Thermostability and structural evolution of silica xerogel matrix with embedded carrot juice

Abstract

Thermal stabilization of carrot juice components, mainly β-carotene, has been studied when they are embedded in a silica matrix. The organic components induce structural changes on the inorganic matrix, decreasing the sintering temperature at which stable forms of amorphous silica such as β-tridymite, and crystalline structures like α / β-cristobalite can be obtained, they also induce the formation of stishovite traces at ambient pressure. We made use of the sol-gel method with a water/TEOS molar ratio of 11 to prepare the silica composite. The characterization of the samples was carried out using X-ray diffraction, IR spectroscopy, emission fluorescence, thermogravimetric analysis and scanning electron microscopy. Results indicate high thermostability of the composite as a result of the protective function of the photosystem II carotenoids, which tend to delay the gel-glass transition removing water at higher temperature than other chlorophyll species embedded in a silica matrix.