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Isotopic characterization of selected fruit juices - determination of authenticity on the basis of deuterium content by SNIF-NMR
Vyčítalová, Lucie ; Kolář, Kamil (referee) ; Sečkářová,, Pavlína (advisor)
The deuterium content of sugar in fruits is influenced mainly by two factors – the botanical and also the geographical origin of the fruit. The information of the fruit origin is kept even after fermentation of the sugar, in the molecules of ethanol. The deuterium content on the methyl group of ethanol then varies depending upon the botanical origin of the fruit. SNIF-NMR (Site-specific Natural Isotope Fractionation – Nuclear Magnetic Resonance) is a specific method for determination of the deuterium isotopic ratio (D/H) in small molecules, e.g. ethanol. This isotopic technique is widely used for determination of sugar adulteration of fruit-based beverages (wines, fruit juices..). In this thesis, the authentic samples of five different fruits (apples, oranges, grapefruits, pineapples and grapes) available in the Czech market have been collected and analyzed by SNIF-NMR. The results are presented as well as the comparison to some commercially available fruit juices and nectars.
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Analytické a senzorické možnosti kontroly falšování pravosti révového vína
Rozek, Kamil
The diploma thesis deals with analytical and sensorial possibilities of control of grape wine adulteration. In the first, theoretical part of the thesis, the author introduces valid legislation regulating authorized substances in wine, as well as the wine production processes itself. The reader is acquainted with the means of wine adulteration in the Czech Republic that ensued from an analysis of unsatisfactory samples of wine, collected between 2012 -- 2015 by the SZPI (Czech Agriculture and Food Inspection Authority). The second, practical part of the thesis, describes not only grape wine and SZPI samples imitation production processes, but also methods used for their subsequent sensorial and analytical study. Besides, it interprets measured data, and compares and contrasts the possibilities and appropriateness of the sensorial evaluation and analytical study for the detection of wine adulteration.
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Isotopic characterization of selected fruit juices - determination of authenticity on the basis of deuterium content by SNIF-NMR
Vyčítalová, Lucie ; Kolář, Kamil (referee) ; Sečkářová,, Pavlína (advisor)
The deuterium content of sugar in fruits is influenced mainly by two factors – the botanical and also the geographical origin of the fruit. The information of the fruit origin is kept even after fermentation of the sugar, in the molecules of ethanol. The deuterium content on the methyl group of ethanol then varies depending upon the botanical origin of the fruit. SNIF-NMR (Site-specific Natural Isotope Fractionation – Nuclear Magnetic Resonance) is a specific method for determination of the deuterium isotopic ratio (D/H) in small molecules, e.g. ethanol. This isotopic technique is widely used for determination of sugar adulteration of fruit-based beverages (wines, fruit juices..). In this thesis, the authentic samples of five different fruits (apples, oranges, grapefruits, pineapples and grapes) available in the Czech market have been collected and analyzed by SNIF-NMR. The results are presented as well as the comparison to some commercially available fruit juices and nectars.
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