The essential oil of Algerian Nigella sativa seeds, isolated by microwave steam distillation (MSD) with cryogenic grinding of plant material (CG) were analysed by GC and GC-MS. Two procedures have been investigated, the MSD1 (seeds inside of oven apparatus) and MSD2 (seeds outside of oven apparatus). According to the data values reported in this study the effect of cryogrinding and the technique used on the chemical composition of the essential oils is very important. Monoterpene hydrocarbons (51.2-60.2%) were the main group of CG essential oils compared to CLG (classical grinding) essential oils (33.1-47.8 %). Whereas, the ketones formed the main proportion in CLG essential oils (46.1-59.9 %) followed by CG essential oils (32.7-40.8 %). Forty-nine compounds were identified and significant differences in quantities of the major constituents were observed, mainly were thymoquinone (CLG: 42.3-56.1 % and CG: 28.1-36.0 % ), p-cymene (CLG: 23.1-31.5 %, CG: 33.0- 38.0 %), dehydro-sabina ketone (CLG: 3.1- 3.3 %, GC: 4.4-4.5 %), carvacrol (CLG: 1.3-1.4 %, CG: 0.4-1.1 % ) and longifolene (CLG: 1.5-2.1 %, CG:1.3-1.7 % respectively). On the other hand, the N. sativa essential oil was investigated for its antioxidant activities using four different tests then compared with BHT. Results showed that it exhibit a good activity in each antioxidant system with a special attention for β-carotene bleaching test (IC50: 19 to 28 µg/ml) and reducing power (EC50: 8 to 15 µg/ml).

In this present study, we evaluated composition, antimicrobial and antioxidant activity of clove essential oil. Volatile oils of Eugenia caryophyllata were isolated from cloves after cryogrinding by three methods, conventional hydrodistillation (HD), microwave assisted extraction (MAE) and microwave steam distillation (MSD). The results show that the MAE and MSD techniques constitutes the adequate technique for the extraction operations for the yields and the high content in major component and allows minimizing the energy consumption, the heating time and the formation of artefact products. The proposed methods provide more valuable essential oils with high percentage in eugenol what allows to obtain more biologically active essential oils. The MAE and MSD are green technique since reduce environmental burden (less CO₂ in the atmosphere). Essential oils from Eugenia caryophyllata were subjected to in vitro antibacterial assay against human pathogenic Escherichia coli, Klelsiella pneumoniae, Enterobacter cloacae, Staphylococcus aureus, Bacillus subtilis, Candida albicans, Fusarium culmorum, and Aspergillus carbonarius using disc diffusion method. The antioxidant properties (2,2-diphenyl-picryl-hydrazyl radical (DPPH)) of essential oil and pure eugenol isolated were examined.

Hydrodistillation assisted by microwave (HDAM) and steam distillation assisted by microwave (SDAM) of Curcuma longa L. rhizome (CL) and Carum carvi fruits (CC) were investigated. The effect of the cryogrinding (CG) showed differences in yields and composition of volatile oils compared with classical grinding. HDAM–CG (CL: 1.20%, CC: 1.25%) and SDAM–CG (CL: 1.45%, CC: 1.75%) allowed extraction of substantial amounts of volatile oils in less time compared with HDAM (CL: 0.6%, CC: 1.00%) and SDAM (CL: 0.90%, CC: 1.00%). In addition, the major amounts of volatile oils were globally obtained during the first 5 and 10 minutes of extraction for CL and CC, respectively. A kinetic study of essential oils extraction from CL and CC was quantitatively performed. The composition of the major components and family classes present a significant variation with the extraction time. Essential oils extracted by these two methods were quantitatively (yield) and qualitatively [aromatic profile by gas chromatography (GC) and GC–mass spectrometry (GC–MS)] analyzed. There were differences, especially in the major compounds ar-turmerone (HDAM: 46.00–57.96%, HDAM–CG: 30.85–60.32%) and β-turmerone (HDAM: 14.43–16.74%, HDAM–CG: 10.46–15.77%) for CL, and limonene (HDAM: 23.61–56.97%, HDAM–CG: 38.04–43.00%) and carvone (HDAM: 36.19–64.54%, CC–CG: 53.65–56.31%) for CC.