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Analyse des caramels liquides : développement et validation de nouvelles méthodes basées sur la chromatographie en phase liquide bidimensionnelle (LC-LC)

Abstract : Caramel liquid, obtained by heat treatment of sugars, is commonly used to alter the taste or colour of food products.Among promoters of caramelization allowed, ammonia (for caramel colours of class III) and ammonium salts (for those of class IV) are a source of neoformed contaminants (NFC) such as 2-acetyl-4-(1,2,3,4-tetrahydroxybutyl)imidazole (THI), immunosuppressive agent, and 4-methylimidazole (4MeI), convulsive agent. These molecules have contents limited by the European regulations to 10 and 250 ppm, respectively.To improve knowledge of the chemistry of caramel and quality of caramel colours by controlling the formation of NFC, it is necessary to develop analytical methods that are both reliable, fast and easy to implement. This thesis presents the development and validation of new methods based on two-dimensional liquid chromatography (LC-LC). These very selective methods can minimize analysis time since sample preparation is reduced to a simple dilution with water and the two consecutive chromatographic separations are performed on a fully automated system. The method validation by the accuracy profiles allowed to show that 90 % of obtained results correspond to the agreement value more or less 20 %, in the field of concentration 10 to 50 ppm for THI, 20 to 500 ppm for 4MeI, 200 to 2500 ppm for fructose, sucrose, lactose, maltose and maltotriose and 500 to 2500 ppm for glucose.These methods are finally applied to monitor the reaction of caramelization and to control the quality of finished products.
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Cédric Moretton. Analyse des caramels liquides : développement et validation de nouvelles méthodes basées sur la chromatographie en phase liquide bidimensionnelle (LC-LC). Autre. Université Claude Bernard - Lyon I, 2009. Français. ⟨NNT : 2009LYO10279⟩. ⟨tel-00675449⟩

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