Template-Type: ReDIF-Article 1.0 Author-Name: Jan Velíšek Author-Workplace-Name: Department of Food Chemistry and Analysis, Faculty of Food and Biochemical Technology, Institute of Chemical Technology in Prague, Prague, Czech Republic Author-Name: Karel Cejpek Author-Workplace-Name: Department of Food Chemistry and Analysis, Faculty of Food and Biochemical Technology, Institute of Chemical Technology in Prague, Prague, Czech Republic Title: Biosynthesis of food constituents: Vitamins. 2. Water-soluble vitamins: Part 2 - a review Abstract: This review article gives a survey of the biosynthetic pathways that lead to water-soluble vitamins in microorganisms, plants and some animals. The biosynthetic pathways leading to some the B-group vitamins (biotin, folacin, cobalamins) and to vitamin C are described in detail using reaction schemes and mechanisms with enzymes involved and detailed explanations based on chemical principles and mechanisms. Keywords: biosynthesis, B-group vitamins, biotin, folates, folic acid, cobalamins, vitamin B12, vitamin C, L-ascorbic acid, D-erythro-ascorbic acid Journal: Czech Journal of Food Sciences Pages: 101-118 Volume: 25 Issue: 3 Year: 2007 DOI: 10.17221/744-CJFS File-URL: http://cjfs.agriculturejournals.cz/doi/10.17221/744-CJFS.html File-Format: text/html X-File-Ref: http://agriculturejournals.cz/RePEc/caa/references/cjf-200703-0001.txt Handle: RePEc:caa:jnlcjf:v:25:y:2007:i:3:id:744-CJFS Template-Type: ReDIF-Article 1.0 Author-Name: Ondřej Novotný Author-Workplace-Name: Department of Food Chemistry and Analysis, Faculty of Food and Biochemical Technology, Institute of Chemical Technology in Prague, Prague, Czech Republic Author-Name: Karel Cejpek Author-Workplace-Name: Department of Food Chemistry and Analysis, Faculty of Food and Biochemical Technology, Institute of Chemical Technology in Prague, Prague, Czech Republic Author-Name: Jan Velíšek Author-Workplace-Name: Department of Food Chemistry and Analysis, Faculty of Food and Biochemical Technology, Institute of Chemical Technology in Prague, Prague, Czech Republic Title: Formation of α-hydroxycarbonyl and α-dicarbonyl compounds during degradation of monosaccharides Abstract: The formation of α-hydroxycarbonyl and α-dicarbonyl compounds from monosaccharides (glucose, fructose, arabinose, glyceraldehyde, and 1,3-dihydroxyacetone) was studied in three different model systems comprising an aqueous and alkaline solution of potassium peroxodisulfate (K2S2O8), and a solution of sodium hydroxide, respectively. In total, six α-hydroxycarbonyl (in the form of O-ethyloximes) and six α-dicarbonyl compounds (as quinoxaline derivatives) were identified by GC/MS and quantified. Acetol, glycolaldehyde, 1,3-dihydroxyacetone, methylglyoxal, and glyoxal were the most abundant low molecular weight carbonyls. Within the model systems studied, the yield of α-hydroxycarbonyl and α-dicarbonyl compounds was 0.32-4.90% (n/n) and 0.35-9.81% (n/n), respectively. The yield of α-dicarbonyls was higher than that of α-hydroxycarbonyls only in aqueous solution of K2S2O8 and in the other two model systems an inverse ratio of these two carbonyl types was found. For the first time, ethylglyoxal was identified as a sugar degradation product and several mechanisms explaining its formation were proposed. The achieved data indicated that low molecular weight α-hydroxycarbonyl and α-dicarbonyl compounds are predominantly formed by a direct retro-aldol reaction and α- and β-dicarbonyl cleavage. It was evident that some compounds were produced from the sugar fragmentation products. Thus, isomerisation, reduction of dicarbonyls by formaldehyde (cross-Cannizzaro reaction), and mutual disproportionation are possible reaction pathways participating in the formation of α-hydroxycarbonyl compounds. Oxidation and disproportionation of α-hydroxycarbonyl precursors as well as the aldol condensation of low molecular weight carbonyl species (followed by subsequent reactions) play an important role in the formation of several α-dicarbonyl compounds. Keywords: monosaccharides, α -hydroxycarbonyl compounds, -dicarbonyl compounds, retro-aldol reaction, peroxodisulfate, acetol, 1, 3-dihydroxyacetone, glyceraldehyde, glycolaldehyde, acetoin, 