The Effect of Extraction Conditions on Antioxidant Properties of Zizyphus Fruit and Date Kernel Var. Mazafati

Antioxidants are compounds that absorb free radicals and reduce the rate of oxidation, spoilage, colour changes and in general oxidative rancidity. The application of synthetic antioxidants has been limited for their possible side effects, therefore scientists have been searching for alternatives from natural sources. The aim of this study is to determine the optimum conditions to obtain date kernel and zizyphus fruit extracts.
In this study, 9 solvent systems (3 single component solvent systems including water, ethanol and methanol and 6 two components solvent systems including water 50: ethanol 50, water 50: methanol 50, water 20: ethanol 80, water 80: ethanol 20 ,water 20: methanol 80 and water 80: methanol 20) at three time periods of 3, 5 and 7 hours in a shaking incubator with a stirring speed of 280 rpm were employed and the amount of extracted phenolic compounds were compared. After choosing the selected treatments evaluation of antioxidant activities concerning DPPH free radical scavenging, total antioxidant capacity and reducing power were performed.
the best solvent systems for zizyphus fruit extractions were water 50: ethanol 50 for two time periods of 5 and 7 hours and for date kernel extraction were water 50: ethanol 50 and water 20: ethanol 80 and ethanol for time period of 7 hours. All these extraction treatment were evaluated using antioxidant tests and solvent extraction system of water 50: ethanol 50 for period of 7 hours were selected as the best treatment.
The results indicated that the solvent mixture consisting of polar and non-polar solvents had greater ability in extraction of phenolic compounds.