Solvent free microwave extraction

Lucchesi, M.E., F. Chemat, and J. Smadja. 2004. Solvent-free microwave extraction of essentials oil from aromatic herbs Comparison with conventional hydro-distillation. J. Chromatogr. A 1043 323-327. 

Lucchesi, M.E., Smadja, J., Bradshaw, S., Louw, W. and Chemat, F. (2007) Solvent free microwave extraction of Elletaria cardamomum L. a multivariate study of new technique for the extraction of essential oil. journal of Food Engineering 79, 1 079-1 086. 

Solvent-free microwave extraction (SFME) is a recently developed green technique, performed in atmospheric conditions without adding any solvent or water and being applied to the extraction of essential oil from fresh plant or dried materials. The essential oil is evaporated by the in situ water in the plant materials. Wang et al. 

A relatively simple apparatus was described by Lucchesi et al. (2004) for extracting essential oils from aromatic plant material by atmospheric solvent-free microwave extraction (SFME) without the addition of any solvent or water. The essential oils from spices like star anise extracted by SFME for 30 min and lh were similar to those obtained by conventional hydrodistillation (HD) for (respectively) 4 and 8 h. 

Loupy (France) and Varma (USA) Microwave green chemistry Chemat and Lucchesi (France) Solvent-free microwave extraction... 

Solvent-free Microwave Extraction Concept, Application, and Future... 

Fig. 22.3. Solvent-free microwave extraction Microwave Clevenger .

Solvent-free Microwave Extraction Specific Effects and Proposed Mechanisms... 

Solvent-free microwave extraction and partitioning of aroma compounds may occur by one of these two proposed extraction mechanisms or by a combination ... 

Smadja, Solvent-free microwave extraction of volatile natural substances. American patent, US 2004/0187340A1, 2004. 

P. Mengal, B. Mompon, Method and plant for solvent-free microwave extraction of natural products. Canadian patent, CA 2161127, 1994. 

Another possibility for essential oils extraction is the use of microwave-assisted extraction (MAE). This methodology appeared to be quite attractive for the isolation of essential oils. The main advantage of using MAE for essential oils extraction is the effective heat transfer that allows quicker times of extraction as compared to classical methods. In the last few years, different applications using microwave energy have been developed. A recent modification of this technique is solvent-free microwave extraction (SEME), where the sample is placed in the reactor inside the microwave oven without any solvent.A cooling system outside the micro-wave oven cool the extract continuously. Einally, the mixrnre of water and essential oil is collected and separated in a vessel. 

The first applications of MAE dealt with the extraction of essential oils from plant products was reported in 1994 [45]. Microwave heating was used for the isolation of essential oils. Solvent free microwave extraction (SEME) involves microwave heating involves dry distillation at atmospheric pressure for the isolation of the essential oils in fresh plant materials. SFME was used to obtain essential oils from different spices such as ajowan, cumin, and star anise [46,47], and three different aromatic herbs (basil, garden mint, and thyme) [47]. Using the SFME method, either solvent or water is needed if fresh plant material is used. However, in case of dry plant material, the sample should be rehydrated by soaking in water before the extraction. 

Lucchesi, M.E., Chemat, F., and Smadja, J. 2004. An original solvent free microwave extraction of essential oils from spiees. Flavour and Fragrance Journal, 19, 134-138. 

---