Microwave assisted extraction of secondary metabolites from plants: Current status and future directions

Plant secondary metabolites are known to be an important source of foods, fragrances, pigment, drugs and so on. Extraction is one of the crucial steps for research and development of plant secondary metabolites. Over the past 25 years, a large number of manuscripts of microwave assisted extraction have been published and lots of remarkable results have been achieved. However, there are still many theoretical and technical barriers in the area of microwave assisted extraction of plant secondary metabolites, which need to be overcome. This paper reviews recent advances in microwave assisted extraction of plant secondary metabolites, such as flavonoids, quinones, phenylpropanoids, terpenoids and alkaloids. Principles and mechanisms, apparatuses and equipment, advantages and disadvantages of microwave assisted extraction are also summarized. The last part of the paper introduces new and emerging technologies of microwave technique, and then suggests strategies for further research into microwave assisted extraction of plant secondary metabolites.