Main Article Content
enrichment, DPPH, olive leaf, phenolic compounds, radical scavenging
The antioxidant role of olive leaves obtained from Adana Topagi, Adana Yerli, Domat and Gemlik cultivars during olive ripening were investigated and compared to commercial olive leaf extract (OLE) as well as butylated hydroxyl toluene (BHT) and butylated hydroxyl aniline (BHA) as synthetic antioxidants. The results showed that total phenol contents of OLEs reduced 44 to 63% during ripening. OLEs, irrespective of cultivar and harvest date were found to be good sources of radical scavengers (P<0.05). The radical scavenging activity of OLEs at 100 or 200 ?g/g were higher than BHT (P<0.05) and similar or lower than BHA (P?0.05). The addition of Domat and Adana Topagi OLEs at 100 or 200 ?g/g to refined olive oil increased oxidative stability and caused to extracts to show better activity than commercial OLE but lower or similar activity than that of BHT and BHA (P?0.05) during different harvest times. BHA and BHT were the most effective antioxidants employed to delay the bulk oil oxidation but Domat and Adana Topagi olive leaves may have food additive value to slow down the progress of lipid oxidation and increase oxidative stability in refined olive oil. Due to concerns regarding the safety and toxicity of synthetic antioxidants, olive leaves may prove useful as safe, natural, functional ingredients with health promoting properties to food industry. Enrichment of oils or oil containing foods with the extracts from olive leaves and therefore, improving quality and healthiness of the target oils suggests a future possible use of them as a natural antioxidant and as an ingredient at an industrial scale since they seem to be useful for lipid stabilisation.
Artajo, L.S., Romero, M.P., Morello, J.R. and Motilva, M.J., 2006. Enrichment of refined olive oil with phenolic compounds: evaluation of their antioxidant activity and their effect on the bitter index. Journal of Agricultural and Food Chemistry 54: 6079-6088.
Bahloul, N., Boudhrioua, N.N., Kouhila, M. and Kechaou, N., 2009. Effect of convective solar drying on colour, total phenols and radical scavenging activity of olive leaves (Olea europaea L.). International Journal of Food Science & Technology 44: 2561-2567.
Barreira, J., Ferreira, I., Oliveira, M. and Pereira, J., 2008. Antioxidant activities of the extracts from chestnut flower, leaf, skins and fruit. Food Chemistry 107: 1106-1113.
Benavente-Garcia, O., Castillo, J., Lorente, J., Ortuno, A. and Del Rio, J.A., 2000. Antioxidant activity of phenolics extracted from Olea europea L. leaves. Food Chemistry 68: 457-462.
Bouaziz, M., Feki, I., Ayadi, M., Jemai, H. and Sayadi, S., 2010. Stability of refined olive oil and olive-pomace oil added by phenolic compounds from olive leaves. European Journal of Lipid Science and Technology 112: 894-905.
Bouaziz, M., Fki, I., Jemai, H., Ayadi, M. and Sayadi, S., 2008. Effect of storage on refined and husk olive oils composition: stabilization by addition of natural antioxidants from Chemlali olive leaves. Food Chemistry 108: 253-262.
Bouaziz, M. and Sayadi, S., 2005. Isolation and evaluation of antioxidants from leaves of a Tunisian cultivar olive tree. European JournalofLipid ScienceandTechnology 107: 497-504.
Boudhrioua, N., Bahloul, N., Ben Slimen, I. and Kechaou, N., 2009. Comparison on the total phenol contents and the color of fresh and infrared dried olive leaves. Industrial Crops and Products 29: 412-419.
Cerretani, L. and Bendini, A., 2010. Rapid assays to evaluate the antioxidant capacity of phenols in virgin olive oil. In: Preedy, V.R. and Watson, R.R. (eds.) Olives and olive oil in health and disease prevention. Elsevier, Amsterdam, the Netherlands, pp. 625-633.
De Abreu, D.A.P., Rodríguez, K.V. and Cruz Freire, J.M., 2011. Effectiveness of antioxidants on lipid oxidation and lipid hydrolysis of cod liver oil. European Journal of Lipid Science and Technology 113: 1395-1401.
De Medina, V.S., Priego-Capote, F., Jimenez-Ot, C. and de Castro, M.D.L., 2011. Quality and stability of edible oils enriched with hydrophilic antioxidants from the olive tree: the role of enrichment extracts and lipid composition. Journal of Agricultural and Food Chemistry 59: 11432-11441.
Decker, E.A., Warner, K., Richards, M.P. and Shahidi, F., 2005. Measuring antioxidant effectiveness in food. Journal of Agricultural and Food Chemistry 53: 4303-4310.
Farag, R.S., El-Baroty, G.S. and Basuny, A.M., 2003. The influence of phenolic extracts obtained from the olive plant (cvs. Picual and Kronakii), on the stability of sunflower oil. International Journal of Food Science and Technology 38: 81-87.
Ferreira, I.C.F.R., Barros, L., Soares, M.E., Bastos, M.L. and Pereira, J.A., 2007. Antioxidant activity and phenolic contents of Olea europaea L. leaves sprayed with different copper formulations. Food Chemistry 103: 188-195.
Firestone, D. (ed.), 1989. Official methods and recommended practices of the AOCS. American Oil Chemists’ Society (AOCS), Champaign, IL, USA.
Giao, M.S., Gonzalez-Sanjose, M.L., Rivero-Perez, M.D., Pereira, C.I., Pintado, M.E. and Malcata, F.X., 2007. Infusions of Portuguese medicinal plants: dependence of final antioxidant capacity and phenol content on extraction features. Journal of the Science of Food and Agriculture 87: 2638-2647.
