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Novel Applications of Microwave Techniques in the Food and Environmental Industries
29-34Views:90During the microwave processing, despite the conventional heating, the material heats consistently inside. This property of microwave is utilized by drying and dehydration processes. The thermal sensitivity of raw materials of food industry requires development of gentle, fast and controllable technologies, which is realizable by means of combination of conventional and microwave techniques. The other important application area of the microwave technique is food industrial practice is enhancing the microbial safety of products, mainly by pasteurization processes. In recent time the strict environmental regulation necessitate developing more effective treatment of wastes, waste waters and sewage sludge. Because a part of these techniques are heat and power demanded, the microwave technique may be an alternative process in execution of sludge conditioning, drying or gasification and pyrolysis.
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Comparative analysis of sample preparation methods to determine the concentration of arsenic in soil- and plant-samples
167-170Views:130Arsenic contamination of the fields and groundwater is a global problem. Alföld is the most affected area in Hungary. Irrigation witharsenic contaminated water, and crop production on the contaminated soil can cause a food safety problem, because arsenic is easy taken up by the cell of the plant roots. To prevent this, very important to monitoring the arsenic content of soils and plants. Inductively coupled plasma mass spectrometry (ICP-MS) is a fast, easy method to determined the concentration of minerals in the case of plant and soil samples The analytical methods can give reliable, results if the analytical process, including the sample preparation method, is the best. The objective of this study was to compare 3 type of sample preparation method which was dry ashing, wet digestion in open system, and microwave digestion. As a result of our experiement shows the microwave digestion is the appropriate method to determined the arsenic content of soil samples. In the case of plant samples we can use wet digestion in open system or microwave digestion as a samle preparation method.
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Physical and chemical treatment of poultry feather from the slaughter-house
51-56Views:65The 15-20% of the by-products of meat – and poultry industry – that unsuitable for human consumption – contains keratin. The slaughter technology of poultry produces large amount of poultry feather with 50-70% moisture content. This means more million tons annually worldwide (Williams et al., 1991; Hegedűs et al., 1998). The keratin content of feather can be difficulty digested, so physical, chemical and/or biological pretreatment is needed in practice, which has to be set according to the utilization method.
Our applied treatments were based on biogas production, which is a possible utilization method. In the IFA (TULLN) Environmental Biotechnology Institute the feather was homogenized, and – according to the previous examinations – the most effective 1:2 feather-distilled water ratio or 1% NaOH-solution was used, and then treated with microwave (70, 130, 160 °C) during 1 hour time period. DM% and oDM% content was analyzed in the original samples, and the pH, Carbon-, Nitrogen-content in the output, too. Based on the received correlation coefficients (R) and related significance values (Sig.) I concluded, that the C-, N-content and the pH values weren’t influenced by any of the additives. The temperature
affected all three tested factors. The temperature showed a strong coherency with the N-content and the pH value when distilled water was used and weak-medium coherency with the Carboncontent. With NaOH-solution treatment the temperature gave strong coherency with the C- and N-content, as well as medium coherency with the pH. Our objective was to determine the method with effectively the pre-treating of poultry feather for biogas production or composting and to prepare of the treated samples for N and C analyzing. Our next aims will be the elaboration of the technological parameters of heat pre-treatment and microbial digestion of poultry feather for biogas production. -
Selenium speciation analysis of selenium-enriched food sprouts
23-28Views:183In this present study, we prepared selenium-enriched pea and wheat sprouts. During our research we aimed not only to measure the total selenium content of the sprouts but to identify different selenium species.
Scientifical researches show why the analytical examination of different selenium (Se) species is necessary: consumption of all kind of Se-species is useful for a person who suffers in selenium deficit, while there is significant difference between effects of different Se-species on person, in whose body the Se-level is just satisfactory. Biological availability, capitalization, accumulation, toxicity of Se-species are different, but the main difference was manifested in the anti-cancer effect of selenium.
During our research selenium was used in form of sodium selenite and sodium selenate, the concentration of the solutions used for germination was 10 mg dm-3. Control treatment meant germination in distilled water. Total selenium content of sprout samples was measured after microwave digestion by inductively coupled plasma mass spectrometry (ICP-MS). Different extraction solvents were applied during sample preparation in order to separate different Se-species (0.1 M and 0.2 M HCl or 10 mM citric acid buffer). We wanted the following question to be answered: Which extraction solvent resulted the best extraction efficiency? Selenium speciation analysis of sprout sample extracts was performed by high performance liquid chromatography with anion exchange column, detection of selenium species was performed by ICP-MS.
