Green Extraction of Polyphenols from Olive Flesh, Pits and Leaves by Supercritical CO₂

Abstract

Olive flesh, pits and olive leaves obtained from the olive tree (Olea europaea L.) contain compounds rich in polyphenols. Olive flesh, olive pomace and olive leaf oils and extracts are complex mixtures containing more than a hundred compounds with different chemical structures. Freeze drying is an effective preservation technique that produces high-quality dried materials while maintaining the integrity of heat-sensitive compounds. This study aimed to identify and quantify the active phenolic components of oils and extracts from olive flesh, olive pits and olive leaves using supercritical fluid extraction (SFE). An additional co-solvent was used in the SFE process. Extraction yields and total polyphenol contents were determined and are as follows; olive flesh CO2 (OF-1) 32.11%, 527 mg/kg, olive flesh CO2+ethanol (OF-2) 54.21%, 1470 mg/kg, olive pith CO2 (OP-1) 5.79%, 354 mg/kg, olive pith CO2+ethanol (OP-2) 5.85%, 1180 mg/kg and olive leaf CO2 (OL-1) 4.46%, 485 mg/kg, olive leaf CO2+ethanol (OL-2) 6.26%, 1275 mg/kg. Additionally, elevated concentrations of specific phenolic compounds—including 3-hydroxytyrosol, protocatechuic acid, 3-hydroxybenzoic acid, 4-hydroxybenzoic acid, vanillin, ferulic acid, pinoresinol, oleuropein, kaempferol, and 2,5-dihydroxybenzoic acid—were exclusively detected in the OL-2 sample. Kaempferol was not detected in OL-1 and all other compounds were observed in small amounts in both analyses. OL-1 and OL-2 extracts showed antioxidant activity. In each case, extraction yields, total polyphenol contents and levels of phenolic compounds from olive leaves were relatively high. Polat SFE systems show promise as a sustainable and environmentally friendly extraction technology for future applications.

Keywords

• Olive flesh
• Olive pith
• Olive leaf
• Phenolic compounds
• Freeze drying
• Supercritical fluid extraction.

References

1. Al-Otoom, A., Al-Asheh, S., Allawzi, M., Mahshi, K., Alzenati, N., Banat, B., & Alnimr, B. (2014). Extraction of oil from uncrushed olives using supercritical fluid extraction method. J. Supercrit. Fluids, 95, 512–518. https://doi.org/10.1016/j.supflu.2014.10.023.
2. Baldino, L., Della Porta, G., Osseo, L.S., Reverchon, E., & Adami, R. (2018). Concentrated oleuropein powder from olive leaves using alcoholic extraction and supercritical CO2 assisted extraction. J. Supercrit. Fluids, 133, 65–69. https://doi.org/10.1016/j.supflu.2017.09.026.
3. Belbaki, A., Louaer, W., & Meniai, A.H. (2017). Supercritical CO2 extraction of oil from Crushed Algerian olives. The Journal of Supercritical Fluids, 130, 165-171. https://doi.org/10.1016/j.supflu.2017.08.005.
4. Bengana, M., Bakhouche, A., Lozano-Sánchez, J., Amir, Y., Youyou, A., Segura-Carretero, A., & Fernández-Gutiérrez, A. (2013). Influence of olive ripeness on chemical properties and phenolic composition of Chemlal extra-virgin olive oil. Food Res. Int. 54, 1868–1875. https://doi.org/10.1016/j.foodres.2013.08.037.
5. Bonacci, S., Di Gioia, M.L., Costanzo, P., Maiuolo, L., Tallarico, S., & Nardi, M. (2020). Natural Deep Eutectic Solvent as Extraction Media or the Main Phenolic Compounds from Olive Oil Processing Wastes. Antioxidants, 9, 513. https://doi.org/10.3390/antiox9060513.
6. Burgaz, O., Yıldırım, İ., Baycan, A., Giziroğlu, E., Şimşek, E., & Polat, İ. (2024). Extraction of phenolic compounds and antioxidant activity analysis of Ficus carica L. seed oil using supercritical fluid technology. International Journal of Plant Based Pharmaceuticals, 4(2), 125–130. https://doi.org/10.62313/ijpbp.2024.251.
7. Canabarro, N.I., Mazutti, M.A., & do Carmo Ferreira, M. (2019). Drying of olive (Olea europaea L.) leaves on a conveyor belt for supercritical extraction of bioactive compounds: Mathematical modeling of drying/extraction operations and analysis of extracts. Ind. Crops Prod, 136, 140–151. https://doi.org/10.1016/j.indcrop.2019.05.004.
8. Cavaca, L.A.S., & Afonso, C.A.M. (2018). Oleuropein: A Valuable Bio-Renewable Synthetic Building Block. Eur. J. Org. Chem, 581–589. https://doi.org/10.1002/ejoc.201701136.

