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A comparative study of traditional simultaneous distillation extraction (SDE), microwave assisted hydrodistillation extraction (MWHD) and ultrasound-assisted extraction (USE) is presented, for the extraction of essential oils from fresh garlic (Allium sativum) cloves. Each method is evaluated in terms of qualitative and quantitative composition of the isolated essential oil. The highly reactive sulfur molecules of the garlic volatile fraction show variable response to the different isolation methods. The application of ultrasound for the extraction of the essential oil is considered to cause a lesser damage of thermal-sensitive molecules, thus, providing a better approach of the compounds primarily responsible for the characteristic odor and taste of freshly chopped garlic. All heat-involving isolation procedures have been shown to differentiate the volatile-fraction profile as analyzed by GC-MS. Especially when grouping the compounds into cyclic and acyclic, the percentage concentrations drop from 77.4% to 8.7% for the acyclic while that of the cyclic compounds increase from 4.7% to 70.8%. The observed fact may be attributed to the effect of the heat applied, which changes from harsh thermal treatment (SDE) to short time thermal (MWHD) and room-temperature isolation (USE). The use of USE proves to be crucial in order to provide reliable insight into garlic's chemistry.

A new methodology for identification of pollen was developed based on FT-IR spectroscopy. Pollen samples of twenty different plant species were collected and the diffuse reflectance infrared Fourier transform (DRIFTS) and KBr pellet spectra were recorded. Libraries of spectra were created. Spectra of unknown plant origin pollen were recorded and compared with those of the corresponding pollen library and the match value was measured automatically using the appropriate software (OMINC ver. 3.1). From the same pollen samples, microscopic slides were prepared and the photographs of the pollen grains were used as a second comparison method. Using light microscopy, the pollen identification is usually limited to the family or generic name, while FT-IR spectroscopy can distinguish species belonging to the same genus. This method is simple and fast, and when the DRIFTS technique is used the sample is not destroyed.

A novel application of ultrasounds is presented for the improvement of the efficiency of the production of FAME (or biodiesel) from materials not used so far for this purpose, such as seed cakes. The novelty of this work is the introduction of in situ derivatization assisted by ultrasounds (ultrasonically assisted extraction transesterification) for biodiesel production. Thus, the TG contained in solid material are extracted and immediately transesterified in a methanolic solution of 1 M NaOH in an ultrasonic field. The total yield of FAME from seeds that contain TG is greatly increased in most instances. In the seeds used in this work, yields were increased from 46 to 85.5 % for cotton, 67.2 to 93 % for sunflower, and 43.2 to 83.5 % for sesame. An FTIR methodology was developed to determine the percentage of FAME in the n-hexane layer of the reaction and thus, to monitor the reaction process. Overall advantages of the proposed methodology include the elimination of saponification, low reaction time, milder reaction conditions, and higher FAME yields.

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