Template-Type: ReDIF-Article 1.0 Author-Name: J. Velíšek Author-Workplace-Name: Department of Food Chemistry and Analysis - Institute of Chemical Technology, Prague; Central Science Laboratory, Sand Hutton, York, Great Britain Author-Name: M. Doležal Author-Workplace-Name: Department of Food Chemistry and Analysis - Institute of Chemical Technology, Prague; Central Science Laboratory, Sand Hutton, York, Great Britain Author-Name: C. Crews Author-Workplace-Name: Department of Food Chemistry and Analysis - Institute of Chemical Technology, Prague; Central Science Laboratory, Sand Hutton, York, Great Britain Author-Name: T. Dvořák Author-Workplace-Name: Department of Food Chemistry and Analysis - Institute of Chemical Technology, Prague; Central Science Laboratory, Sand Hutton, York, Great Britain Title: Optical isomers of chloropropanediols: mechanisms of their formation and decomposition in protein hydrolysates Abstract: Protein hydrolysates produced by hydrochloric acid hydrolysis were analysed for 3-chloropropane-1,2-diol and its enantiomers. It was found that (R)-3-chloropropane-1,2-diol and (S)-3-chloropropane-1,2-diol were present in the hydrolysates in equimolar concentrations. Model experiments with glycerol, triolein and soy lecithin heated with hydrochloric acid in solution showed that these materials were precursors of 3-chloropropane-1,2-diol and 2-chloropropane-1,3-diol and, as expected, yielded racemic 3-chloropropane-1,2-diol. Yields of 3-chloropropane-1,2-diols decreased in the order triolein > lecithin > glycerol. The mechanisms of 3-chloropropane-1,2-diol enantiomers formation during the production of protein hydrolysates are presented and discussed as well as the reaction pathways of their decomposition in alkaline media via the corresponding intermediates, (R)- and (S)-glycidol, respectively. Both epoxides are hydrolysed to glycerol and form a variety of products with hydrolysate constituents. Keywords: chloropropanediols, chloropropanols, 3-chloropropane-1, 2-diol, 2-chloropropane-1, 3-diol, glycidol, MCPD, enantiomers, protein hydrolysates Journal: Czech Journal of Food Sciences Pages: 161-170 Volume: 20 Issue: 5 Year: 2002 DOI: 10.17221/3527-CJFS File-URL: http://cjfs.agriculturejournals.cz/doi/10.17221/3527-CJFS.html File-Format: text/html X-File-Ref: http://agriculturejournals.cz/RePEc/caa/references/cjf-200205-0001.txt Handle: RePEc:caa:jnlcjf:v:20:y:2002:i:5:id:3527-CJFS Template-Type: ReDIF-Article 1.0 Author-Name: E. Vlková Author-Workplace-Name: Czech University of Agriculture - Department of Microbiology and Biotechnology, Prague, Czech Republic Author-Name: J. Medková Author-Workplace-Name: Czech University of Agriculture - Department of Microbiology and Biotechnology, Prague, Czech Republic Author-Name: V. Rada Author-Workplace-Name: Czech University of Agriculture - Department of Microbiology and Biotechnology, Prague, Czech Republic Title: Comparison of four methods for identification of bifidobacteria to the genus level Abstract: The identification of bifidobacteria to the genus level is important for the differentiation of these bacteria from other bacteria occurring in the animal and human intestine. The detection of fructose-6-phosphate phosphoketolase (F6PPK-test) is used traditionally for the identification of Bifidobacterium sp. The original procedure is time consuming and therefore it was modified several times recently. The aim of the present work was to compare the following methods for the genus identification of bifidobacteria: F6PPK-test, F6PPK-test modified by the addition of triton X-100, F6PPK-test modified by the addition of cetridium bromide (F6PPK-CTAB-test), and PCR using genus specific primers. Bifidobacteria isolated from fermented milk products (3 strains), human faeces (6 strains), and animal intestinal tract (2 strains) were tested. All the methods tested proved to be reliable tests for the genus identification of bifidobacteria. The F6PPK-CTAB-test gave the best results. This procedure is quick and does not require any special laboratory equipment. Keywords: bifidobacteria, identification, fructose-6-phosphate phosphoketolase test, CTAB, Triton X-100, PCR Journal: Czech Journal of Food Sciences Pages: 171-174 Volume: 20 Issue: 5 Year: 2002 DOI: 10.17221/3528-CJFS File-URL: http://cjfs.agriculturejournals.cz/doi/10.17221/3528-CJFS.html File-Format: text/html X-File-Ref: http://agriculturejournals.cz/RePEc/caa/references/cjf-200205-0002.txt Handle: RePEc:caa:jnlcjf:v:20:y:2002:i:5:id:3528-CJFS Template-Type: ReDIF-Article 1.0 Author-Name: B. Tremlová Author-Workplace-Name: 2 BOHUSLAVA