Ricerc@Sapienza

In spite of the growing interest in essential oils (EOs) and their commercial importance, it is not yet clear how development factors influence the plant material optimum harvesting period for EOs production. factors that determine the EOs' composition and yield are numerous, and in some cases, it is quite difficult to isolate them as many are interdependent and influenced by each other. Therefore, EOs chemical composition is subject to high quantitative and qualitative variations, as well as their related biological activities or properties.

Steam distillation is known to be the most prevalent method of essential oil extraction. Despite many studies on extraction methods, there is no report about the impact of distillation process duration on the yield and oil quality. A new 24-h steam distillation process for extraction of plant essential oils is presented. For improving the total yield, prolonged and continued isolation was used. A selection of plant species from Lamiaceae and Apiaceae families was subjected to direct steam distillation and essential oils were collected at different times (1, 2, 3, 6, 12 and 24 h).

Membrane reactors are attracting increasing interest because of the opportunity they represent in increasing the efficiency of small-scale systems. Their use in gas phase reactions has been proposed for a variety of applications, where they may act either as selective extractors or as distributors. In particular, membrane reactors are generally employed for the selective permeation of hydrogen.