Deployment of response surface methodology to optimize recovery of dried dark fig (Ficus carica L., var. Azenjar) total phenolic compounds and antioxidant activity

Fig fruit (Ficus carica L.) is currently known by its high phenolic contents and antioxidant activity. Considering the importance of this fruit, we set as objective the conditions optimization for extracting total phenolic compounds (TPC) and antioxidant activity from dried dark fig using response surface methodology (RSM). The Box–Behnken design was used to investigate effects of three independent variables, solvent concentration (acetone/water 40–80%), temperature (25–65°C), and time (60–120 min), on the response. Second-order polynomial model was used for predicting the response. Regression analysis showed that about 99% of the variation was explained by the models. Response surface analysis showed that the optimal extraction parameters which maximized antioxidants extraction were 61.03% acetone, 105.12 min, and 46.16°C. Under optimal conditions, experimental values for TPC and antioxidant activity were 454.78 and 38.00 mg gallic acid equivalent (GAE)/100 g dry matter. The experimental values are in accordance with those predicted, indicating the suitability of the employed model and the success of RSM in optimizing the extraction conditions.