Czech Journal of Food Sciences, 2000 (vol. 18), issue 2
Capillary electrophoretic and liquid chromatographic determination of synthetic dyes in non-alcoholic drinks and wine samplesOriginal Paper
I. Jančářová, A. Vondráčková, A. Šlampová, V. Kubáň
Czech J. Food Sci., 2000, 18(2):41-48 | DOI: 10.17221/8307-CJFS 
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...
Antioxidant activities of allspice extracts in rapeseed oilOriginal Paper
Nguyen D.V., M. Takácsová, M.N. Dang, K. Kristiánová
Czech J. Food Sci., 2000, 18(2):49-51 | DOI: 10.17221/8308-CJFS
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.
Influence of yogurt cultures on benzoic acid content in yoghurtOriginal Paper
A. Hejtmánková, V. Horák, J. Dolejšková, F. Louda, H. Dragounová
Czech J. Food Sci., 2000, 18(2):52-54 | DOI: 10.17221/8309-CJFS
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...
Microscopic examination of products from fish meatOriginal Paper
B. Tremlová
Czech J. Food Sci., 2000, 18(2):55-60 | DOI: 10.17221/8310-CJFS
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...
Trace elements content in virgin sunflower oil productionOriginal Paper
M. Koreňovská, O. Poláčeková
Czech J. Food Sci., 2000, 18(2):61-65 | DOI: 10.17221/8311-CJFS
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...
Colour of baked products during bakingOriginal Paper
P. Novotná, A. Landfeld
Czech J. Food Sci., 2000, 18(2):67-70 | DOI: 10.17221/8312-CJFS
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.
Effect of the year and storage on ascorbic acid content and total polyphenol content in three apple varietiesShort Communication
J. Lachman, M. Orsák, V. Pivec, J. Kučera
Czech J. Food Sci., 2000, 18(2):71-74 | DOI: 10.17221/8313-CJFS
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...
Strains for fermentation of high gravity worts - a reviewReview
J. Pátková, D. Šmogrovičová, Z. Dömény, P. Bafrncová
Czech J. Food Sci., 2000, 18(2):75-80 | DOI: 10.17221/8314-CJFS
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...