TREMLOVÁ and PAVEL ŠTARHA Author-Name: P. Štarha Author-Workplace-Name: 2 BOHUSLAVA TREMLOVÁ and PAVEL ŠTARHA Title: Histometric evaluation of meat products - determination of size and number of objects Abstract: In the framewort of the quantitative histologic evaluation of poultry products, the size and the number of bone fragments have been determined using the image analysis. Bone fragments were identified by their colour and analysed automatically. The samples contained 135 to 2167 bone particles the length of which varied from 5 to 2088 μm. Comparing products of the same kind, we found differences in the contents of bone fragments; this fact was possibly due to inadequate observance of the technological procedure by some producers. Keywords: image analysis, histological evaluation, poultry products, bone fragments Journal: Czech Journal of Food Sciences Pages: 175-180 Volume: 20 Issue: 5 Year: 2002 DOI: 10.17221/3529-CJFS File-URL: http://cjfs.agriculturejournals.cz/doi/10.17221/3529-CJFS.html File-Format: text/html X-File-Ref: http://agriculturejournals.cz/RePEc/caa/references/cjf-200205-0003.txt Handle: RePEc:caa:jnlcjf:v:20:y:2002:i:5:id:3529-CJFS Template-Type: ReDIF-Article 1.0 Author-Name: P. Šmerák Author-Workplace-Name: 3 Faculty of Medicine, Charles University, Prague; National Institute of Public Health, Prague, Czech Republic Author-Name: H. Šestáková Author-Workplace-Name: 3 Faculty of Medicine, Charles University, Prague; National Institute of Public Health, Prague, Czech Republic Author-Name: Z. Polívková Author-Workplace-Name: 3 Faculty of Medicine, Charles University, Prague; National Institute of Public Health, Prague, Czech Republic Author-Name: I. Bárta Author-Workplace-Name: 3 Faculty of Medicine, Charles University, Prague; National Institute of Public Health, Prague, Czech Republic Author-Name: B. Turek Author-Workplace-Name: 3 Faculty of Medicine, Charles University, Prague; National Institute of Public Health, Prague, Czech Republic Author-Name: J. Bártová Author-Workplace-Name: 3 Faculty of Medicine, Charles University, Prague; National Institute of Public Health, Prague, Czech Republic Author-Name: M. Langová Author-Workplace-Name: 3 Faculty of Medicine, Charles University, Prague; National Institute of Public Health, Prague, Czech Republic Author-Name: M. Anděl Author-Workplace-Name: 3 Faculty of Medicine, Charles University, Prague; National Institute of Public Health, Prague, Czech Republic Title: Antimutagenic effect of ellagic acid and its effect on the immune response in mice Abstract: Using the Ames bacterial mutagenicity test and an in vivo micronucleus test, we investigated the antigenotoxic effect of ellagic acid on the genotoxicity of three mutagens: amino-methylimidazo-quinoline (IQ), aflatoxin B1 (AFB1), and N-nitroso-N-methylurea (MNU). Ellagic acid is a naturally occurring phenolic compound which is found in a variety of soft fruits and vegetables. The effect of this compound on the immunosuppressive activity of mutagens was followed in vivo by the chemiluminescence test. In the Ames assay, ellagic acid at concentrations of 300 and 30 μg/plate demonstrably inhibits the mutagenic activity of two indirect mutagens: IQ and AFB1. The concentration of 300 μg/plate had the strongest effect on mutagenicity of all concentrations of IQ in strain TA98 of Salmonella typhimurium, whereas in strain TA100 concentration of 30 μg per dish of ellagic acid was more effective than 300 μg per plate. Also in combination with different concentrations of AFB1, ellagic acid proved to be a strong antimutagen. In this case the lower of the two effective concentrations - 30 μg/plate - had a much greater antimutagenic effect on both strains tested than 300 μg/plate. In combination with the direct mutagen MNU, ellagic acid did not show any marked antimutagenic effect at most of the concentrations tested in strain TA100. Only the highest concentrations of ellagic acid reduced the mutagenic effect of MNU weakly and only in combination with two lower concentrations of MNU. In the micronucleus test, three-day oral application of ellagic acid prior to the applicaton of AFB1, IQ, or MNU, respectively, markedly reduced the numbers of micronuclei induced by these three mutagens in polychromatophilic erythrocytes of mice. Chemiluminescence test with mouse granulocytes proved that ellagic acid not only prevents the inhibitory effects of mutagens on free oxygen radicals and hydrogen peroxide production, but that this production is stimulated by ellagic acid in combination with mutagens even to a greater extent than by ellagic acid alone. From