Template-Type: ReDIF-Article 1.0 Author-Name: A. Synytsya Author-Workplace-Name: Department of Carbohydrate Chemistry and Technology, Institute of Chemical Technology, Prague, Czech Republic; 2Institute of Macromolecular Chemistry, Czech Academy of Science, Prague, Czech Republic Author-Name: J. Opíková Author-Workplace-Name: Department of Carbohydrate Chemistry and Technology, Institute of Chemical Technology, Prague, Czech Republic; 2Institute of Macromolecular Chemistry, Czech Academy of Science, Prague, Czech Republic Author-Name: J. Brus Author-Workplace-Name: Department of Carbohydrate Chemistry and Technology, Institute of Chemical Technology, Prague, Czech Republic; 2Institute of Macromolecular Chemistry, Czech Academy of Science, Prague, Czech Republic Title: 13C CP/MAS NMR spectra of pectins: a peak-fitting analysis in the C-6 region Abstract: 13C CP/MAS NMR spectra of pectin samples were measured and interpreted. The influence of methylesterification and O-acetylation on chemical shifts of pectin carbons was studied using model pectate, pectinates, and their acetylated derivatives. The spectra were analysed also by peak fitting in C-6 region to obtain the values of methylation (DM), amidation (DAm) and acetylation (DAc), degrees. The results were in a good agreement with both convenient methods (photometry, elemental analysis) and the NMR method based on the relative areas of OCH3 (DM) and CH3 (DAc) resonances. Keywords: 13C CP/MAS NMR, pectins, peak fitting, degrees of methylation (DM), degrees of acetylation (DAc) Journal: Czech Journal of Food Sciences Pages: 1-12 Volume: 21 Issue: 1 Year: 2003 DOI: 10.17221/3471-CJFS File-URL: http://cjfs.agriculturejournals.cz/doi/10.17221/3471-CJFS.html File-Format: text/html X-File-Ref: http://agriculturejournals.cz/RePEc/caa/references/cjf-200301-0001.txt Handle: RePEc:caa:jnlcjf:v:21:y:2003:i:1:id:3471-CJFS Template-Type: ReDIF-Article 1.0 Author-Name: I. Jordáková Author-Workplace-Name: Department of Food Preservation and Meat Technology and Author-Name: J. Dobiáš Author-Workplace-Name: Department of Food Preservation and Meat Technology and Author-Name: M. Voldich Author-Workplace-Name: Department of Food Preservation and Meat Technology and Author-Name: J. Poustka Author-Workplace-Name: Department of Food Preservation and Meat Technology and Title: Determination of vinyl chloride monomer in food contact materials by solid phase microextraction coupled with gas chromatography/mass spectrometry Abstract: The present study concerns the optimisation of the headspace solid phase microextraction (HS/SPME) combined with gas chromatography/mass spectrometry (GC/MS) for the vinyl chloride monomer determination. Samples of PVC materials were analysed using the Carboxen/Polydimethylsiloxane (CX/PDMS) 75 µm fibre. For this fibre, the achieved limit of detection was 0.05 µg/kg, and that of quantification 0.17 µg/kg, respectively, with RSD 5%. The levels of VCM found ranged from 0.29 to 0.44 mg/kg, in the case of foil, the VCM content determined was 3.65 mg/kg which means that the maximal limit allowed was exceeded. Keywords: migration, solid phase microextraction (SPME), vinyl chloride monomer Journal: Czech Journal of Food Sciences Pages: 13-17 Volume: 21 Issue: 1 Year: 2003 DOI: 10.17221/3472-CJFS File-URL: http://cjfs.agriculturejournals.cz/doi/10.17221/3472-CJFS.html File-Format: text/html X-File-Ref: http://agriculturejournals.cz/RePEc/caa/references/cjf-200301-0002.txt Handle: RePEc:caa:jnlcjf:v:21:y:2003:i:1:id:3472-CJFS Template-Type: ReDIF-Article 1.0 Author-Name: Jan Pokorný Author-Workplace-Name: Department of Food Chemistry and Analysis, Institute of Chemical Technology, Prague, Czech Republic Author-Name: Lucie Parkányiová Author-Workplace-Name: Department of Food Chemistry and Analysis, Institute of Chemical Technology, Prague, Czech Republic Author-Name: Zuzana Réblová Author-Workplace-Name: Department of Food Chemistry and Analysis, Institute of Chemical Technology, Prague, Czech Republic Author-Name: Ludmila Trojáková Author-Workplace-Name: Department of Food Chemistry and Analysis, Institute of Chemical Technology, Prague, Czech Republic Author-Name: Hidetoschi Sakurai Author-Workplace-Name: Department of Agriculture and Biological Chemistry, College of Bioresource Sciences, Nihon University, Kanagawa, Japan Author-Name: Tatsuo Uematsu Author-Workplace-Name: Department of Agriculture and Biological Chemistry, College of Bioresource Sciences, Nihon University, Kanagawa, Japan Author-Name: Mitsuyoshi Miyahara Author-Workplace-Name: Department of Agriculture and Biological Chemistry, College of Bioresource Sciences, Nihon University, Kanagawa, Japan Author-Name: Tomohiro Yano Author-Workplace-Name: Department of Agriculture and Biological Chemistry, College of Bioresource Sciences, Nihon University, Kanagawa, Japan Title: Changes on Storage of Peanut Oils Containing High Levels of Tocopherols and β-Carotene Abstract: We compared changes of tocopherols and b-carotene in a traditional peanut oil (cultivar Virginia, 30.5% linoleic acid) with a modified high-oleic peanut oil (cultivar SunOleic, 2.7% linoleic acid), developed in Florida, USA. The initial contents of tocopherols and trace lipid oxidation products, including hydroperoxides, were of the same order in both oils. The stability against oxidation was tested under the conditions of the Schaal Oven Test at 40 and 60°C, in emulsion, using AOM, Rancimat, and the apparatus Oxipres at 100°C. Tocopherols were determined using HPLC with an electrochemical detection (without previous saponification). The high-oleic peanut oil SunOleic was about 4-8 times more stable against oxidation than the traditional peanut oil Virginia. The contents of total tocopherols were 303 mg/kg in Virginia oil and 426 mg/kg in SunOleic oil, respectively. Ratios of poměr a- : g - : d-tocopherols were rather similar in both oils. Thus, the observed differences in the oxidative stabilities cannot be due to tocopherols only. The decomposition of tocopherols in peanut oils, containing an addition of 500 mg/kg b-tocopherol, on storage was substantially slower in high-oleic SunOleic peanut oil than in Virginia peanut oil. Very similar results were observed in the case of the additions of 50 mg/kg -carotene to peanut oil. The vitamin value was much better preserved in high-oleic peanut oil than in traditional peanut oil. Keywords: antioxidants, autoxidation, carotene, peanut oil, storage, tocopherols Journal: Czech Journal of Food Sciences Pages: 19-27 Volume: 21 Issue: 1 Year: 2003 DOI: 10.17221/3473-CJFS File-URL: http://cjfs.agriculturejournals.cz/doi/10.17221/3473-CJFS.html File-Format: text/html Handle: RePEc:caa:jnlcjf:v:21:y:2003:i:1:id:3473-CJFS Template-Type: ReDIF-Article 1.0 Author-Name: M. Hrušková Author-Workplace-Name: Department of Carbohydrate Chemistry and Technology, Institute of Chemical Technology, Praque, Czech Republic Author-Name: P. Šmejda Author-Workplace-Name: Department of Carbohydrate Chemistry and Technology, Institute of Chemical Technology, Praque, Czech Republic Title: Wheat flour dough alveograph characteristics predicted by NIRSystems 6500 Abstract: Rheological quality of wheat dough prepared from 130 variety, stream, and commercial wheat flour samples (wheat harvest 1999, 2000 and 2001) was assessed with alveograph. Spectra of all samples were measured on spectrograph NIRSystems 6500. Calibration equations with cross and independent validation for all rheological characteristics were computed by NIR Software ISI Present WINISI II using MPLS and PLS methods. The quality of the prediction was evaluated by the coefficient of correlation between the measured and the predicted values from cross and independent validation. A statistically significant dependence between the predicted and the measured values (with probability P < 0.01) was determined in P (elasticity) and W (energy) characteristics in the case of cross validation only in the commercial flour sets. P (with P < 0.01) and W (with P < 0.05) were successfully predicted by independent validation in the set of all samples. Keywords: wheat flour dough, alveograph, NIRSystems 6500, prediction of rheological characteristics Journal: Czech Journal of Food Sciences Pages: 28-33 Volume: 21 Issue: 1 Year: 2003 DOI: 10.17221/3474-CJFS File-URL: http://cjfs.agriculturejournals.cz/doi/10.17221/3474-CJFS.html File-Format: text/html X-File-Ref: http://agriculturejournals.cz/RePEc/caa/references/cjf-200301-0004.txt Handle: RePEc:caa:jnlcjf:v:21:y:2003:i:1:id:3474-CJFS Template-Type: ReDIF-Article 1.0 Author-Name: J. Česnek Author-Workplace-Name: Romill, s.r.o., Brno, Czech Republic Author-Name: J. Dobiáš Author-Workplace-Name: Romill, s.r.o., Brno, Czech Republic Author-Name: J. Houšová Author-Workplace-Name: Romill, s.r.o., Brno, Czech Republic Author-Name: J. Sedláček Author-Workplace-Name: Romill, s.r.o., Brno, Czech Republic Title: Properties of thin metallic films for microwave susceptors Abstract: Thin Al films of varying thickness, i.e. 3 to 30 nm, were deposited onto polyethylene-terephthalate film by evaporation in the vacuum of 3 × 10-3 Pa. The dependence of DC (direct current) surface resistance on thickness was measured using a four-point method. The surface resistance exhibits the size effect in accordance with the Fuchs-Sondheimer theory. The microwave absorption properties of the prepared films of various metallization thickness were measured in a microwave field at the microwave power of 1.8 mW. The maximum microwave absorption at 2.45 GHz was found to occur in a layer of optical density of about 0.22. Keywords: microwave susceptors, food packaging, optical density, DC surface resistance, microwave absorption Journal: Czech Journal of Food Sciences Pages: 34-40 Volume: 21 Issue: 1 Year: 2003 DOI: 10.17221/3475-CJFS File-URL: http://cjfs.agriculturejournals.cz/doi/10.17221/3475-CJFS.html File-Format: text/html X-File-Ref: http://agriculturejournals.cz/RePEc/caa/references/cjf-200301-0005.txt Handle: RePEc:caa:jnlcjf:v:21:y:2003:i:1:id:3475-CJFS