Optimization of microwave-assisted extraction of polyphenols from mulberry fruits (Morus alba L.) using response surface methodology

Polyphenols in mulberry fruit were fast extracted using a microwave-assisted extraction technique, and the effects of process variables including the solvent concentration, irradiation time, microwave power, and solvent consumption upon polyphenol extraction were investigated. Fifteen runs rotatable box-behnken design (RBBD) with three variables and three levels were employed; optimal conditions and maximal yields of the total polyphenol and flavonoid contents were predicted by generating a mathematical polynomial model based on response surface methodology. The estimated optimal conditions were ethanol concentration of 40%, irradiation time of 8 min, and microwave power of 210 W. A verification experiment was carried out at the above mentioned optimal conditions, and no significant differences were observed between the predicted and experimental values, which confirmed that the prediction was valid and application of response surface methodology (RSM) to the extraction of polyphenols and flavonoids from mulberries under microwaveassisted extraction (MAE) process was successful. In addition, specific polyphenols contained in mulberries were identified and quantified using high performance liquid chromatograph.