Gamma irradiation of air-dried olive leaves: Effective decontamination and impact on the antioxidative properties and on phenolic compounds

Fathia Aouidi; Samia Ayari; Hana Ferhi; Sevastianos Roussos; Moktar Hamdi

doi:10.1016/j.foodchem.2011.01.109

Gamma irradiation of air-dried olive leaves: Effective decontamination and impact on the antioxidative properties and on phenolic compounds

Food Chem. 2011 Aug 1;127(3):1105-13. doi: 10.1016/j.foodchem.2011.01.109. Epub 2011 Feb 2.

Authors

Fathia Aouidi¹, Samia Ayari², Hana Ferhi³, Sevastianos Roussos⁴, Moktar Hamdi³

Affiliations

¹ Laboratory of Microbial Ecology and Technology, Department of Biological and Chemical Engineering, National Institute of Applied Sciences and Technology (INSAT), 2 Boulevard de la Terre, B.P. 676, 1080 Tunis, University of Carthage, Tunisia; Mediterranean Institute of Ecology and Palaeoecology UMR CNRS/IRD 193, IMEP Case 441, FST Saint Jérôme, Université Paul Cézanne, Av. Escadrille Normandie-Niemen, 13397 Marseille cedex 20, France. Electronic address: aouidifathia@yahoo.fr.
² Laboratory of Microbial Ecology and Technology, Department of Biological and Chemical Engineering, National Institute of Applied Sciences and Technology (INSAT), 2 Boulevard de la Terre, B.P. 676, 1080 Tunis, University of Carthage, Tunisia; National Center for Nuclear Sciences and Technologies (CNSTN), Tunis cedex, 2020, Tunisia.
³ Laboratory of Microbial Ecology and Technology, Department of Biological and Chemical Engineering, National Institute of Applied Sciences and Technology (INSAT), 2 Boulevard de la Terre, B.P. 676, 1080 Tunis, University of Carthage, Tunisia.
⁴ Mediterranean Institute of Ecology and Palaeoecology UMR CNRS/IRD 193, IMEP Case 441, FST Saint Jérôme, Université Paul Cézanne, Av. Escadrille Normandie-Niemen, 13397 Marseille cedex 20, France.

PMID: 25214102
DOI: 10.1016/j.foodchem.2011.01.109

Abstract

Olive leaves are commercialized for their antioxidative value due to their valuable phenolic compounds. The present study aimed to evaluate the effect of gamma irradiation on microbial load, on antioxidative properties and on phenolic compounds of air-dried olive leaves. Irradiation was applied up to 25kGy (5kGy intervals) to powdered and intact samples. Total aerobic bacteria, yeast and mold, and lactic acid bacteria were counted after gamma irradiation. Decontamination was obtained at 20kGy. The radioresistance of microbial population was high with D10 values between 9.74 and 25.12kGy. Besides, gamma irradiation up to 25kGy was found to maintain the antioxidant capacity, molecular mass distribution of polyphenolics, total phenolics, ortho-diphenols, flavonoids, oleuropein, verbascoside and rutin contents. To conclude, the improvement of the microbial quality of air-dried olive leaves, without affecting phenolic composition and antioxidative properties, can be successively achieved by the application of gamma irradiation treatment.

Keywords: Antioxidant capacity; D(10)-value; Gamma irradiation; Olive leaf; Phenolic compound.