Optimization of the Ultrahigh-Pressure–Assisted Extraction of Phenolic Compounds and Antioxidant Activity from Palm Dates (Phoenix dactylifera L.)

The goal of this study was to optimize an innovative ultrahigh-pressure–assisted extraction method for phenolic compounds of date palm (Phoenix dactylifera L.) using response surface methodology (RSM). A four-factor-three-level Box–Behnken design (BBD) was used to test the following extraction parameters: ethanol concentration (X1), solvent to sample ratio (X2), temperature (X3), and pressure (X4). Analysis of variance (ANOVA) results revealed that the main treatment X1, X2, and X4 significantly affected extraction yield, while X3 did not. The optimum response for the combination of phenolic compounds and antioxidant activity was obtained with following extraction parameters predicted by the model: X1 = 60.54% (v/v), X2 = 70 mL/g, X3 = 65 °C, and X4 = 600 MPa. These parameters were validated in an additional experiment carried out under the optimal conditions given by experimental results; the experimental values obtained were in close agreement with the predicted values. This suggests that the RSM BBD model described in this work is an efficient quantitative tool to predict the extraction efficiency of polyphenols and antioxidants capacity from date palm fruit.