Investigation of microwave-assisted extraction of phenolic compounds from raspberry (Rubus idaeus L.) and its antioxidant activity

Objective To optimize the process for the microwave-assisted extraction(MAE) of phenolic compounds and evaluate the antioxidant activity of the MAE extract by scavenging capability.Methods The effects of ethanol concentration,extraction temperature,extraction time and liquid to solid ratio on phenolic compounds yield were investigated by single factor method,and then orthogonal design was employed to optimize condition.In addition,the antioxidant activities of the MAE extract were evaluated in vitro by scavenging capability of DPPH and ABTS free radical.Results The optimal condition obtained was as follows:ethanol concentration was 50%,microwave extraction time was 10 min,extraction temperature was 80℃,and ratio of liquid to solid was 20 mL·g~(-1),the extraction yield was 0.408%.DPPH and ABTS radical scavenging experiment showed that the phenolic compounds had significant antioxidant activity.Conclusions MAE is proved to be an effective method for phenolic compounds extraction and the extract of MAE shows higher antioxidant activity than trolox,which makes this fruit a good source of antioxidant in health-care food and pharmaceutical industry.