Abstract

Effects of gamma ray irradiation on olive fruits quality, enzyme activities and issued oil

Author(s): Sonia Mejri, Yassine Mabrouk,Taieb Jerbi, Samira Sifi, Mouldi Saidi , Mohamed Gargouri

The results described in the present work concern the study of changes in gamma ray irradiated olive fruit (Tunisian variety: “Chemlali”) quality along the storage time processing and the quality of olive oil issued. The study focused on the changes related to microbiological and physico-chemical properties, aswell as pectinase activities in olives after irradiation.We also have been interested in the final product quality after oil extraction. The results of non irradiated olives were presented for comparative purposes. Mature olive fruits were treated with 0.5, 1 and 1.5 kGy  ray radiation. Olive fruits were then stored for one month. Irradiation at 1.5 kGy allows the almost total destruction of the total aerobic germs, yeasts and moulds. Concerning physico-chemical parameters, the  ray dose level enhancement generated an improvement in water retention capacity and then decreased the rate of polysaccharide hydrolysis in olives. Moreover, the irradiation dose of 0.5 kGy induced an increase in pectinase activities and the improvement of the protein extraction yield. The  ray irradiation of olive fruit seems to not decrease olive oil oxidative stability in the studied samples. Finally,  ray radiationwas able to improve the yield of extraction of the oil (from20.85 to 22.7%) and insaponifiable fraction as polyphenols and beta carotenes.