Czech Journal of Food Sciences, 2007 (vol. 25), issue 1

Biosynthesis of food constituents: Vitamins. 1. Fat-soluble vitamins - a review

Jan Velíšek, Karel Cejpek

Czech J. Food Sci., 2007, 25(1):1-16 | DOI: 10.17221/736-CJFS  

This review article gives a survey of the generally accepted biosynthetic pathways that lead to fat-soluble vitamins (vitamin A, vitamin D, vitamin E, vitamin K, the corresponding provitamins, and the closely related ubiquinones and plastoquinones) in animals, plants, and microorganisms. Extensively used are reaction schemes, sequences, and mechanisms with the enzymes involved, with detailed explanations using chemical principles and mechanisms.

Determination of banned dyes in spices by liquid chromatography-mass spectrometry

Petr Botek, Jan Poustka, Jana Hajšlová

Czech J. Food Sci., 2007, 25(1):17-24 | DOI: 10.17221/737-CJFS  

A simple and rapid multiresidue method for the determination of nine banned synthetic dyes in various spices has been developed. Reversed phase HPLC coupled with mass spectrometry (tandem in time-ion trap mass analyser) was employed for the examination of crude acetonitrile extract acidified with acetic acid. The detection limits of Para Red, Sudan Orange G, Sudan I, Sudan II, Sudan III, Sudan IV, Sudan Red 7B and Rhodamine B were in the range of 0.02-0.1 mg/kg, the recoveries ranged from 75.7-92.3% with repeatability of 0.9-11.3%. Rather worse performance characteristics were obtained with Tropaeolin 000, obviously due to its more polar nature as...

Determination of polydextrose as a fat replacer in butter

Kateřina Míčková, Jana Čopíková, Andriy Synytsya

Czech J. Food Sci., 2007, 25(1):25-31 | DOI: 10.17221/738-CJFS  

Polydextrose is used in several countries as a low caloric sugar and fat substitute (bulking agent). It is prepared by condensation of glucose, D-glucitol, and citric acid (89:10:1). The resulting condensation product has no chemically defined structure but it represents a mixture of polymerisation products. The determination of polydextrose in butter is complicated owing to a large excess of fats and to the presence of other compounds, mainly proteins. FT-IR spectroscopy seems to be a satisfying method for the detection of polydextrose in samples derived from food products. The presence of polydextrose in butter was verified after the removal of fats...

Sodium cholate sorption on N-octadecylpectinamide in comparison with cholestyramine

Andriy Synytsya, Lucie Fesslová, Milan Marounek, Jana Čopíková

Czech J. Food Sci., 2007, 25(1):32-38 | DOI: 10.17221/739-CJFS  

N-Octadecylpectinamide is hydrophobically modified HM citrus pectin. Previously, it had been prepared by heterogeneous amino-de-alkoxylation of initial pectin with n-octadecylamine in dimethylsulphoxide and characterised as potential hydrophobic sorbent and cholesterol lowering agent. The sorption properties of N-octadecylpectinamide were analysed in comparison with cholestyramine, an effective bile acid sequestrant. Sorption experiments were carried out using sodium cholate as a model bile acid. Cholate concentration was estimated by enzymatic spectroscopic method. Sorption kinetics curves and sorption isotherms of both sorbents...

Free and bound 3-chloropropane-1,2-diol in coffee surrogates and malts

Veronika Divinová, Marek Doležal, Jan Velíšek

Czech J. Food Sci., 2007, 25(1):39-47 | DOI: 10.17221/735-CJFS  

The levels are reported of the free 3-chloropropane-1,2-diol (3-MCPD), its bound forms, the recognised precursors of 3-MCPD, and the factors influencing its formation in 5 selected coffee surrogates and 18 malts in the Czech Republic. The coffee surrogates had the free 3-MCPD level in the range of < 9.0 to 32 µg/kg while the highest amount was found in roasted barley. In malts, the free 3-MCPD levels were similarly low (< 9.0 to 45 µg/kg) being the highest in roasted malts (16-45 µg/kg). Nevertheless, the values found in either surrogates or malts, calculated after normalisation to 40% dry matter content, did not exceed the...