Template-Type: ReDIF-Article 1.0 Author-Name: I. Jančářová Author-Name: A. Vondráčková Author-Name: A. Šlampová Author-Name: V. Kubáň Title: Capillary electrophoretic and liquid chromatographic determination of synthetic dyes in non-alcoholic drinks and wine samples Abstract: Synthetic dyes in wine, juices, lemonades, instant and non-alcoholic drinks were determined by capillary electrophoresis (CE) and liquid chromatography (HPLC) with UV-VIS diode-array detection (DAD). The results were in the very good agreement (the relative deviations D < 16%, D < 14% and D < 15% between CE/UV-VIS, CE/HPLC and HPLC/UV-VIS, respectively, D < 6% in majority of samples) with those obtained by UV-VIS spectrophotometry. A borate/phosphate buffer of pH 9.0 (12.5mM borate and 12.5mM phosphate) containing 40mM sodium dodecylsulfate (SDS) was selected as an electrolyte for CE. A 50mM phosphate buffer and 5mM tetrabutylammonium hydroxide (TBAOH) water solution of pH 4.2 in 38% (v/v) acetonitrile were used as a mobile phase for isocratic HPLC separation on Sepharon SGX C18 (3 × 150 mm, 5 µm) column. RSDs for individual colorants were < 0.5% for migration times, < 3% for electrophoretic peak areas, < 0.9% for retention times and < 2.4% for HPLC peak areas. Limits of quantitations (LOQs for 10 S/N) were 1.5-3.3 mg/l for CE when using 50 µm I.D. separation capillary or 0.2 to 0.4 mg/l for HPLC. Keywords: synthetic dyes, wine, non-alcoholic drinks, liquid chromatography, capillary electrophoresis, spectrophotometry Journal: Czech Journal of Food Sciences Pages: 41-48 Volume: 18 Issue: 2 Year: 2000 DOI: 10.17221/8307-CJFS File-URL: http://cjfs.agriculturejournals.cz/doi/10.17221/8307-CJFS.html File-Format: text/html Handle: RePEc:caa:jnlcjf:v:18:y:2000:i:2:id:8307-CJFS Template-Type: ReDIF-Article 1.0 Author-Name: D.V. Nguyen Author-Name: M. Takácsová Author-Name: M.N. Dang Author-Name: K. Kristiánová Title: Antioxidant activities of allspice extracts in rapeseed oil Abstract: Spices are an important component of both commercial and homemade foods. Many spices have been shown to possess an antioxidant effect. In our study, we tested the activity of different allspice extracts (ethanol, chloroform, diethylether, benzene and hexane) on the stability of rapeseed oil. The order of antioxidant effectiveness was as follows: ethanol extract > chloroform extract> diethylether extract > benzene extract > hexane extract. The ethanol extract exhibited a remarkable antioxidant effect. Keywords: rapeseed oil, antioxidants, allspice, allspece extracts Journal: Czech Journal of Food Sciences Pages: 49-51 Volume: 18 Issue: 2 Year: 2000 DOI: 10.17221/8308-CJFS File-URL: http://cjfs.agriculturejournals.cz/doi/10.17221/8308-CJFS.html File-Format: text/html Handle: RePEc:caa:jnlcjf:v:18:y:2000:i:2:id:8308-CJFS Template-Type: ReDIF-Article 1.0 Author-Name: A. Hejtmánková Author-Name: V. Horák Author-Name: J. Dolejšková Author-Name: F. Louda Author-Name: H. Dragounová Title: Influence of yogurt cultures on benzoic acid content in yoghurt Abstract: Benzoic acid is not the natural metabolite in ruminants, therefore it is blocked in their gastrointestinal system in the form of benzoylglycine (hippuric acid). Change of hippuric acid into benzoic acid is realized by yoghurt cultures during yoghurt preparation. The influence of yoghurt cultures most frequented species J22, WV2, JK, T767 + T, J2, RX, JOB, WV3 and two strains MILCOM a. s. Laktoflora (used for preparation of yoghurt cultures) on benzoic acid level was tested on model yoghurts, produced from cow milk. One model of yoghurt was produced from goat milk, inoculated with yoghurt culture WV2. The levels of benzoic acid were determined by HPLC with SOP (standard operation procedure) used by the Czech Agricultural and Food Inspection. All experimental samples were prepared by the same technology and the same starting raw material and inoculated by the above 8 most frequently used yoghurt cultures. Differences between the used yoghurt cultures were found and statistically confirmed. Keywords: benzoic