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Microwave steam diffusion (MSD) was developed as a cleaner and new process design and operation for isolation of essentials oils and was compared to conventional steam diffusion (SD). The essential oils extracted by MSD for 3 min were quantitatively (yield) and qualitatively (aromatic profile) similar to those obtained by conventional steam diffusion for 20 min. In addition, an optimal operating steam flow rate of 25 g min(-1) and microwave power 200 W were found to ensure complete extraction yield with reduced extraction time. To confirm the efficiency of this process a mathematical model was proposed to describe the mass transfer of essential oil from lavender. Solid-steam mass transfer coefficients obtained by MSD were six times higher than obtained by SD. Scanning electronic microscopy was used to confirm the extraction mechanism of the essential oil present in the glandular trichomes of the flowers from lavender outer surface. MSD was better than SD in terms of energy saving, cleanliness and reduced waste water.

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The present study aims to compare two innovative extraction techniques: microwave assisted hydrodistillation (MAHD) and solvent free microwave extraction (SFME) through traditional extraction techniques: hydrodistillation (HD) and steam distillation (SD) for their efficiency in the extraction of the volatile compounds from Tunisian Thymus vulgaris leaves; the kinetic, yield, composition, and antibacterial activities of the essential oil were assessed in vitro. Resultsshow that the essential oils extracted by microwaves were quantitatively (yield) similar to those obtained through the conventional methods, but qualitatively, essential oils analyzed by GC-MS presented 17, 11, 11, and 8 compounds obtained through SFME, MAHD, SD, and HD, respectively, mostly consisting of carvacrol (89.24-41.17%), followed by γ-terpinene (11.37-1.37%) and para-cymene (27.95-2.05%). The essential oils were screened for antibacterial activity against 5 microorganisms. All essential oils obtained by studied extraction methods Downloaded by [University of Lethbridge] at 05:55 22 June 2016A c c e p t e d M a n u s c r i p t 2 showed the same resistance against Gram (-) and Gram (+) bacteria. The SFME method gave the best results: rapid kinetic of extraction (30 min vs. 35 min for MAHD, 120 min for SD, and 180 min for HD), less energy saving and cleanest process.

Olive oil with rosemary leaves by microwave assisted infusion (MAI) as an alternative to conventional infusion (CI) was evaluated. Microwave heating was applied to the mixture in order to accelerate diffusion of the rosemary volatile compounds into the olive oil. The volatile components of the aromatized oils were quantified by HS‐SPME/GC–MS, as well as several quality indexes such as free fatty acids (FFA), peroxide value (PV), specific coefficients of extinction, chlorophyll and carotenoid content, and color assessment. Fatty acid profiles of the oils aromatized by MAI were compared to those produced by CI. Results showed that the infusion time is reduced from 12 h to 10 min when utilizing MAI in place of CI. MAI treatment caused a slight increase in FFA levels, and specific extinction coefficient indices (K232 and K270). PV during MAI remained unchanged for the first 3 min, after which there was an observable increase. All physico‐chemical values were found to be well below the maximum permitted limits. The MAI treatment reduced chlorophyll and carotenoid levels during the final step of aromatization, thus affecting final color. The MAI aromatized oil was characterized by its clear green color (L*, a*, b* parameters). Fatty acid analysis showed that MAI slightly changed the fatty acid composition of the olive oil. This study indicates that MAI appears to be a viable and rapid method to flavor olive oil with rosemary leaves.

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Microwave-assisted maceration (MAM) was developed as a new and rapid application to flavor the olive oil with dried Rosmarinus officinalis L. leaves. MAM was compared to conventional method (CM) in terms of rapidity of maceration, yield and sensory characteristic of flavored olive oils. Scanning electron microscopy (SEM) sheds light on the physical action of the both maceration methods. 1,8cineole and camphor were two major volatile compounds of rosemary essential oil identified by GC/MS, they were used as keys estimating the level of maceration. The flavored olive oil obtained by MAM for 400 W and 10 min was quantitatively (yield) better than those obtained by CM for 12 h. The SEM showed clearly that the cells were broken and damaged more quickly in MAM than in CM. The MAM was proposed as an efficient, simple and fast application for direct maceration of olive oil with rosemary leaves. PRACTICAL APPLICATIONSFlavoring the olive oil with aromatic plants has been an increasing topic in the food industry, because it provided a new concept by adding value to the olive oil, at the same time, satisfy the sensory requirements of the consumer. Recently, much attention has been given to the application of the microwave energy in several industrial processes. Therefore, the objective of this study was to flavor the olive oil with rosemary leaves using the microwave-assisted maceration (MAM) to enhance the speed of maceration compared to the conventional method. The appropriate comparisons in terms of maceration kinetic, yield and sensory characteristic of flavored oils were determined and the results were discussed.