Template-Type: ReDIF-Article 1.0 Author-Name: K. Surówka Author-Workplace-Name: Department of Refrigeration and Food Concentrates, Faculty of Food Technology, Agricultural University of Cracow, Cracow, Poland Author-Name: D. Żmudziński Author-Workplace-Name: Department of Refrigeration and Food Concentrates, Faculty of Food Technology, Agricultural University of Cracow, Cracow, Poland Title: functional properties modification of extruded soy protein concentrate using Neutrase Abstract: Enzymic hydrolysis of extruded soy protein concentrate with Neutrase was used for the preparation new soy protein products with modified functional properties. After the determination of optimum values of pH as 6.8; temperature as 50°C, and water addition as 13.3 kg/kg protein, the response surface methodology with enzyme:substrate ratio and time as independent variables was used to establish optimal conditions of the process. Solubility, water holding capacity (WHC), back extrusion work (BEW) as well as emulsifying (BAI, ESI) and foaming (FO) properties were taken as optimisation criteria. It was found difficult to obtain an ideal product by combining all the best features due to the multidirectional effect of hydrolysis on the changes of various functional properties. Nevertheless, optimal hydrolysate can be obtained at relatively low additions of Neutrase to the extrudate (e.g., 18 mAU/g protein) and in short time (e.g. 60 min). Under such conditions, the process provides a product containing 0.8 mmol amino nitrogen/g protein, which combines the features of a protein hydrolysate and those of an extrudate. SDS-PAGE of the optimal hydrolysate revealed that proteolysis of the extruded concentrate was more extensive than proteolysis of its counterpart which was not subjected to extrusion. Keywords: limited proteolysis, Neutrase, soy protein, functional properties, process optimisation, extrusion Journal: Czech Journal of Food Sciences Pages: 163-174 Volume: 22 Issue: 5 Year: 2004 DOI: 10.17221/3420-CJFS File-URL: http://cjfs.agriculturejournals.cz/doi/10.17221/3420-CJFS.html File-Format: text/html X-File-Ref: http://agriculturejournals.cz/RePEc/caa/references/cjf-200405-0001.txt Handle: RePEc:caa:jnlcjf:v:22:y:2004:i:5:id:3420-CJFS Template-Type: ReDIF-Article 1.0 Author-Name: M. Holasová Author-Workplace-Name: Food Research Institute Prague, Prague, Czech Republic Author-Name: V. Fiedlerová Author-Workplace-Name: Food Research Institute Prague, Prague, Czech Republic Author-Name: P. Roubal Author-Workplace-Name: Food Research Institute Prague, Prague, Czech Republic Author-Name: M. Pechačová Author-Workplace-Name: Food Research Institute Prague, Prague, Czech Republic Title: biosynthesis of folates by lactic acid bacteria and propionibacteria in fermented milk Abstract: Folate producing ability of several strains of Bifidobacterium longum, Bifidobacterium bifidum, Streptococcus thermophilus and Propionibacterium freudenreichii subsp. shermanii was evaluated. As substrate, UHT milk with 1.5% fat content treated with additional laboratory sterilisation was used. Fermentation was conducted at 37°C and 30°C in the case of Propionibacterium. 5-Methyltetrahydrofolate (5-MTHF) concentrations were determined using HPLC method. All strains of Streptococcus thermophilus tested showed 5-MTHF production. More than six-fold increase was found in the 5-MTHF content in comparison with control (increase = 3.69 µg 5-MTHF/100 g) after 12 h fermentation. Bifidobacterium longum strains were recognised as mild folate producers with max. 73% increase in the 5-MTHF content (increase = 0.48 µg 5-MTHF/100 g) after 12 h fermentation. The Propionibacterium freudenreichii subsp. shermanii strains tested did not basically influence the 5-MTHF levels during milk fermentation. In all cases, maximum 5-MTHF concentration was reached between 6 and 12 hours of fermentation. Large differences in the 5-MTHF production were found among individual strains within species. By a careful testing of the folate production ability of microbial strains used in the production of fermented milk, an enhancement of the natural folate content can be achieved. Keywords: folate, fermentation, milk Journal: Czech Journal of Food Sciences Pages: 175-181 Volume: 22 Issue: 5 Year: 2004 DOI: 10.17221/3421-CJFS File-URL: http://cjfs.agriculturejournals.cz/doi/10.17221/3421-CJFS.html File-Format: text/html X-File-Ref: http://agriculturejournals.cz/RePEc/caa/references/cjf-200405-0002.txt Handle: RePEc:caa:jnlcjf:v:22:y:2004:i:5:id:3421-CJFS Template-Type: ReDIF-Article 1.0 Author-Name: V. Divinová Author-Workplace-Name: Department of Food Chemistry and Analysis, Faculty of Food and Biotechnological Technology, Institute of Chemical Technology in Prague, Prague, Czech Republic Author-Name: B. Svejkovská Author-Workplace-Name: Department of Food Chemistry and Analysis, Faculty of Food and Biotechnological Technology, Institute of Chemical Technology in Prague, Prague, Czech Republic Author-Name: M. Doležal Author-Workplace-Name: Department of Food Chemistry and Analysis, Faculty of Food and Biotechnological Technology, Institute of Chemical