acid, yoghurt, yoghurt culture, strains, cow milk, goat milk, HPLC, hygienic limit Journal: Czech Journal of Food Sciences Pages: 52-54 Volume: 18 Issue: 2 Year: 2000 DOI: 10.17221/8309-CJFS File-URL: http://cjfs.agriculturejournals.cz/doi/10.17221/8309-CJFS.html File-Format: text/html Handle: RePEc:caa:jnlcjf:v:18:y:2000:i:2:id:8309-CJFS Template-Type: ReDIF-Article 1.0 Author-Name: B. Tremlová Title: Microscopic examination of products from fish meat Abstract: The paper deals with microscopic structure of commercial products from fish meat (ready-to-cook fish foods, meat products with an addition of fish meat). Samples were prepared by a histological technique, hematoxylin-eosin staining and differential staining to set off collagenic connective tissues (Calleja) and fish bones (modified van Gieson method) were used for microscopic examinations. Expected components and as declared on packages were confirmed by the results of microscopic examinations of ready-to-cook fish foods. The microscopic structure of meat products with an addition of fish meat was similar to that of traditional meat products of the same type. Fish bones of various size and at different quantity were detected in all products. Microscopic methods can be used to check the quality of products from fish meat with respect to the observation of technological procedures and technical standards. Keywords: histology, microscopy method, fish products Journal: Czech Journal of Food Sciences Pages: 55-60 Volume: 18 Issue: 2 Year: 2000 DOI: 10.17221/8310-CJFS File-URL: http://cjfs.agriculturejournals.cz/doi/10.17221/8310-CJFS.html File-Format: text/html Handle: RePEc:caa:jnlcjf:v:18:y:2000:i:2:id:8310-CJFS Template-Type: ReDIF-Article 1.0 Author-Name: M. Koreňovská Author-Name: O. Poláčeková Title: Trace elements content in virgin sunflower oil production Abstract: Trace elements content Cd, As, Hg, Pb, Ni, Cr, Fe, Cu, Zn, Co and Mn in the single steps of virgin sunflower oil production were studied. It was determined that mercury is cumulated in sunflower kernel and passes into oil. Chromium is concentrated in sunflower hulls and therefore is not passing into oil. Nickel, iron, copper, cobalt, manganese remained in pressed sunflower meal. Only their decreased content was found in oil because mechanical purifying (separation and filtration) minimized their content. We determined the levels of selected trace elements in sunflower virgin oils produced in Slovakia in 1995 and 1996. Methods of atomic absorption spectrometry using graphite furnace and flame were used. Keywords: trace elements, virgin sunflower oil, sunflower virgin oil production, atomic absorption spectrometry Journal: Czech Journal of Food Sciences Pages: 61-65 Volume: 18 Issue: 2 Year: 2000 DOI: 10.17221/8311-CJFS File-URL: http://cjfs.agriculturejournals.cz/doi/10.17221/8311-CJFS.html File-Format: text/html Handle: RePEc:caa:jnlcjf:v:18:y:2000:i:2:id:8311-CJFS Template-Type: ReDIF-Article 1.0 Author-Name: P. Novotná Author-Name: A. Landfeld Title: Colour of baked products during baking Abstract: The parameters of the colour of the surface of bakery products - brightness L*, a* for red and b* for yellow colour - were measured at different temperature regimes. The parameters were found to change during the time of baking. There is a considerable decrease in brightness L* and an increase in parameters a* and b* under the regime of temperature decrease between 6th and 10th minute of baking. The products baked at the 9th and 10th temperature grade were darker in general, brightness L* was lower for the 10th temperature grade and parameter a* was higher from the 8th minute of baking for the 9th temperature grade. Keywords: colour, baking Journal: Czech Journal of Food Sciences Pages: 67-70 Volume: 18 Issue: 2 Year: 2000 DOI: 10.17221/8312-CJFS File-URL: http://cjfs.agriculturejournals.cz/doi/10.17221/8312-CJFS.html File-Format: text/html Handle: RePEc:caa:jnlcjf:v:18:y:2000:i:2:id:8312-CJFS Template-Type: ReDIF-Article 1.0 Author-Name: J. Lachman Author-Name: M. Orsák Author-Name: V. Pivec