1-hydroxybutan-2-one, lactaldehyde, glyoxal, methylglyoxal, ethylglyoxal, butane-2, 3-dione, 1-hydroxybutane-2, pentane-2 Journal: Czech Journal of Food Sciences Pages: 119-130 Volume: 25 Issue: 3 Year: 2007 DOI: 10.17221/740-CJFS File-URL: http://cjfs.agriculturejournals.cz/doi/10.17221/740-CJFS.html File-Format: text/html X-File-Ref: http://agriculturejournals.cz/RePEc/caa/references/cjf-200703-0002.txt Handle: RePEc:caa:jnlcjf:v:25:y:2007:i:3:id:740-CJFS Template-Type: ReDIF-Article 1.0 Author-Name: Jana Horváthová Author-Workplace-Name: Food Research Institute, Bratislava, Slovak Republic, Author-Name: Milan Suhaj Author-Workplace-Name: Food Research Institute, Bratislava, Slovak Republic, Author-Name: Martin Polovka Author-Workplace-Name: Food Research Institute, Bratislava, Slovak Republic, Author-Name: Vlasta Brezová Author-Workplace-Name: Institute of Physical Chemistry and Chemical Physics, Faculty of Chemical and Food Technology, Slovak University of Technology, Bratislava, Slovak Republic Author-Name: Peter Šimko Author-Workplace-Name: Food Research Institute, Bratislava, Slovak Republic, Title: The influence of gamma-irradiation on the formation of free radicals and antioxidant status of oregano (Origanum vulgare L.) Abstract: The influence of various gamma-radiation dose absorptions on oregano (Origanum vulgare L.) solid samples was monitored by means of electron paramagnetic resonance (EPR) spectroscopy. Further, the antioxidant activity of oregano methanol/water extracts was characterised using DPPH (1,1-diphenyl-2-picrylhydrazyl free radical); thiobarbituric acid reactive substances (TBARS); ferric reducing power (FRP); and total content of phenolic compounds (TPC) assays. EPR spectroscopy was used for the investigation of the influence of the absorbed dose on the character of the paramagnetic structures formed, as well as for their thermal stability and life-time characterisation. EPR spectrum of the reference (non-irradiated) sample represents a broad singlet line with unresolved hyperfine splitting, attributable to Mn(II) ions, upon which the additional sharp EPR signal (g = 2.0022, ΔBpp ≍ 1 mT) is superimposed, assigned to stable semiquinone radicals produced by the oxidation of polyphenolic compounds present in plants. The additional paramagnetic structures of different origin (mostly of cellulose and carbohydrate), possessing diverse thermal stability and life-time, were identified in the gamma-irradiated samples. Immediately after irradiation, a statistically significant increase was observed of the TBARS values and the total content of phenolic compounds in methanol/water oregano extract. The alterations of the antioxidant properties of oregano extracts with the time after the radiation treatment were also monitored. A substantial time-dependent decrease of antioxidant activity was observed, probably as a result of storage, with both irradiated and non-irradiated oregano samples, as obvious from the ferric reducing power test and the content of total phenolic substances. The influence of irradiation and subsequent storage of oregano samples on the DPPH radical-scavenging ability was only negligible. Keywords: oregano, irradiation, EPR spectroscopy, free radicals, thermal stability, life-time, antioxidant activity Journal: Czech Journal of Food Sciences Pages: 131-143 Volume: 25 Issue: 3 Year: 2007 DOI: 10.17221/741-CJFS File-URL: http://cjfs.agriculturejournals.cz/doi/10.17221/741-CJFS.html File-Format: text/html X-File-Ref: http://agriculturejournals.cz/RePEc/caa/references/cjf-200703-0003.txt Handle: RePEc:caa:jnlcjf:v:25:y:2007:i:3:id:741-CJFS Template-Type: ReDIF-Article 1.0 Author-Name: Halil Kizilaslan Author-Workplace-Name: Department of Agricultural Economics, Faculty of Agriculture, Gaziosmanpasa University, Tokat, Turkey Author-Name: Nuray Kizilaslan Author-Workplace-Name: Department of Agricultural Economics, Faculty of Agriculture, Gaziosmanpasa University, Tokat, Turkey Title: Risk analysis in Turkey milk production Abstract: The present study has been done in order to determine the risks inherent in the milk production in Turkey. For that objective, factors such as the milk yield, the gross revenues realised, and the price levels as reflected to the producer's