Sepideh Rashidi - Department of Polymer and Chemical Engineering, South Tehran Branch, Islamic Azad University, Tehran ,Iran
Mohammad Hasan Eikani - Department of Chemical Technologies, Iranian Research Organization for Science and Technology (IROST), Tehran, Iran
Mehdi Arjmand - Department of Polymer and Chemical Engineering, South Tehran Branch, Islamic Azad University, Tehran ,Iran

Instant auto-vaporization method is considered as one of the improved green technologies in the extraction of food components to minimize both the use of organic solvents and the time of extraction. It is a cleaner method compared to other conventional extraction ones. It was used as a thermo-mechanical treatment, exposing the herb to a high-pressure saturated steam for a short-time period, followed by an abrupt pressure drop into a vacuum, which instantly provokes auto-vaporization of volatile compounds and modifications of structure. Thus, the adiabatically vaporization leads to the ultra-rapid cooling of residual herbs, precluding any thermal degradation. An immediate condensation produces a micro-emulsion of water and essential oil. Extraction of essential oil of Hyssopus officinalis L. was studied using multi-cycle instant auto-vaporization process. Separation and identification of the components were carried out by the GC-MS and GC-FID. A comparative study was also performed with other innovative and conventional methods, like UAE, hydrodistillation and Soxhlet. The extraction yield was represented as the ratio of sum of area percentages of all components to area percentage of internal standard (AR/IS). Auto-vaporization at heating time of 100 sec, pressure of 1 bar, 12 cycles, ethanol volumetric percentage of 20% in steam generator feed and mean particles size of 1 mm were found to be able to extract 33.75 (AR/IS) of essential oil presents in the hyssop aerial parts during 20 min. In comparison, the UAE, hydrodistillation and Soxhlet showed the extraction yield of 1.28, 10.27 and 7.90 (AR/IS) for 30 min, 3.5 h and 9 h, respectively.

Hyssopus officinalis L., Essential oil, Instant Auto-vaporization, Hydrodistillation, Ultrasound Assisted Extraction, Soxhlet Extraction