Czech Journal of Food Sciences, 2001 (vol. 19), issue 4
Changes in some microbiological and chemical parameters during the ripening of sheep cheese at different temperatures
J. Pažáková, M. Pipová, P. Turek, J. Nagy
Czech J. Food Sci., 2001, 19(4):121-124 | DOI: 10.17221/6594-CJFS 
The changes in microbiological and chemical parameters during the fermentation and ripening of sheep cheese were observed. The cheese was produced from raw sheep's milk at different temperatures on the sheep farm. The following parameters were determined: total plate count, coliform count, Staphylococcus aureus count, pH value, titrimetric acidity, and the amount of lactic acid. As our results indicate, the fermentation at temperatures of between 18-22°C reduces the number of undesirable micro-organisms due to the presence of lactic acid being produced by lactic-acid bacteria. During the fermentation at lower temperatures (below 18°C) the...
Assay of antibiotic detection limits in cow's milk model samples and comparison of sensitivity of various detection systems (disk diffusion method, Delvotest SP and Penzym S 100).
B. Hozová, M. Kratmüllerová
Czech J. Food Sci., 2001, 19(4):125-131 | DOI: 10.17221/6595-CJFS
The work was aimed at estimating the detection limits of 21 antibiotics (beta-lactam antibiotics, cephalosporins, aminoglycosides, macrolides and others) by means of three types of detection systems (disk diffusion method with Bacillus stearothermophilus var. calidolactis C 953, Delvotest SP and Penzym S 100) and to verify their sensitivity in the evaluation of the admissible maximum residual limits (MRL). The high sensitivity and the good correlation of results have been achieved mainly by applying the rapid methods such as Delvotest SP and Penzym S 100 versus the less sensitive disk diffusion method. In the next stage of the work,...
The determination of isoflavones and coumestrol by capillary electrophoresis
J. Moravcová, T. Kleinová
Czech J. Food Sci., 2001, 19(4):132-138 | DOI: 10.17221/6596-CJFS
The separation of six isoflavones (biochanin A, isoformononetin, formononetin, prunetin, daidzein and genistein) and coumestrol on an uncoated fused-silica capillary electrophoresis column was optimised using alkaline borate buffer as electrolyte and DAD detection. A baseline separation of all analytes except a pair, formononetin-biochanin A was achieved at pH 10.5 in 25 min. Detection limits were low (0.1 µg/ml) and the linearity of the detector response was established in the concentration range 0.4-60 µg/ml (180 µg/ml for coumestrol). Coumestrol was synthesized and the carbon signals in 13C-NMR spectrum of both coumestrol and di-O-acetylcoumestrol...
Antioxidant activity of phenolic fraction of pea (Pisum sativum)
R. Amarowicz, M. Karamać, S. Weidner
Czech J. Food Sci., 2001, 19(4):139-142 | DOI: 10.17221/6597-CJFS
An extract of seeds of pea was prepared using 80% (v/v) acetone. Six fractions (I-VI) were separated from the crude extract on a Sephadex LH-20 column using methanol as the mobile phase. The antioxidant activity of fractions was investigated in a β-carotene-linoleate model system. For individual fractions, UV spectra were recorded and the content of total phenolics was determined. Results of the β-carotene-linoleate model system indicated that antioxidant activities of separated fractions correlated with their content of total phenolic compounds and they decreased in the order of IV = VI > V > III > I > II. The antioxidant activity...
The determination of ferulic acid in sugar beet pulp
P. Jankovská, J. Čopíková, A. Sinitsya
Czech J. Food Sci., 2001, 19(4):143-147 | DOI: 10.17221/6598-CJFS
The content of ferulic acid in sugar beet pulp was determined by reverse phase high-pressure liquid chromatography (HPLC) and UV/VIS-spectroscopy. The acid extracts of pectin carrying feruloyl groups were prepared for analysis. To release ferulic acid from pectin the hydrolysis in alkaline medium (pH = 12.5) was performed. Both non-hydrolysed and hydrolysed extracts were measured by UV/VIS-spectroscopy after pH adjustment to the value of 10. The absorbance maximum was observed at 372 nm (ester of ferulic acid) for non-hydrolysed extracts and at 345 nm (sodium ferulate) for hydrolysed extracts. The HPLC estimation of ferulic acid was made in hydrolysed...
Use of helical ribbon mixer for measurement of rheological properties of fruit pulps
P. Novotná, A. Landfeld, K. Kýhos, M. Houška, J. Strohalm
Czech J. Food Sci., 2001, 19(4):148-153 | DOI: 10.17221/6599-CJFS
Fruit pulps contain fine particles of the flesh of the original fruit that are suspended in the fruit juice. This suspension has a tendency to settling or separation during measurements of its rheological properties in the rotational rheometer with coaxial cylinders (especially if the greater gap is used). In this case the use of a mixer is convenient. The mixer can serve as a tool for measurement of rheological properties and at the same time it can prevent the settling and it is not sensitive to the occurrence of greater particles in the measured fluid. The helical ribbon mixer was used in this work for measurement of five samples of fruit pulp....
Food preferences and choice among the Polish students
E. Babicz-Zielińska
Czech J. Food Sci., 2001, 19(4):154-160 | DOI: 10.17221/6600-CJFS
The ratings and rankings of some, mainly product-related and consumer-related factors influencing the choice of different groups of food - vegetables, fruit, dairy products, spreads, and frying and baking fats - were evaluated among 448 Polish students. Freshness, taste and health value appeared the most important choice factors in vegetables, fruit, and spreads; freshness, taste and quality in dairy products; freshness, health value and durability in frying and baking fats. Advertising was the least important factor among all factors considered for all groups of products. The significant influences of sex on ratings of choice factors were observed....