Artículos de revistas
Thermal degradation kinetics of bixin in an aqueous model system
Registro en:
Journal Of Agricultural And Food Chemistry. Amer Chemical Soc, v. 53, n. 6, n. 2307, n. 2311, 2005.
0021-8561
WOS:000227736100070
10.1021/jf0481655
Autor
Rios, AD
Borsarelli, CD
Mercadante, AZ
Institución
Resumen
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 OF 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 (E-a approximate to 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. 53 6 2307 2311