Figure 17. The water-steam distillation method by cohobation for extraction essential oil [114].
There is other type of continuous systems known as continuous systems. In the late 20th century, essential oil producers were forced to load and unload steel after loading and finishing the process regularly. So they set out to create a process that could produce essential oils continuously. In such a way that plant materials are slowly loaded into the upper steel and exit from the bottom. In this method, the whole biomass is in contact with steam and ensures the optimal extraction of essential oil. This method is not suitable for inflorescences, fruits and roots [9].