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Response surface methodology (RSM) was used to evaluate the processing parameters’ effects of three extraction processes namely: steam-distillation (SD), steam-diffusion (SDiff) and hydro-distillation (HD) on the extraction of thyme essential oil. The tested parameters are the mass of vegetable, the extraction time and the water vapour flow; the response is the essential oil yield. According to the method of statistics, a second order polynomial function was assumed to approximate the extraction yield of the essential oil. The models’ matching test, estimated by the determinant coefficient R2 (93.42 % for SD, 80.46 % for SDiff and 94.73 % for HD), revealed a quite matching between experimental and predictive values. When compared, the effectiveness of the three processes according to the extraction duration showed that SD and SDiff are the most powerful with a value that exceeds 80 % time wise. Analysis highlighted that the oils were characterised by a high amount of oxygenated monoterpenes and c...

Analysis of the essential oil of Origanum glandulosum (Desf.) from Algeria, by GC and GC-MS made it possible to identify 33 components, representing 92.7 % of the oil. The major components were thymol (38.8 %) followed by carvacrol (32.9 %), p-cymene (7.9 %) and γ-terpinene (5.1 %).

International audience; This chapter presents a complete picture of current knowledge on useful and green bio-solvent “terpenes” obtained from aromatic plants and spices through a steam distillation procedure followed by a deterpenation process. Terpenes could be a successful substitute for petroleum solvents, such as dichloromethane, toluene, or hexane, for the extraction of natural products. This chapter provides the necessary theoretical background and some details about extraction using terpenes, the techniques, the mechanism, some applications, and environmental impacts. The main benefits are decreases in extraction times, the amount of energy used, solvents recycled, and CO2 emissions.

International audience; A microwave steam distillation (MSD) of essential oils from fresh citrus by-products (orange peels) was studied. The effectiveness of this innovative method in extraction of citrus essential oils have been evaluated and compared to conventional steam distillation. MSD offers important advantages like shorter extraction time (6 min), cleaner features and provides an essential oil with better sensory properties (better reproduction of natural fresh fruit aroma of the citrus essential oil) at optimized power (500 W). Results from chemical and cytological approaches confirm the effectiveness of this new technique, that allows substantial savings in terms of time and energy. Industrial relevance: The treatment of by-products represents a strong demand for industrial fruits processing, which produces tonnages of waste material such as peels, seeds and fibers. The disposal of these materials usually represents an industrial legal restriction problem. Moreover, the waste treatment represents significant costs and is often misjudged by companies. Transformation of waste products with high value-added allows companies to reduce the global treatment costs, sometimes even to take some profits and thus improve their competitiveness. Moreover, the recovery process of by-products is part of the current existing sustainable development and environmental protection.

International audience; Steam distillation (SD) is routinely used by analysts for the isolation of essential oils from herbs, flowers and spices prior to gas chromatographic analysis. In this work, a new process design and operation for an improved microwave steam distillation (MSD) of essential oils from aromatic natural products was developed. To demonstrate its feasibility, MSD was compared with the conventional technique, SD, for the analysis of volatile compounds from dry lavender flowers (Lavandula angustifolia Mill., Lamiaceae). Essential oils isolated by MSD were quantitatively (yield) and qualitatively (aromatic profile) similar to those obtained by SD, but MSD was better than SD in terms of rapidity (6 min versus 30 min for lavender flowers), thereby allowing substantial savings of costs in terms of time and energy. Lavender flowers treated by MSD and SD were observed by scanning electron microscopy. Micrographs provide evidence of more rapid opening of essential oil glands treated by MSD, in contrast to conventional SD

International audience; Essential oils of thyme (Thymus numidicus (Poiret)) from Algeria were isolated by steam distillation, analysed by gas chromatography coupled with the mass spectrometry (GC-MS) and investigated for their insecticidal activities against Rhizopertha dominica. Contact toxicity of global oil recovered after one hour of extraction and its fraction F1 recovered after 2.5 minutes of extraction were tested using the filter paper method. Analysis of the essential oil made it possible to identify 14 components, representing 75.4 % of the oil. The major components were thymol (51.0 %) followed by carvacrol (9.4 %), linalool (3.3 %), thymol-methyl-ether (3.2 %) and iso-caryophyllene (2.7 %). The evolution of the yield and the composition of essential oil as function of time extraction show that steam distillation is a very rapid process and the duration of extraction could be limited to15 minutes, since more than 94 % of oil are extracted. The toxicity tests show that thyme oil and its fraction F1 have an insecticidal activity, nevertheless, the mortality obtained for global oil are weaker compared with those obtained for the F1 fraction. This toxicity would be allotted to the presence instrong proportion of linalool and thymol.

International audience; In this study, extraction of essential oil, polyphenols and pectin from orange peel has been optimized using microwave and ultrasound technology without adding any solvent but only ‘‘in situ’’ water which was recycled and used as solvent. The essential oil extraction performed by Microwave Hydrodiffusion and Gravity (MHG) was optimized and compared to steam distillation extraction (SD). No significant changes in yield were noticed: 4.22 ± 0.03% and 4.16 ± 0.05% for MHG and SD, respectively. After extraction of essential oil, residual water of plant obtained after MHG extraction was used as solvent for polyphenols and pectin extraction from MHG residues. Polyphenols extraction was performed by ultrasoundassisted extraction (UAE) and conventional extraction (CE). Response surface methodology (RSM) using central composite designs (CCD) approach was launched to investigate the influence of process variables on the ultrasound-assisted extraction (UAE). The statistical analysis revealed that the optimized conditions of ultrasound power and temperature were 0.956 W/cm2 and 59.83°C giving a polyphenol yield of 50.02 mg GA/100 g dm. Compared with the conventional extraction (CE), the UAE gave an increase of 30% in TPC yield. Pectin was extracted by conventional and microwave assisted extraction. This technique gives a maximal yield of 24.2% for microwave power of 500Win only 3 min whereas conventional extraction gives 18.32% in 120 min. Combination of microwave, ultrasound and the recycled ‘‘in situ’’ water of citrus peels allow us to obtain high added values compounds in shorter time and managed to make a closed loop using only natural resources provided by the plant which makes the whole process intensified in term of time and energy saving, cleanliness and reduced waste water.