Vegetable microwave-assisted

In order to accelerate sample preparation, new extraction methodologies such as accelerated solvent extraction (ASE) and MAE, based on the use of elevated temperature and pressure to heat the mixture sample-solvent, have been recently developed and applied for PAH extraction from meat [695] and vegetables [696-698]. Garda Falcon et al. [699] used microwave treatment with hexane to accelerate PAH extraction from freeze-dried foods. The fat extracted in this way underwent microwave assisted saponification with ethanolic KOH. Hernandez-Borges et al. [700] combined microwave-assisted hydrolysis and extraction to isolate organic pollutants from mussels, while... 

Barriada-Pereira, M., M.J. Gonzalez-Castro, S. Muniategui-Lorenzo, et al. 2007. Comparison of pressurized liquid extraction and microwave assisted extraction for the determination of organochlorine pesticides in vegetables. Talanta 71 1345-1351. 

This laboratory experiment describes the preparation of a vegetation sample (e.g., grass) for radiochemical analysis. The sample is dried and ashed. In Part 12A, the ash is fused with sodium hydroxide and sodium carbonate to bring it into solution. An alternative method in Part 12B uses a microwave-assisted digestion technique with nitric and hydrofluoric acid. The prepared sample is suitable for radionuclide analysis, notably for radio-strontium or plutonium. 

Microwave-assisted desorption coupled to in situ headspace solid-phase microextraction (HS-SPME) was first proposed as a possible alternative pretreatment of samples collected from workplace monitoring. Therefore, pretreatment that takes a short time and uses little or no organic solvents has led to the recent development of a new extraction technique. Solid-phase micro-extraction (SPME) coupled with GC analysis has been used successfully to analyze pollutants in environmental matrices. MHS has been developed to achieve one-step, in situ headspace sampling of semivolatile organic compounds in aqueous samples, vegetables, and soil [7, 55-58]. 

Osmotic pretreatment before microwave-assisted air drying increase the final overall quality of the product [187]. Fruits and vegetables treated by osmosis can be further dehydrated in a convection dryer to lower the water activity to the level of 0.65-0.90. At those water activities, water content in the material is still high and the product presents such organoleptic attributes as chewiness, softness, elasticity, and plasticity [76,188-190], The product has a natural color, well-preserved flavor, and high retention of vitamins [132], Its shrinkage is much smaller when compared with that observed in convection-dried products at the same water activity. 

Ultrasound-assisted extraction and microwave-assisted extraction have also been employed as complementary techniques in the extraction of vegetable oils. Compared with conventional methods, extraction times are reduced up to ten-fold and yields are increased by 50-500%. 

Spectroscopic, luminescence, turbidimetric, and electrochemical methods of detection have been combined with SIA for the successful determination of amino acids, sugars, and trace elements in matrices such as meats, vegetables, breads, wines, juices, and milks. Many of these methodologies required sample pretreatment and whilst most performed this in an offline manner there have been some reports of online sample cleanup. Microwave assisted digestion was performed in-line for the determination of phosphorous, calcium, magnesium, and iron in slurried foodstuffs, wine, milk, and soft drinks whilst gaseous diffusion allowed interference removal for the determination of urea in milk. 

Most of the extraction techniques of phenolic compounds from vegetables are based on ultrasound-assisted extraction (UAE) [27,44,45], In addition, other techniques have been successfully applied to the pretreatment of phenolic compounds in fruits and vegetables, including pressurized liquid extraction (PLE) [46], solid-phase extraction (SPE) [47], supercritical fluid extraction (SFE) [48], microwave-assisted extraction (MAE) [49], rotary shaker-assisted extraction (RAE), [50] and QuEChERS (acronym of quick, easy, cheap, effective, rugged and safe) [51], as can be observed in Tables 16.3 and 16.4. In some cases, an acid treatment [52] was applied to hydrolyze the glycosides in order to determine the content of free and conjugated flavonoids as aglycons. 

Zhang, M., Jiang, H., Lim, R. X., 2010. Recent developments in microwave-assisted drying of vegetables, fruits, and aquatic products Drying kinetics and quality considerations. Drying Technol. 28(11) 1307-1316. 

Morales-Rubio A, Salvador A, de al Guardia M. 1992. Microwave muffle furnace assisted decomposition of vegetable samples for flame atomic spectrometric determination of calcium, magnesium, potassium, iron, manganese and zinc. Fresenius Journal of Analytical Chemistry 342(4-5) 452 56. 

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