Thermostructural behavior of red cochineal dye stabilized with sucrose and embedded in a silica xerogel matrix

This work deals with the carminic acid stabilization in a silica matrix and the study of structural properties. Results indicate that silica provides exceptional thermal stability to the carminic dye because its functional properties remain without significant changes up to 500 degrees C. The embedded carminic acid changes the crystallization behavior of silica. The carminic acid extracted from Mexican cochineal was firstly stabilized with sucrose and after embedded in a silica matrix using the sol-gel method. The structural behavior was analyzed in function of temperature from RT to 900 degrees C. The resulting properties were studied using X-ray diffraction and FT-IR spectroscopy. Interaction of carminic acid with silica reduces the formation temperature of tridymite and cristobalite. Amorphous tridymite was detected at 400 degrees C, semicrystalline tridymite at 700 degrees C, alpha-cristobalite at 800 degrees C, and beta-cristobalite at 900 degrees C. The improved stability of carminic acid results from its interaction with the silica, which also modifies the silica crystallization kinetics.