Process Conditions Optimization for Extraction of Total Phenolic Contents and Antioxidant Activity of Methanolic Extract of an Iranian Date using Response Surface Methodology (RSM)

Antioxidants are the molecules that can scavenge reactive free radicals and prevent the other molecules from oxidation. So, they contribute an important role to prevent of various diseases. Studies show that in addition to the nutritional values of dates, the fruit extracts have the potential to scavenge free radicals due to the presence of antioxidant compounds. The aim of this study is statistical analysis and to optimize extraction process conditions of an Iranian date using Response Surface Methodology (RSM), for the first time. Methanol has been used as the extraction solvent. The independent variables include extraction time (30-60-90 min), temperature (30-50-70 0C), solvent to solid ratio (10-25-40 cc/g), and solvent percentage (10-50-90) min. Total phenolic contents and antioxidant activity of the extracts have been considered as response variables. Box-Behnken design and Response Surface Methodology have been used to determine the parameters levels and modeling the responses, respectively. The results show that the optimal conditions to maximize total phenolic contents and antioxidant activity of date extract, include extraction time, 90 min, temperature, 70 0C, solvent to solid ratio, 39.89 cc/gr, solvent percentage, 10.11 (V/V), resulting in total phenolic contents and antioxidant activity of date extract in 633.36 mg(GAE)/100g(FW), and 59.46 % (based on DPPH radical scavenge). The predicted conditions are in good agreement with the experimental data, indicating the model accuracy.