9. Clodoveo, M.L., Crupi, P., Annunziato, A., & Corbo, F. (2022). Innovative Extraction Technologies for Development of Functional Ingredients Based on Polyphenols from Olive Leaves. Foods, 11, 103. https://doi.org/10.3390/foods11010103.
10. Dauber, C., Carreras, T., González, L., Gámbaro, A., Valdés, A., Ibañez, E., & Vieitez, I. (2022). Characterization and incorporation of extracts from olive leaves obtained through maceration and supercritical extraction in Canola oil: Oxidative stability evaluation. LWT—Food Sci. Technol, 160, 113274. https://doi.org/10.1016/j.lwt.2022.113274.
11. da Silva, R. P. F. F., Rocha-Santos, T. A. P., & Duarte, A. C. (2016). Supercritical fluid extraction of bioactive compounds. Trends in Analytical Chemistry, 76, 40–51. https://doi.org/10.1016/j.trac.2015.11.013.
12. European Commission. (n.d.). Olive oil in the EU. Directorate General for Agriculture and Rural Development. https://agriculture.ec.europa.eu/farming/crop-productions-and-plant-based-products/olive-oil_en
13. Felicia, W. X. L., Rovina, K., Aqilah, N. M. N., & Jaziri, A. A. (2024). Optimisation of supercritical fluid extraction of orange (Citrus sinenis L.) peel essential oil and its physicochemical properties. Current Research in Green and Sustainable Chemistry, 8, 100410. https://doi.org/10.1016/j.crgsc.2024.100410.
14. Guinda, A. (2006). Use of solid residue from the olive industry. Grasas Y. Aceites, 57, 107–115. https://doi.org/10.1002/chin.200647274.
15. Ianni, A., Innosa, D., Oliva, E., Bennato, F., Grotta, L., Saletti, M. A., Pomilio, F., Sergi, M., & Martino, G. (2021). Effect of olive leaves feeding on phenolic composition and lipolytic volatile profile in goat milk. J. Dairy Sci. 104, 8835–8845. https://doi.org/10.3168/jds.2021-20211.
16. Igual, M., Cebadera, L., Cámara, R.M., Agudelo, C., Martínez-Navarrete, N., & Cámara, M. (2019). Novel Ingredients Based on Grapefruit Freeze-Dried Formulations: Nutritional and Bioactive Value. Foods, 8, 506. https://doi.org/10.3390/foods8100506.
17. Khalil, A.A., Rahman, M.M., Rauf, A., Islam, M.R., Manna, S.J., Khan, A.A., Ullah, S., Akhtar, M.N., Aljohani, A.S.M., Al Abdulmonem, W., & Simal-Gandara, J. (2023). Oleuropein: Chemistry, Extraction Techniques and Nutraceutical Perspectives—An Update. Crit. Rev. Food Sci. Nutr, 64, 9933–9954. https://doi.org/10.1080/10408398.2023.2218495.
18. Kountouri, A.M., Mylona, A., Kaliora, A.C., & Andrikopoulos, N.K. (2007). Bioavailability of the Phenolic Compounds of the Fruits (Drupes) of Olea europaea (Olives): Impact on Plasma Antioxidant Status in Humans. Phytomedicine, 14, 659–667. https://doi.org/10.1016/j.phymed.2007.06.001.
19. Kyriakoudi, A., Mourtzinos, I., Tyśkiewicz, K., & Milovanovic, S. (2024). An Eco-Friendly Supercritical CO2 Recovery of Value-Added Extracts from Olea europaea Leaves. Foods, 13, 1836. https://doi.org/10.3390/foods13121836.