Goulas, V., Papoti, V.T., Exarchou, V., Tsimidou, M.Z. and Gerothanassis, I.P., 2010. Contribution of flavonoids to the overall radical scavenging activity of olive (Olea europaea L.) leaf polar extracts. Journal of Agricultural and Food Chemistry 58: 3303-3308.
Gutfinger, T., 1981. Polyphenols in olive oils. Journal of the American Oil Chemists’ Society 58: 966-968.
Hayes, J.E., Stepanyan, V., Allen, P., O’Grady, M.N. and Kerry, J.P., 2010. Effect of lutein, sesamol, ellagic acid and olive leaf extract on the quality and shelf-life stability of packaged raw minced beef patties. Meat Science 84: 613-620.
Jemai, H., El-Feki, A. and Sayadi, S., 2009. Antidiabetic and antioxidant effects of hydroxytyrosol and oleuropein from olive leaves in alloxan-diabetic rats. Journal of Agricultural and Food Chemistry 57: 8798-8804.
Jimenez, P., Masson, L., Barriga, A., Chávez, J. and Robert, P., 2011. Oxidative stability of oils containing olive leaf extracts obtained by pressure, supercritical and solvent-extraction. European Journal of Lipid Science and Technology 113: 497-505.
Katsube, T., Tabata, H., Ohta, Y., Yamasaki, Y., Anuurad, E., Sh?waku, K. and Yamane, Y., 2004. Screening for antioxidant activity in edible plant products: comparison of low-density lipoprotein oxidation assay, DPPH radical scavenging assay, and folin-ciocalteu assay. Journal of Agricultural and Food Chemistry 52: 2391-2396.
Kiritsakis, K., Kontominas, M.G., Kontogiorgis, C., Hadjipavlou-Litina, D., Moustakas, A. and Kiritsakis, A., 2009. Composition and antioxidant activity of olive leaf extracts from greek olive cultivars. Journal of the American Oil Chemists’ Society 87: 369-376.
Kontogianni, V.G. and Gerothanassis, I.P., 2012. Phenolic compounds and antioxidant activity of olive leaf extracts. Natural ProductResearch 26: 186-189.
Lambropoulos, I. and Roussis, I.G., 2007. Antioxidant activity of red wine phenolic extracts towards oxidation of corn oil. European Journal of Lipid Science and Technology 109: 623-628.
Lee, O.H. and Lee, B.Y., 2010. Antioxidant and antimicrobial activities of individual and combined phenolics in Olea europaea leaf extract. Bioresoure Technology 101: 3751-3754.
Morello, J.R., Vuorela, S., Romero, M.P., Motilva, M.J. and Heinonen, M., 2005. Antioxidant activity of olive pulp and olive oil phenolic compounds of the arbequina cultivar. Journal of Agricultural and Food Chemistry 53: 2002-2008.
Nissiotis, M. and Tasioula-Margari, M., 2002. Changes in antioxidant concentration of virgin olive oil during thermal oxidation. Food Chemistry 77: 371-376.
Orozco-Solano, M.I., Priego-Capote, F. and Luque de Castro, M.D., 2011. Influence of simulated deep frying on the antioxidant fraction of vegetable oils after enrichment with extracts from olive oil pomace. Journal of Agricultural and Food Chemistry 59: 9806-9814.
Ortega-García, F. and Peragón, J., 2010. Phenol metabolism in the leaves of the olive tree (Olea europaea L.) cv. Picual, Verdial, Arbequina, and Frantoio during ripening. Journal of Agricultural and Food Chemistry 58: 12440-12448.
Paiva-Martins, F.C., Correira, R., Felix, S., Ferreira, F. and Gordon, M.H., 2007. Effects of enrichment of refined olive oil with phenolic compounds from olive leaves. Journal of Agricultural and Food Chemistry 55: 4139-4143.
Papoti, V.T. and Tsimidou, M.Z., 2009a. Impact of sampling parameters on the radical scavenging potential of olive (Olea europaea L.) leaves. Journal of Agricultural and Food Chemistry 57: 3470-3477.
Papoti, V.T. and Tsimidou, M.Z., 2009b. Looking through the qualities of a fluorimetric assay for the total phenol content estimation in virgin olive oil, olive fruit or leaf polar extract. Food Chemistry 112: 246-252.
Rafiee, Z.J., Jafari, S.M., Alami, M. and Khomeiri, M., 2012. Antioxidant effect of microwave-assisted extracts of olive leaves on sunflower oil. Journal of Agricultural Science and Technology. 14: 1497-1509.
Rotondi, A. and Magli, M., 2004. Ripening of olives var. Correggiolo: modification of oxidative stability of oils during fruit ripening and oil storage. Journal of Food, Agriculture & Environment 2: 193-199.
Roussis, I.G., Tzimas, P.C. and Soulti, K., 2008. Antioxidant activity of white wine extracts and some phenolic acids toward corn oil oxidation. Journal of Food Processing and Preservation 32: 535-545.
Salta, F.N., Mylona, A., Chiou, A., Boskou, G. and Andrikopoulos, N.K., 2007. Oxidative stability of edible vegetable oils enriched in polyphenols with olive leaf extract. Food Science and Technology International 13: 413-421.
Soulti, K. and Roussis, I.G., 2007. Inhibition of butter oxidation by some phenolics. European Journal of Lipid Science and Technology 109: 706-709.
Suárez, M., Romero, M.-P., Ramo, T. and Motilva, M.-J., 2011. Stability of a phenol-enriched olive oil during storage. European Journal of Lipid Science and Technology 113: 894-903.
Sudjana, A.N., D’Orazio, C., Ryan, V., Rasool, N., Ng, J., Islam, N., Riley, T.V. and Hammer, K.A., 2009. Antimicrobial activity of commercial Olea europaea (olive) leaf extract. International Journal of Antimicrobial Agents33: 461-463.