benefits, have been taken into account. Upon the calculation of the measures for variables, fluctuations were found in the milk yield, prices, and gross revenues. Based on the hypothesis that the information possessed by the producer on the economic and technological developments is scarce and restrained, the variable coefficient has been calculated as 10.81% for yield, 23.26% for prices, and 30.01% for gross revenues, respectively. With the hypothesis that the producers are aware of and informed on the economic and technological developments, these ratios, that is to say, the fortuitous variable coefficients would be, respectively, 2.07%, 15.96%, and 16.07%. According to the conclusions reached, an environment in which the producers can take rational decisions concerning the milk production can be said not to exist. For this reason, the government intervention through efficient measures for the dairy production will be necessary. Furthermore, the producers should be given informational support through the published studies in the agricultural extension. Keywords: dairy production, risk, uncertainty, Turkey, agricultural extension Journal: Czech Journal of Food Sciences Pages: 144-150 Volume: 25 Issue: 3 Year: 2007 DOI: 10.17221/743-CJFS File-URL: http://cjfs.agriculturejournals.cz/doi/10.17221/743-CJFS.html File-Format: text/html X-File-Ref: http://agriculturejournals.cz/RePEc/caa/references/cjf-200703-0004.txt Handle: RePEc:caa:jnlcjf:v:25:y:2007:i:3:id:743-CJFS Template-Type: ReDIF-Article 1.0 Author-Name: Žaneta Ugarčić-Hardi Author-Workplace-Name: Faculty of Food Technology, Josip Juraj Strossmayer University of Osijek, Osijek, Croatia Author-Name: Marko Jukić Author-Workplace-Name: Faculty of Food Technology, Josip Juraj Strossmayer University of Osijek, Osijek, Croatia Author-Name: Daliborka Koceva Komlenić Author-Workplace-Name: Faculty of Food Technology, Josip Juraj Strossmayer University of Osijek, Osijek, Croatia Author-Name: Mirjana Sabo Author-Workplace-Name: Faculty of Food Technology, Josip Juraj Strossmayer University of Osijek, Osijek, Croatia Author-Name: Jovica Hardi Author-Workplace-Name: Faculty of Food Technology, Josip Juraj Strossmayer University of Osijek, Osijek, Croatia Title: Quality parameters of noodles made with various supplements Abstract: The influence of various supplements (extruded maize, maize, defatted soy flour and maize/soy flour blends, lecithin and wheat straw) on the pasta quality has been examined. Noodles were prepared by means of conventional laboratory equipment. Common wheat flour supplemented with 1% lecithin powder, 20% extruded maize flour, 20% maize flour, 10% defatted soy flour, 20% defatted soy and maize flour blend (1:1), and 7.5% wheat straw was used. The produced pasta was dried at 55&grad;C in a laboratory dryer (Instrumentaria, Croatia) to 13.0% moisture. Pasta colour was evaluated with fresh pasta by measuring L*, a*, b* parameters by means of a reflectance colorimeter (CR 300 Chroma-metter, Minolta, Japan). The following parameters of cooked noodles were determined: volume increase coefficient, water uptake (g/g), optimum cooking time (min), and cooking loss (%). Sensory quality was evaluated on a scale of 1-5 for: odour, external appearance, flavour and mouth feel, and total quality scores. The noodles made with extruded maize flour, maize flour, and wheat straw supplements had the highest total sensory score. Cooking losses of these samples were below 10%. Regardless of the fact that the sample with lecithin had the lowest cooking loss, it was not acceptable for the panel members. Supplementation with extruded maize, maize and defatted soy flours, and wheat straw could be used to produce pasta without eggs, with a reduced cholesterol content, enriched with dietary fibre and possessing a lower glycemic index. Keywords: noodle with supplements, colour parameters, cooking properties Journal: Czech Journal of Food Sciences Pages: 151-157 Volume: 25 Issue: 3 Year: 2007 DOI: 10.17221/742-CJFS File-URL: http://cjfs.agriculturejournals.cz/doi/10.17221/742-CJFS.html File-Format: text/html X-File-Ref: http://agriculturejournals.cz/RePEc/caa/references/cjf-200703-0005.txt Handle: RePEc:caa:jnlcjf:v:25:y:2007:i:3:id:742-CJFS