Author-Name: J. Kučera Title: Effect of the year and storage on ascorbic acid content and total polyphenol content in three apple varieties Abstract: Ascorbic acid (AA) and total polyphenol content (TP) are important plant antioxidants with many healthy effects, such as "scavengers of free radicals", they inhibit oxidation of low-density lipoproteins, lower cholesterol levels, decrease fragility of blood vessels and increase their permeability, decrease heart coronary risk, etc. One of important sources of these compounds in human nutrition are apples. In two years (1997 and 1998) was investigated ascorbic acid content (AA) and total polyphenol content (TP) in three apple varieties (Idared, Gloster and Ontario) cultivated under equal conditions on the experimental plot of Czech University of Agriculture in Prague-Suchdol. AA content was determined by titration method with 2,6-dichlorphenolindophenol and TP content spectrophotometrically with Folin-Ciocalteau's reagent. In two years' trials AA and TP contents were estimated immediately after harvest in September and then monthly during storage for six months at +5°C. Statistically high significant differences were determined both in AA and TP contents during storage period - there was observed meaningful AA and TP decrease. The highest antioxidant content showed in both years early variety Ontario (in average 12.05 mg/kg AA, 2011.5 mg/kg TP), the lowest semi-early variety Gloster (in average 5.45 mg/kg AA, 1738.0 mg/kg TP). In this context the variety Ontario is the most favourable. The highest decrease of AA content was in variety Ontario (-30.05 %rel), the lowest in variety Gloster (-22.93 %rel ); in TP contents were differences negligible (-27.14 and -27.82 %rel). In spite of this decrease were in Ontario variety both values after six months storage the most favourable (8.45 mg/kg AA, 1466.5 mg/kg TP). Results were statistically evaluated with F-test and t-test. There could be seen differences among varieties and years of cultivation, but these differences were under the level of statistical significance showing only apparent tendencies. While varietal differences in decreasing of AA content during storage were greater (in interval from -22.93 %rel in Gloster variety to -30.05 %rel in Ontario variety), decreasing of TP contents during storage was nearly the same (about -27 %rel of original content Keywords: apples, antioxidants, polyphenols, ascorbic acid, effect of variety, effect of year of cultivation, changes during storage Journal: Czech Journal of Food Sciences Pages: 71-74 Volume: 18 Issue: 2 Year: 2000 DOI: 10.17221/8313-CJFS File-URL: http://cjfs.agriculturejournals.cz/doi/10.17221/8313-CJFS.html File-Format: text/html Handle: RePEc:caa:jnlcjf:v:18:y:2000:i:2:id:8313-CJFS Template-Type: ReDIF-Article 1.0 Author-Name: J. Pátková Author-Name: D. Šmogrovičová Author-Name: Z. Dömény Author-Name: P. Bafrncová Title: Strains for fermentation of high gravity worts - a review Abstract: The paper deals with isolation and construction of new strains usable for fermentation of high gravity worts. These worts cause stress for yeasts, and influence their metabolism and fermentation activity. It is reflected in fermentation speed and beer quality. Brewers' yeast with STA2 genome for production of extracellular glucoamylase was obtained by gene manipulations, which is also used in industrial production. Operational experiments were successfully conducted with new strains of yeasts with these characteristics: ethanol-tolerant, osmotolerant, not glucose-repressed, higher flocculation capacity, ability to degrade turbidity-forming substances, influenced production of flavouring substances, but their larger-scale use is prevented by legislation. Keywords: brewers' yeasts, gene manipulations, HG, VHG, stress Journal: Czech Journal of Food Sciences Pages: 75-80 Volume: 18 Issue: 2 Year: 2000 DOI: 10.17221/8314-CJFS File-URL: http://cjfs.agriculturejournals.cz/doi/10.17221/8314-CJFS.html File-Format: text/html Handle: RePEc:caa:jnlcjf:v:18:y:2000:i:2:id:8314-CJFS