Investigation and Modeling of Extraction Parameters of Ruta chalepensis L. Essential Oil Jamel Mejri 1 *, Manef Abderrabba 1 , Mondher Mejri 2 1 Unité de recherche en physico-chimie moléculaire, Institut Préparatoire des Etudes Scientifiques et Techniques, IPEST, BP51, La Marsa 2070, Tunisia 2 Département de Génie des Procédés, Institut Supérieur des Etudes Technologiques de Zaghouan, 1121 Mograne, Tunisia Abstract: To evaluate the effects of hydrodistillation parameters and the vegetative cycle of the plant (Ruta chalepensis L.) on the global essential oil yield the response surface methodology was used. The parameters tested are the volume of water in the suspension to be distilled and the time of distillation. The third parameter is the vegetative cycle of the plant. The responses were the global extraction yield and the extraction yield of following essential oil compounds: 2-undecanone, 2-decanone, 2-dodecanone and 2- tridecanone. The optimal conditions selected for the total output of the extraction obtained from the analysis of the response surfaces are: time of distillation: 120 minutes; volume of water in the suspension to be distilled: 500 ml; stage of vegetation: January (young growths). The results show that the time of distillation and the stage of vegetation are the parameters more meaning on the global essential oil yield. Key words: Ruta chalepensis L.; Extraction; Hydrodistillation; Essential oil; Response Surface Methology. Introduction An essential oil is a volatile mixture of organic compounds derived from odorous plant material by physical means 5 . Essential oils are very known by their biological properties and activities in various fields such as the agroalimentary, pharmacy and phytotherapy. They are natural antioxydants: they can be an alternative source of compounds able to protect the lipids in food. Indeed, there is an important interest for the use of antioxydants in food industry, not only like method of safeguarding but also for their beneficial effects on human health 4,6,18,22 . Many studies showed that the essential oils of some plants can be used as inhibitors of the reactions of oxidation of the lipids and the proteins 7 . Essential oils are also used as antibacterial and antifungal activities 14,21,23 . However, these properties may change under the action of certain parameters such as drying, extraction method and stage of vegetation. Drying and drying methods affect yield and essential oils on the chemical composition. The physical properties and antioxidant activity are also affected by drying methods 2,13,17 . The effects of the distillation methods and stage of vegetation were also studied in Satureja hortensis; the highest yield of essential oil was Journal of Essential Oil Bearing Plants ISSN Print: 0972-060X Online: 0976-5026 www.jeobp.com *Corresponding author (Jamel Mejri) E-mail: < jmejri2001@yahoo.fr > © 2012, Har Krishan Bhalla & Sons