**2.4 Expression**

This technique of expression or cold pressing essentially concerns the extraction of essential oils from the zest of lemons and oranges. Finally, the essence is released by a stream of water, then decanted (**Figure 4**). A new mechanical technique based on the bursting of the oleiferous bags under the effect of either a depression or abrasion of the fresh bark would eliminate water and reduce the effects of the essences compounds oxidation [20].
