Development of a green innovative semi-industrial scale pilot combined microwave heating and centrifugal force to extract essential oils and phenolic compounds from orange peels

A new process for extraction of essential oils from orange peels (Citrus sinensis L.) using microwave and centrifugal (MW/C) force was studied. MW/C is a combination of microwave heating to explode the internal cells of biological material, and centrifugation to intensify diffusion, collection and separation of compounds of interest. MW/C is performed at atmospheric pressure with an injection of water vapor. A detailed study concerning optimization of different operating parameters like microwave power density and centrifugation was performed. MW/C has been compared to the hydrodistillation method. In addition of essential oils collection, in the aqueous phase several phenolic compounds can be obtained and valorized. Influence of the two main parameters was discussed first on essential oils and, in second part, on phenolic compounds recovery. The new combined MW/C process provided reduction in the extraction time compared to hydrodistillation method, with an advantage to collect in a same experiment volatile and nonvolatile compounds with high quality. Industrial relevance: This work was carried out thanks to the investment of IFTS France, an international technical center worldwide known in the field of solid-fluid separations. Considering the huge amount of plant extracts this new combined system using microwave and centrifugal (MW/C) force may be suitable for scaling up. The results of this investigation on pilot reactors pave the way for the design of an industrial device.