Intensification of microwave energy parameters and main effect analysis of total phenolics recovery from Euphorbia hirta leaf

Euphorbia Hirta is an herbaceous plant that has been traditionally applied for the treatment of various ailments due to its phenolic-rich constituents. These important bioactive phenolic contents are often lost during the microwave extraction if the inherent energy parameters are not well controlled. The average power density (APD) and average energy density (AED) are the two energy functions that determine to a larger extent the preservation of thermally unstable phenolic content and physicochemical characteristics of E. hirta. In this study, the parameter effects of microwave extraction variables on the total phenolic content and energy functions were carefully investigated. An iterative single factor and two-level factorial experimental matrix were designed to determine the effects of five parameters on the total phenolic concentrations (TPC) and energy functions (AED and APD). On the overall, the result obtained indicated that the reactor temperature is the most significant factors above the Bonferroni limits of 4.69794, 5.24742 and 3.18245 for the TPC, APD, and AED, respectively. Moreover, the interaction between the microwave power and the solvent loading was adjudged as the most significant interactions. The incorporation of main effects and interaction terms into the empirical model, therefore, revealed a significant contribution of the extraction model. This could, therefore, be used as the basis for further study in the investigation of the parameters of microwave reflux extraction.