Please use this identifier to cite or link to this item: http://repositorio.unicamp.br/jspui/handle/REPOSIP/196623
Type: Artigo de periódico
Title: Thermal Degradation Kinetics Of Bixin In An Aqueous Model System.
Author: Rios, Alessandro de O
Borsarelli, Claudio D
Mercadante, Adriana Z
Abstract: The kinetics of the thermal degradation of the natural cis carotenoid bixin in a water/ethanol (8:2) solution was studied as a function of temperature (70-125 degrees C), using high-performance liquid chromatography. The curves for the decay of bixin and formation of products (e.g., di-cis and all-trans isomers and a C17 degradation compound) did not adjust well to a first-order rate law, but very good fits were obtained using a biexponential model. This mathematical modeling gave the rate constant values for the formation of the primary products from bixin, and the energy barrier for each step was obtained. The di-cis isomers were formed immediately (15 kcal/mol) together with the decay of bixin, followed by a slow consumption, indicating their role as reaction intermediates. In fact, the di-cis isomers could easily revert to bixin (Ea approximately 3 kcal/mol) or yield the primary C17 degradation product, with an energy barrier of 6.5 kcal/mol. In turn, 24 kcal/mol was necessary for the Bix --> all-trans step, explaining its slower formation.
Subject: Carotenoids
Chromatography, High Pressure Liquid
Hot Temperature
Kinetics
Mathematics
Models, Chemical
Spectrophotometry
Thermodynamics
Water
Rights: fechado
Identifier DOI: 10.1021/jf0481655
Address: http://www.ncbi.nlm.nih.gov/pubmed/15769172
Date Issue: 2005
Appears in Collections:Artigos e Materiais de Revistas Científicas - Unicamp

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