Effect of the main processing parameters of the instantaneous controlled pressure drop process on oil isolation from rosemary leaves. Kinetics aspects

Experiments to isolate the essential oil from rosemary (Rosmarinus officina lis L.) were carried out using a new extraction process: "Detente Instantan ee Controlee" (D.I.C) or "Controlled Instantaneous Pressure drop." This pro cess involves subjecting the rosemary leaves for a short period of time to a steam pressure, followed by an instantaneous pressure drop to a vacuum (a bout 15 mbar). This paper aims to assess the effect of processing pressure, processing time and initial moisture content of leaves before D.I.C. treat ment on the extraction efficiency. The processing pressure varied from 0.5 to 5 bar, the processing time from 1 to 21 minutes and initial moisture con tent from 0.1 to 0.4 g H2O/g dm. It appears that a pressure of about 1 bar, and a treatment time less than 10 minutes are sufficient to extract more t han 97% of the essential oil. The moisture content was not a critical param eter for the isolation efficiency. A stable yield and composition of the oi l was obtained whatever the value of this parameter. The oil was also studi ed by quantitative and qualitative chemical analysis, the effect of modifyi ng the operating conditions on the isolation of 10 components of the rosema ry oil namely alpha-pinene, camphene, beta-pinene, 1,8-cineole, camphor, bo rneol, terpinen-4-ol, alpha-terpineol, bornyl acetate and beta-caryophyllen e.