these results we can deduce that ellagic acid repairs strong immunosuppressive effects of all mutagens applied. Keywords: ellagic acid, amino-methylimidazo-quinoline, aflatoxin B1, N-nitroso-N-methylurea, antimutagenic activity, chemiluminescence Journal: Czech Journal of Food Sciences Pages: 181-191 Volume: 20 Issue: 5 Year: 2002 DOI: 10.17221/3530-CJFS File-URL: http://cjfs.agriculturejournals.cz/doi/10.17221/3530-CJFS.html File-Format: text/html X-File-Ref: http://agriculturejournals.cz/RePEc/caa/references/cjf-200205-0004.txt Handle: RePEc:caa:jnlcjf:v:20:y:2002:i:5:id:3530-CJFS Template-Type: ReDIF-Article 1.0 Author-Name: A. Landfeld Author-Workplace-Name: Food Research Institute Prague, Prague, Czech Republic Author-Name: R. Žitný Author-Workplace-Name: Food Research Institute Prague, Prague, Czech Republic Author-Name: M. Houška Author-Workplace-Name: Food Research Institute Prague, Prague, Czech Republic Author-Name: K. Kýhos Author-Workplace-Name: Food Research Institute Prague, Prague, Czech Republic Author-Name: P. Novotná Author-Workplace-Name: Food Research Institute Prague, Prague, Czech Republic Title: Residence time distribution during egg yolk pasteurisation Abstract: This work describes the determination of the average residence times during egg yolk - and whole liquid eggs pasteurisation in an industrial pasteurisation equipment (plate pasteuriser + tube holder). For the detection of the impulse the conductivity method was used. Conductivity was then monitored using the bridge method. In the system, the total of 3 probes were placed. To mark the particles of the flowing product, salted yolk with the content of salt of 1.3 or 1.8% was used. In addition, rheological properties of pasteurised yolk were determined at the temperatures of 5, 25, 45, and 65°C. Based on the geometry of the channels in the individual sections of the pasteurisation equipment, the character of the flow was estimated using the Re criterion and was found to be laminar in all parts of the system. The work includes the comparison of the average residence times obtained by (a) the method of volumes, (b) the analysis of the conductivity response, (c) the estimate made by using the TUPLEX software, and (d) the estimate of the peaks of the conductivity response. Keywords: residence time, pasteurisation, egg yolks, tube flow Journal: Czech Journal of Food Sciences Pages: 193-201 Volume: 20 Issue: 5 Year: 2002 DOI: 10.17221/3531-CJFS File-URL: http://cjfs.agriculturejournals.cz/doi/10.17221/3531-CJFS.html File-Format: text/html X-File-Ref: http://agriculturejournals.cz/RePEc/caa/references/cjf-200205-0005.txt Handle: RePEc:caa:jnlcjf:v:20:y:2002:i:5:id:3531-CJFS Template-Type: ReDIF-Article 1.0 Author-Name: P. Novotná Author-Workplace-Name: Food Research Institute Prague, Prague, Czech Republic Author-Name: K. Kýhos Author-Workplace-Name: Food Research Institute Prague, Prague, Czech Republic Author-Name: A. Landfeld Author-Workplace-Name: Food Research Institute Prague, Prague, Czech Republic Author-Name: J. Strohalm Author-Workplace-Name: Food Research Institute Prague, Prague, Czech Republic Author-Name: M. Houška Author-Workplace-Name: Food Research Institute Prague, Prague, Czech Republic Title: Testing of scanner and colour-meter for observation of changes during storage of two selected foods Abstract: The test with colour and aroma of Kladno cooked pork loin stored in refrigerator and at the room temperature correspond with its spoilage was done. No change of the L* co-ordinate has been observed during the storage. A strong decrease of a* co-ordinate for red colour after 1-day storage has taken place for samples stored in a room (approx. 25°C). Conversely, an increase of b* coordinate for yellow colour has been observed after 1-day storage. A change of the cooked pork loin aroma has also been noticed after 1-day storage using the sensory observation. Further, the possibility has been tested of using a portable scanner for the determination of banana colour changes. It has been found that the optimal storage temperature from the peel colour point of view is 14°C; it is in accordance with recommendations in literature. Keywords: colour, aroma, brightness, a* co-ordinate for red colour, b* co-ordinate for yellow colour Journal: Czech Journal of Food Sciences Pages: 203-208 Volume: 20 Issue: 5 Year: 2002 DOI: 10.17221/3532-CJFS File-URL: http://cjfs.agriculturejournals.cz/doi/10.17221/3532-CJFS.html File-Format: text/html X-File-Ref: http://agriculturejournals.cz/RePEc/caa/references/cjf-200205-0006.txt Handle: RePEc:caa:jnlcjf:v:20:y:2002:i:5:id:3532-CJFS