*2.3.1.2.7 Microwave hydrodiffusion and gravity*

Microwave hydrodiffusion and gravity (MHG) is a new green extraction technique of EOs developed by Vian and collaborators in 2008. This green extraction technique is an original "upside down" microwave alembic combining microwave heating and earth gravity at atmospheric pressure [65]. MHG has become not only an economic and efficient but also an environmental- and eco-friendly, not require water or solvent and as it does require less energy (**Figure 12**) [65, 66].
