Effects of processing conditions on microwave extraction of total flavonoids from bitter almond skin and optimization of response surface methodology

[Objective]The experiment was conducted to optimize the process conditions for extraction of flavonoids from bitter almond's skin in order to utilize the unexplored resources. [Method]A new methodology for microwave extraction of flavonoids was developed and used, and the effects of various factors and processing conditions on flavonoid concentration was observed and analyzed through response surface methodology(RSM). [Results]The optimal conditions for flavonoids extraction process included the use of 68% ethanol with 23∶1(vol/wt) liquid to solid ratio for 5 min extraction duration. Under these conditions, the extraction rate of total flavonoids from bitter almond skin was recorded as 15.198 mg/g. [Conclusion]The process of microwave extraction was found not only simple but also economic and time saving, which may provided new directions for industrial use of bitter almond skin.