Microwave-Assisted Hydro-Distillation of Essential Oil from Rosemary: Comparison with Traditional Distillation.

Original Article Microwave-Assisted Hydro-Distillation of Essential Oil from Rosemary: Comparison with Traditional Distillation Sara Moradi 1*, Alireza Fazlali 1, and Hamid Hamedi 2 1. Department of Chemical Engineering, Arak University, Arak, Iran 2. Department of Chemical Engineering, University of Science and Technology, Tehran, Iran Abstract * Corresponding author: Sara Moradi, M.sc., Department of Chemical Engineering, Arak University, Arak, Iran E-mail: Received: 28 Aug 2016 Accepted: 11 Feb 2017 Background: Hydro-distillation (HD) method is a traditional technique which is used in most industrial companies. Microwave-assisted Hydro-distillation (MAHD) is an advanced HD technique utilizing a microwave oven in the extraction process. Methods: In this research, MAHD of essential oils from the aerial parts (leaves) of rosemary (Rosmarinus officinalis L.) was studied and the results were compared with those of the conventional HD in terms of extraction time, extraction efficiency, chemical composition, quality of the essential oils and cost of the operation. Results: Microwave hydro-distillation was superior in terms of saving energy and extraction time (30 min, compared to 90 min in HD). Chromatography was used for quantity analysis of the essential oils composition. Quality of essential oil improved in MAHD method due to an increase of 17% in oxygenated compounds. Conclusion: Consequently, microwave hydro-distillation can be used as a substitute of traditional hydro-distillation. Avicenna J Med Biotech 2018; 10(1): 22-28 Keywords: Essential Oil, Hydro distillation, Microwave distillation, Rosemary Introduction Rosmarinus officinalis L., commonly known as rosemary, is a woody, perennial herb with fragrant, evergreen, needle-like leaves native to the Mediterranean region. Rosemary’s antioxidant properties are still used to extend the shelf life of prepared foods 1-3. Rosemary is also known medicinally for its powerful antioxidant activity and antibacterial properties 4 and as a chemopreventive agent 5. Today, essential oil of rosemary is widely used in the cosmetic industry producing various bathing essences, hair lotions and shampoos 6. Traditional methods used for extraction of essential oil were Hydro-distillation (HD) or steam distillation. However, the loss of some components and the degradation of some unsaturated compounds by thermal effects 7,8 or by hydrolysis can take place by these conventional extraction techniques. These disadvantages have changed the approach of the recent research and stimulated the intensification, optimization and improvement of existing and novel "green" extraction techniques 9,10. Some of these methods are: UltrasoundAssisted Extraction, Microwave-Assisted Extraction and CO2 supercritical extraction. The supercritical fluid extraction of rosemary with CO2 has been the object of many researches 11 and has become a valid alternative to the more conventional extraction procedures, mainly 22 22 because the dissolving power of the extracting medium can be adjusted by regulating pressure and temperature conditions. However, the high cost of producing specific products has limited its use. In certain cases, the extractive power of supercritical CO2 is insufficient under conventional conditions. Microwave-assisted solvent extraction appeared to be particularly attractive for isolation of essential oil 12,13. Microwave-assisted Hydro-distillation (MAHD) combines rapid heating in the microwave field with the traditional solvent extraction. This significantly enables saving of time, so the extraction can be completed in meter of minutes 14,15. In an attempt to take advantage of microwave heating with the conventional HD, MAHD was developed and used for the extraction of essential oils from Xylopia aromatica (Lamarck) and Lippia alba (Mill) 16,17. Tigrine-Kordjani et al 18 developed a Microwave Assisted Distillation (MAD) with free solvent for laboratory scale applications in the extraction of essential oils from different kinds of aromatic plant. Sui et al 19 have worked on an efficient Microwave Pretreatment (MP) method to maintain quality of postharvest rosemary leaves and observed that MP could be a good method for extracting essential oil and maintaining quality in rosemary and other aromatic herbs. Lucchesi et al 20 had a study on comparing solvent-free micro- Copyright © 2018, Avicenna Journal of Medical Biotechnology. All rights reserved. Vol. 10, No. 1, January-March 2018 Moradi S, et al wave extraction of essential oil from aromatic herbs with conventional hydro-distillation. They found that the SFME method yields an essential oil with higher amounts of more valuable oxygenated compounds, and allows substantial savings of costs, in terms of time, energy and plant material. SFME is a green technology and appears as a good alternative for the extraction of essential oils from aromatic plants. In this paper, the essential oil from rosemary obtained by microwave hydro-distillation has been compared with those obtained by conventional hydrodistillation. Then, the quality and quantity of essential oil, cost, energy consumption and safety environmental consideration of two methods were studied. Also, different parameters on essential oil extraction quantity and quality were checked.The aim of this research was finding an optimum method for extraction of essential oil. Materials and Methods Material Leaves of the cultivated plants of rosemary (Rosmarinus officinalisL.) were collected from Arak and Isfahan Universities. The leaves were dried in shade for two weeks. Hydro-Distillation (HD) apparatus and procedure 100 gr of rosemary leaves were submitted to hydrodistillation with a clevenger-type apparatus with a maximum delivered power of 1000 W. The essential oil was extracted with 300 ml of water in a 2 L flask for 90 min (until no more essential oil was obtained). Then, the essential oil was collected and stored at laboratory condition. Microwave-Assisted Hydro-Distillation (MAHD) apparatus and procedure Microwave hydro-distillation has been performed using the Tecnokit Chen (Italy, Tek-2611) microwave oven (Figure 1). It is a 2450 MHz multimode microwave with a maximum delivered power of 900 W. In a typical MAHD procedure performed at atmospheric pressure, 100 gr of rosemary were heated for 30 min with addition of 300 ml water. This period was sufficient to extract all the essential oils from the sample. Each extraction was performed at least three times. Gas chromatography The essential oils obtained at different conditions were analyzed by gas chromatography. The capillary column used for the analysis was HP-5MS (30 m×0.25 mm×0.25 μm) with a 5% phenyl methyl siloxane stationary phase. The GC analysis was performed with the following conditions: flow rate, 0.4 ml/min; FID temperature, 275°C; make-up gas type, He with a make-up flow rate of 45 ml/min. Identification of the components of the essential oils were done by co (...truncated)