Evaluating our experimental results we have been found that significant amount of selenium of inorganic forms used during germination transformed into organic selenium compounds. There was difference between the amount of Se-species in pea and wheat sprouts and selenium uptake and repartition of selenium species were depended on Se-form used during germination. In addition the chromatogram analysis made us clear as well, that the citric acid solvent proved to be the most effective extraction solvent during sample preparation int he view of organic Se species.
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Comparison of the sample preparation methods worked out for the examination of the element content of wine
77-82Views:113The examination of the potentially toxic elements content of the wines is not easy task, because the most elements are in little concentration (mg kg-1 or μg kg-1) in the wine and the wines contain great amount of organic matrix. The efficient sample preparation is essential for the accurate determination of element content. The eim of our research was to determine which sample preparation method will be the most efficient in examination of wines with ICP technology. The examined wine sample was a 2008 Chardonnay from the Eger wine region. We did the sample preparation and analysis examination in University of Debrecen, Centre for Agricultural and Applied Economic Sciences, Institute of Food Science, Quality Assurance and Microbiology.
We did the analysis examinations with ICP- MS (inductively coupled plasma mass spectroscopy). We always did the sample preparations and the examinations in three times rehearsal. The applied sample preparation methods: dilution with distilled water, open digestion and microwave digestion.
We were able to measure B, Al, Mn, Fe and Zn with only dilution and open sample preparation. In the smaller quantity present Sr and Ba were measurable in the wine in the case of all three methods well. We were able to measure the Co with dilution and open digestion method, while Cr, Ni, and Te with only dilution method. In the case of arsenic we were not able to measure reliable result with dilution and open digestion method because of organic matrix and other components
(alcohols, monosaccharides, polysaccharides, polyalcohols and inorganic salts). On the whole we are able to say that in the case of certain elements (B, Mn, Fe, Zn, Sr, Ba) the open digestion and dilution sample preparation is applicable well, however, in the case of certain elements (As, Al, V, Cr, Se, Mo, Cd, Hg, Pb) we have to develop the methods. It may be development of one of the way, if we develop sample preparation methods to examined element specifically and not
to wine generally. -
Relation of availability and barley uptake of some potentially toxic elements
7-10Views:70A small-plot microelement load field trial was set up on brown forest clay soil with eight elements (Al, As, Cd, Cr, Cu, Hg, Pb, Zn), on 3 levels each (0/30, 90, 270 kg element ha-1). The soil was treated with soluble salts of elements once at initiation (1994). In the seventh year of the experiment (2001) winter barley was the test plant. The total element content was determined in plant samples (shoot, straw, grain) after microwave digestion using cc.HNO3+cc.H2O2. The element composition of the prepared samples was determined using ICP-MS technique. In the experiment toxic effects of treatments and yield loss could not be observed. Zn and As contents in barely shoots were only moderately increased by increasing microelement loads. Effects of Cr, Cu, Hg, Pb and Al treatments could not be observed. On the other hand, Cd accumulation was significant in the shoot. Cd content was also increased both in straw and grain. Results of this experiment prove that Cd remains mobile in the soil-plant system for a long time. Its accumulation can be observed both in vegetative and reproductive parts of plants without toxic symptoms and yield loss.
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Essential oil extraction from herbs and their use in the food industry
59-74Views:343Essential oil extraction of wild caraway and thyme was performed using a classical (HD) and microwave hydro-distillation (MWHD) and a laboratory supercritical fluid extraction (SFE) with a carbon dioxide as solvent. Our experiments demonstrated that the extraction yield of the essential oil performed in same conditions was influenced by the location of growth area; the maximum extraction yield of 10 ml 100 g-1 caraway was obtained from dried seeds collected from Csíkmadaras. This quantity far exceeded the yield of the Újtusnád samples. In the case of wild caraway (Carum carvi L.), the extraction method influenced thecomposition of the essential oil (carvone/limonene ratio), the highest limonene content being achieved by classical hydro-distillation. In the case of thyme, this effect was not detected, the thymol/carvacrol ratio was independent from the given extraction method. The obtained thyme essential oil possesses high antimicrobial activity demonstrated by agar diffusion test. The thyme extract provides a good protection against microorganisms collected on the surface of fresh vegetables following bacterial stains: Citrobacter portucalensis, Pseudomonas hunanensis, Pseudomonas baetica, Pseudomonas parafulva, Bacillus mojavensis and Enterobacter cloacae. Protective effect was also detected on the vegetable surface of by chitosan-based edible film coating during a 6-day-long storage period at a temperature of 4 °C. The caraway essential oil used as soft cheese seasoning with a direct, dilution-free method, proved to be unsuitable because the uneven distribution and confer a strong, unpleasant taste to the product in comparison with the ground wild caraway seed-dressed cheese.