AN ORIGINAL MICROWAVE STEAM DIFFUSION FOR EXTRACTION OF ESSENTIAL OIL FROM ORANGES PEELS – EXPERIMENTAL AND THEORETICAL STUDY

Abstract

A new process design and operation for extraction of essential oils was applied on oranges fresh peels: Microwave Steam Diffusion (MSD). MSD has been compared with conventional steam diffusion (SD). The influence of two operating conditions, the microwave power and the steam flow rate, on the extraction performances were studied. A second-order central composite design (CCD) has been used to investigate the performance of the new device. The response surface methodology (RSM) allowed us to determine optimal conditions for the extraction of orange essential oil: a steam mass flow rate of 25 g/min and 200 W of microwave power were found to give maximum extraction yield and shorter time of extraction. In order to confirm the efficiency of this process a mathematical model was proposed to describe the mass transfer of essential oil from orange peels. Thus, solid-steam mass transfer coefficient obtained by MSD was three times greater than those obtained by SD. This may allow a reduction of the extracting time and a better preservation of essential oils quality. The essential oils extracted by MSD for 12 minutes were quantitatively (yield) and qualitatively (aromatic profile) similar to those obtained by conventional steam diffusion for 40 minutes. Extraction of essential oils from orange peels with MSD was better than SD in terms of energy saving, cleanliness and product quality.