara I. 2008. Dielectric properties of edible oils and fatty acids as a function of frequency, temperature, moisture and composition. J. Food Eng. 88, 151-158. https://doi.org/10.1016/j.jfoodeng.2007.12.035

Lvovich, VF. 2012. Impedance Spectroscopy Applications to Electrochemical and Dielectric Phenomena. John Wiley & Sons, Inc. New Jersey. https://doi.org/10.1002/9781118164075 PMid:22203750

Mignani AG, Smith PR, Ciaccheri L. Cimato A, Sani G. 2003. Spectral nephelometry for making extravirgin olive oil fingerprints. Sensor Actuat. B-Chem. 90, 157-162. 162. https://doi.org/10.1016/S0925-4005(03)00101-1

Ozdemir D, Ozturk B. 2007. Near infrared spectroscopic determination of olive oil adulteration with sunflower and corn oil. J. Food Drug Anal. 15 (1), 40-47. https://doi.org/10.38212/2224-6614.2447

Reyes B, Chamorro R, Morales G, Hernández R, Farías C, Valenzuela R. 2023. Chemical composition and clinical applications of extra virgin olive oil. Rev. Chil. Nutr. 50 (3), Santiago, jun. https://doi.org/10.4067/s0717-75182023000300320

Tulipani S, Martinez M, Rotches M, Estruch R, Escribano E, Lacueva C, Illan M, Lamuela R. 2012. Oil matrix effects on plasma exposure and urinary excretion of phenolic compounds from tomato sauces: evidence from human pilot study. Food Chem. 130, 581-590. https://doi.org/10.1016/j.foodchem.2011.07.078