**6. Conclusions**

Microwave-assisted extraction (MAE) of naturally occurring chemical compounds is an extremely efficient extraction technique mainly as a consequence of the unique heating mechanism that is able to generate peculiar and otherwise impossible to reach extraction mechanisms. Different variants of MAE can be though according to the system matrix-solvent to be employed. Indeed, the choice of the kind of MAE technique to be applied, cannot discern from a fundamental aspect to be considered, that is represented by the detailed knowledge of the dielectric properties of the matrix as well as the solvent, to be used. They represent important parameters to be used as input information for numerical simulation studies aimed at predict the microwave power distribution and the temperature evolution into the load during the extraction process.

Numerical simulation is fundamental also since it allows to rapidly select the optimal dimensions of the microwave cavity for a particular load (with particular dielectric properties).

In this view, it can be seen in a process intensification perspective.

In the same perspective, MAE has been shown to significantly benefit from the coupling of a different number of integrating technologies and tools.

However, it has been shown that although MAE can effectively and quantitatively considered greener with respect to conventional soxhlet-based extraction, for example, in the case of lab-scale extraction of curcumin molecule, general conclusions cannot be drawn, since case to case evaluations are mandatory. The use of cradle to the grave LCA evaluation is highly recommended to reach such assessments.
