Ultrasonic-assisted extraction of total phenolic contents from Phoenix dactylifera and evaluation of antioxidant activity: statistical optimization of extraction process parameters

The present study aimed to optimize extraction conditions of total phenolic contents (TPC) and evaluation of antioxidant activity (AA) of date palm fruit. The Box–Behnken design was used to study effects of three independent variables, acetone concentration (40–80%), sonication amplitude (50–100%), and extraction time (15–35 min). The statistical optimization revealed that extraction with acetone concentration of 66.71% (v/v) for 29.58 min with sonication amplitude of 64.78% were the best combination of these variables. The corresponding experimental values for both TPC and AA were 725.33 and 39.61 mg GAE/100 g DM of date fruit, respectively. Predicted values were in close agreement with experimental ones. Elaborated models were significant (P > 0.05) with high regression coefficients (R2 ≥ 0.9) and insignificant lack of fits that confirm the validity and success of both MRS models to optimize extraction conditions of antioxidants date fruit.