The novel green extraction of essential oil for quality pharmaceutical products

Abstract

Essential oils are secondary metabolites produced by aromatic plants which have various applications in the industries. The conventional method to extract essential oil from plants such as steam distillation, hydro distillation and solvent extraction have many drawbacks that lead to the research on the new technique to overcome the flaws. This research was conducted to introduce a new method to extract essential oils where in this new method, the extraction process has been done in a closed vacuum system without the addition of any solvents or water. The novelty of this method is the closed system extraction process where all the compounds of the essential oil were trapped inside the system to prevent the loss of valuable components. The extraction studies for this solvent free method was conducted for both laboratory scale and pilot scale. For the laboratory scale, extraction process using solvent free method and hydro distillation method was conducted for comparison. The peels from Citrus sinensis and the leaves from Chromolaena odorata, Cymbopogon nardus and Baeckea frutescens have been extracted for their essential oils. The essential oils collected from both methods were measured for their yield and physical characterizations. From the results obtained, it showed that the essential oil yield for all the four plants used was significantly higher by using solvent free method compared to hydro distillation method. The yield for solvent free method has been increased by 100% for Chromolaena odorata, 76% for Cymbopogon nardus, 92% for Baeckea frutescens and 174% for Citrus sinensis. Baeckea frutescens essential oil was selected for further analysis. The morphology image of Baeckea frutescens essential oil glands before and after extraction using both methods were determined using Scanning Electron Microscope (SEM). The essential oil was then being analyzed using Gas Chromatography (GC) and Gas Chromatography - Mass Spectrometry/Mass Spectrometry (GC-MS/MS) for their chemical constituents. As expected from the compound elucidations, solvent free method has more compounds compared to hydro distillation method. One new compound which is 3-carene has been obtained by using solvent free method. The existence of 3-carene in this essential oil was not been reported before. It was also discovered that the compounds obtained from solvent free method contained lighter molecular mass compared to the compounds from hydro distillation method which have mostly heavier molecular mass fractions. This is in alignment with the prediction that the new method can preserve lower boiling point compounds which would have lighter molecular mass. With the convincing results from the laboratory scale, the pilot scale for the solvent free method has been designed and developed. The pilot scale essential oil extractor has a maximum of 30-liter capacity for the plant material. As the new method of extraction were more convenient, less processing steps, zero solvent waste and less time consumptions, hence, it is suitable for industrial application such production of pharmaceutical products as active components in medicines or as fragrance ingredients in aromatherapy and perfumery.