From Field to Shelf: How Microwave-Assisted Extraction Techniques Foster an Integrated Green Approach

Abstract

Microwave-assisted extraction of organic compounds from vegetal matrixes is a relatively young field of research. The exceptional results achievable at the laboratory scale by microwave-assisted extraction, like shorter extraction times, lower average temperatures, reduction of organic solvents use, higher yields and selectivity, as well as energy and cost saving, are not always accompanied by a successful scale up. Nevertheless, microwave-assisted techniques of extraction have been multiplying during last decades. In this framework, a deeper knowledge of microwave applicator design criteria is mandatory. This chapter starts from the basis of microwave heating and the relevant material properties involved in a successful microwave-assisted extraction application, to continue with a short overview on how such properties can be measured and used to optimize the experimental setup or a possible scale up of the process under investigation. A comprehensive review of recent applications of microwave-assisted extraction, applied to vegetal matrixes, is presented next. The chapter ends reviewing duplex treatments of vegetal matrixes for extraction purposes, where microwave heating is coupled to other techniques, like ultrasounds, and indicating new paths, where the recent advent of new microwave solid-state generators has led to better process control and higher yields and energy efficiency.