Optimization of process parameters for phenolics extraction of Cratoxylum formosum ssp. formosum leaves by response surface methodology

Leaves of Cratoxylum formosum ssp. formosum (Cff) contain high amounts of phenolic compounds with potential anti-oxidant properties. In this study, the effects of the extraction method on the recovery of phenolic compounds from Cff leaves were investigated. Response surface methodology (RSM) was used to optimize the extraction conditions based on the simultaneous maximization of yields of total phenolics, chlorogenic acid, and antioxidant activity. The extraction conditions were investigated using a central-composite rotatable design of response surface methodology (RSM-CCRD). The independent variables used were ethanol concentration, extraction temperature, and time. The experimental results fitted the model well and the investigated variability was explained. Maximal yields of total phenolics, chlorogenic acid, and the extract with good antioxidant activity were achieved by using an ethanol concentration of 38.83 %v/v, temperature of 59.76 A degrees C, and time of 5.50 h. These conditions gave the extraction yields of total phenolics, chlorogenic acid, and anti-oxidant activity of 43.52 A +/- 3.66 mg gallic acid equivalent (GAE)/g, 119.36 A +/- 6.34 mg/g, and 0.82 A +/- 0.08 mmol trolox equivalents (TE)/g dry powder of plant leaves. The experimental values agreed with those predicted within a 95 % confidence interval, thus indicating the suitability of RSM in optimizing the extraction of phenolics from Cff.