Technology in Prague, Prague, Czech Republic Author-Name: J. Velíšek Author-Workplace-Name: Department of Food Chemistry and Analysis, Faculty of Food and Biotechnological Technology, Institute of Chemical Technology in Prague, Prague, Czech Republic Title: Determination of free and bound 3-chloropropane-1,2-diol by gas chromatography with mass spectrometric detection using deuterated 3-chloropropane-1,2-diol as internal standard Abstract: An improved routine, simple and sensitive method is presented for the determination of free and bound 3-chloropropane-1,2-diol (3-MCPD) in different foods using capillary gas chromatography with mass spectrometric detection and deuterated 3-MCPD as internal standard. The optimised method was linear within the working calibration standard concentrations in the range of 0.009-1.3 mg 3-MCPD per 1 kg of sample. The LOD and LOQ were 0.003 µg/kg and 0.009 µg/kg, respectively. Validation of the method was carried out by analysing standards of 3-MCPD, acid-HVP, roasted coffee samples, and the same samples spiked with 3-MCPD. Repeatability (expressed as RSD) of the method was in the range 1.0-4.2%, the average spike recoveries were 99.1-99.5% (RSD = 0.8-1.4%), respectively. 3-MCPD bound in esters with higher fatty acids was isolated as fat, the isolated fat was subjected to methanolysis and 3-MCPD generated was quantified using the same method. The LOD and LOQ were determined to be 1.1 mg/kg of lipids and 3.3 mg/kg of lipids, respectively. Using the optimised method, 20 samples of retail food products were analysed for their free and bound 3-MCPD. All samples contained free 3-MCPD at 9.6-83 µg/kg (RSD = 0.4-7.0%). The level of the bound 3-MCPD varied between the LOD and 2.4 mg/kg with RSD = 0.3-2.4%. Keywords: 3-chloropropane-1, 2-diol (3-MCPD), chloropropanediols, 3-MCPD esters, phenylboronic acid, food analysis Journal: Czech Journal of Food Sciences Pages: 182-189 Volume: 22 Issue: 5 Year: 2004 DOI: 10.17221/3422-CJFS File-URL: http://cjfs.agriculturejournals.cz/doi/10.17221/3422-CJFS.html File-Format: text/html X-File-Ref: http://agriculturejournals.cz/RePEc/caa/references/cjf-200405-0003.txt Handle: RePEc:caa:jnlcjf:v:22:y:2004:i:5:id:3422-CJFS Template-Type: ReDIF-Article 1.0 Author-Name: B. Svejkovská Author-Workplace-Name: Department of Food Chemistry and Analysis, Faculty of Food and Biotechnological Technology, Institute of Chemical Technology in Prague, Prague, Czech Republic Author-Name: O. Novotný Author-Workplace-Name: Department of Food Chemistry and Analysis, Faculty of Food and Biotechnological Technology, Institute of Chemical Technology in Prague, Prague, Czech Republic Author-Name: V. Divinová Author-Workplace-Name: Department of Food Chemistry and Analysis, Faculty of Food and Biotechnological Technology, Institute of Chemical Technology in Prague, Prague, Czech Republic Author-Name: Z. Réblová Author-Workplace-Name: Department of Food Chemistry and Analysis, Faculty of Food and Biotechnological Technology, Institute of Chemical Technology in Prague, Prague, Czech Republic Author-Name: M. Doležal Author-Workplace-Name: Department of Food Chemistry and Analysis, Faculty of Food and Biotechnological Technology, Institute of Chemical Technology in Prague, Prague, Czech Republic Author-Name: J. Velíšek Author-Workplace-Name: Department of Food Chemistry and Analysis, Faculty of Food and Biotechnological Technology, Institute of Chemical Technology in Prague, Prague, Czech Republic Title: Esters of 3-chloropropane-1,2-diol in foodstuffs Abstract: We provide here for the first time the evidence that 3-chloropropane-1,2-diol (3-MCPD) occurs in foodstuffs in its free form and also in the form of esters with higher fatty acids. These esters represent a new class of food contaminants as 3-MCPD may be released in vivoby a lipase-catalysed hydrolysis reaction. We analysed 20 samples of selected retail food products for their free and bound 3-MCPD content. All samples contained free 3-MCPD at approximately 9.6-82.7 µg/kg food (3 replications, RSD = 0.4-7.0%). The levels of bound 3-MCPD (monoesters and diesters of 3-MCPD with higher fatty acids) found in the foodstuffs analysed varied between the LOD (1.1 mg per kg of fat) and 36.8 mg/kg fat with RSD = 0.3-3.3%. Five foodstuffs of plant origin processed at high temperatures contained elevated levels of bound 3-MCPD (0.14-6.10 mg/kg). A high level of bound 3-MCPD (0.28 mg/kg) was also found in a sample of pickled fish. Some variables potentially influencing the levels of either free or bound 3-MCPD in foodstuffs were determined (pH, water, chlorides, glycerol, fat and its components) and their significance was discussed. Keywords: 3-chloropropane-1, 2-diol (3-MCPD), chloropropanediols, chlorolipids, 3-MCPD esters, 3-MCPD mono-esters, 3-MCPD diesters Journal: Czech Journal of Food Sciences Pages: 190-196 Volume: 22 Issue: 5 Year: 2004 DOI: 10.17221/3423-CJFS File-URL: http://cjfs.agriculturejournals.cz/doi/10.17221/3423-CJFS.html File-Format: text/html X-File-Ref: http://agriculturejournals.cz/RePEc/caa/references/cjf-200405-0004.txt Handle: RePEc:caa:jnlcjf:v:22:y:2004:i:5:id:3423-CJFS