Response surface optimization for recovery of polyphenols and carotenoids from leaves of Centella asiatica using an ethanol‐based solvent system

Response surface methodology has been used to optimize the extraction conditions for total phenolics and carotenoids from leaves of Centella asiatica. Solvent concentration (30%–100%), extraction temperature (30–60°C), and extraction time (30–90 min) were used as the independent variables. A second‐order polynomial model produced a satisfactory fitting of the experimental data with regard to total phenolics (R (2) = 84.75%, p < 0.004) and carotenoid (R (2) = 78.74, p < 0.019) contents. The optimum extraction conditions of ethanol concentration, extraction temperature, and extraction time for phenolics were 6.1%, 70.2°C, and 110.5 min and for carotenoids, the optimum parameters were 100%, 70.2°C, and 110.5 min, respectively. The optimal predicted contents for total phenolics (9.03 mg Gallic Acid Equivalent (GAE)/g DW) and carotenoid (8.74 mg/g DW) values in the extracts were agreed with the experimental values obtained with optimum extraction conditions for each response, and also they possess significantly higher total antioxidant capacity.