20. Leone, A., Romaniello, R., Zagaria, R., Sabella, E., De Bellis, L., & Tamborrino, A. (2015). Machining effects of different mechanical crushers on pit particle size and oil drop distribution in olive paste. Eur. J. Lipid Sci. Technol,117,1271–1279. https://doi.org/10.1002/ejlt.201400485.
21. Mosibo, O.K., Laopeng, S., Ferrentino, G., & Scampicchio, M. (2022). Oxidizability of Oils Recovered from Olive Seeds by Isothermal Calorimetry. Foods, 11, 1016. https://doi.org/10.3390/foods11071016.
22. Otero, D.M., Lorini, A., Oliveira, F.M., da Fonseca Antunes, B., Oliveira, R.M., & Zambiazi, R.C. (2021). Leaves of Olea europaea L. as a Source of Oleuropein: Characteristics and Biological Aspects. Res. Soc. Dev, 10, e185101321130. https://doi.org/10.33448/rsd-v10i13.21130.
23. Pazır, F., Ova, G., Alper, Y., & Turan, F. (2019). Extraction of Olive Leaves (Olea Europaea) By Using Supercritical carbon dioxide Extraction Method. International Journal on Mathematic, Engineering and Natural Sciences, 3, 7.
24. Pereira, A.P., Ferreira, I.C.F.R., Marcelino, F., Valentão, P., Andrade, P.B., Seabra, R., Estevinho, L., Bento, A., & Pereira, J.A. (2007). Phenolic compounds and antimicrobial activity of olive (Olea europaea L. Cv. Cobrançosa) leaves. Molecules, 12, 1153–1162. https://doi.org/10.3390/12051153.
25. Rahmanian, N., Jafari, S.M., & Wani, T.A. (2015). Bioactive Profile, Dehydration, Extraction and Application of the Bioactive Components of Olive Leaves. Trends Food Sci. Technol, 42, 150–172. https://doi.org/10.1016/j.tifs.2014.12.009.
26. Ranalli, A., Pollastri, L., Contento, S., Di Loreto, G., Iannucci, E., Lucera, L., & Russi, F. (2002). Acylglycerol and fatty acid components of pulp, seed, and whole olive fruit oils. Their use to characterize fruit variety by chemometrics. J. Agric. Food Chem, 50, 3775–3779. https://doi.org/10.1021/jf011506j.
27. Rodríguez, G., Lama, A., Rodríguez, R., Jiménez, A., Guillén, R., & Fernández-Bolaños, J. (2008). Olive stone an attractive source of bioactive and valuable compounds. Bioresour. Technol, 99, 5261–5269. https://doi.org/10.1016/j.biortech.2007.11.027.
28. Sahin, S., Bilgin, M., & Dramur, M.U. (2011). Investigation of Oleuropein Content in Olive Leaf Extract Obtained by Supercritical Fluid Extraction and Soxhlet Methods. Separation Science and Technology, 46,1829–1837. https://doi.org/10.1080/01496395.2011.573519.
29. Skupień, K., & Oszmiański, J. (2004). Comparison of six cultivars of strawberries (Fragaria x ananassa Duch.) grown in northwest Poland. European Food Research and Technology, 219, 66-70. https://doi.org/10.1007/s00217-004-0918-1.
30. Soler-Rivas, C., Espin, J.C., & Wichers, H.J. (2000). Oleuropein and Related Compounds. J. Sci. Food Agric, 80, 1013–1023. https://doi.org/10.1002/(SICI)1097-0010(20000515)80:7%3C1013::AID-JSFA571%3E3.0.CO;2-C
31. Wang, L., & Weller, C.L. (2006). Recent advances in extraction of nutraceuticals from plants. Trends in Food Science and Technology, 17, 300–312. https://doi.org/10.1016/j.tifs.2005.12.004.