Olive leaves (Kronakii cultivar) were obtained from the annual pruning of olive
trees and pressed to obtain a crude juice. An aliquots from the concentrated crude
olive leave juice, represent 400, 600, 1600 and 2400 ppm as polyphenols, were
added to sunflower oil. Samples of sunflower oil mixed with olive leaves juice were
intermittent heated at 180°C ± 5 for 5 hr I day and the heating process was repeated
for 5 consecutive days. A control experiment was performed where butylated hydroxyl
toluene (BHT) at 200 ppm was added to sunflower oil perior to intermittent heating in
order to compare the antioxidant efficiency between the natural polyphenolics of olive
juice and synthetic antioxidant BHT. Some physical (refractive index, smoke point, color and viscosity) and
chemical (acid value, peroxide value, iodine value, thiobarbituric acid value,
saponification number, oxidized fatty acid level and polymer content) constants for the
unheated and heated sunflower oil were determined. The data indicated that the
addition of olive leave juice to heated sunflower oil induced remarkable antioxidant
activity and at 800 ppm level were superior to that of BHT is increasing sunflower oil
stability.