Exploiting Response Surface Methodology (RSM) as a Novel Approach for the Optimization of Phenolic and Antioxidant Activity of Date Palm Fruit

The Box-Behnken design was used to investigate the effect of three independent variables – time, temperature and solvent-to-solid ratio on the responses of total phenolics, total flavonoids, 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity and cupric ion reducing antioxidant capacity (CUPRAC) of date fruit methanolic extracts. Response surface analysis showed that the optimal ultrasound extraction parameters that maximized the responses were 30 min, 298 K and 74.4 ml/g. Under optimum conditions, UHPLC-DAD-MS/MS was used to tentatively characterize 11 phenolic compounds.