Olive Leaf Extract as Natural Antioxidant Additive of Fresh Hamburger Stored at 4°C Running Title: Antioxidants from Olive Leaves in Hamburger

Oxidation is one of the major problems that cause hamburger deterioration. Antioxidants are used to prevent or delay oxidation process. The chemical preservatives or antioxidants are not safe and have harmful effects to human health. Currently there is a trend to use natural antioxidants in industry since they are considered as safe compared to chemical ones. The objective of this study was to evaluate the usage of olive leaf extract as well as oleuropein as natural antioxidant additives in fresh hamburger stored at 4°C. Results proved the activity of oleuropein and olive leaves extract as natural antioxidants retarded oxidation of hamburger compared to control samples (without antioxidants). 0.5% of oleuropein and 1.5% of olive leaves extract is the best concentration to be used in fresh hamburger