THE ABILITY OF OLIVE LEAF EXTRCATS TO ENHANCE THE OXIDATIVE STABILITY OF SUNFLOWER OIL

Document Type : Original Article

Authors

Agric. Chem. Dept. Fac. OF Agric. , MInia Univ. , ELminia Egypt

Abstract

       The present study was undertaken to evaluate the potential of antioxidant activity of olive leaf extracts ( OLEs ) and compared with other natural or synthetic antioxidants .  Different extracts in term of antioxidant properties were studied . Three extracts of olive leaf  were obtained by using ethanol , methanol and water  .So, the  aim  of  this  study  was  to  assess  the effectiveness  of such extracts and compared it with other antioxidants  such as green tea extract , TBHQ , citric acid  on  the  oxidative  stability  of  sunflower oil  during storage at an oven at 63±1°C for  0, 5, 10, 15, 20 days. To follow the relative of oxidative deterioration of sunflower  oil , as well as deteriming the antioxidative activity of various samples. Oils were analyzed periodically for their peroxide value (PV) , iodine value ( IV ) , acid value (AV ) and thiobarbituric acid (T.B.A.). Analysis of  heated sunflower oils demonstrated significant  increases in PV and AV and T.B.A .  However ,  IV of the oils were markedly decreased. On the other hand , ethanol  extract  exhibited  the  highest  antiradical  activity  among  solvents.       
      Results also showed that  the three  extracts of olive leaf   ( i.e. methanolic- , ethanolic- and water- olive leaf  extracts) secured protective effect against oxidation of sunflower  oil and can serve as substitutes for synthetic antioxidants .

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