Optimisation of the solvent extraction of bioactive compounds from Parkia speciosa pod using response surface methodology

Central composite design was employed to optimise the buffer-to-solids ratio (X1: 20–50 ml/g), incubation temperature (X2: 35–55 °C) and time (X3: 100–200 min), obtaining extracts from Parkia speciosa pod with high total phenolic and flavonoid contents and high antioxidant activities. Analysis of variance showed that the contribution of a quadratic model was significant for the responses. An optimisation study using response surface methodology was performed and 3D response surfaces were plotted from the mathematical models. The optimal conditions based on combination responses were: X1 = 20 ml/g, X2 = 35–36 °C and X3 = 100–102 min. These optimum conditions yielded total phenolic contents of 664–668 mg gallic acid equivalents/100 g, total flavonoid contents of 47.4–49.6 mg pyrocatechol equivalents/100 g, %DPPHsc of 81.2–82.1%, %ABTSsc of 78.2–79.8% and FRAP values of 3.2–3.3 mM. Close agreement between experimental and predicted values was found. This methodology could be applied in the extraction of bioactive compounds in the natural product industry.