Physical characterization of arabinoxylan powder and its hydrogel containing a methyl xanthine

Arabinoxylan powder has been characterized using TGA, FT-IR, MTDSC, SEM and particle size analysis. Results showed that particle size distribution was bimodal with peaks at 61 mu m and 599 mu m. Particles were irregular in shape and surface. Thermal analysis revealed an endothermic event at 70.9 degrees C due to water loss followed by the glass transition temperature at 198.8 degrees C. The decomposition temperature was detected at 303 degrees C. Arabinoxylan hydrogels including caffeine were prepared by peroxidase/peroxide oxidative cross-linking. The mechanical properties determined at various content of peroxidase showed the force at failure, the deformation at failure and the cohesiveness to decrease slightly for peroxidase concentration greater than 264 mu g/g (polysaccharide basis). The hydrogels swelling was greater in distilled water than in 0.1 M HCl after 3 h. The caffeine release was the greatest in acidic pH. The dissolution profiles were modelled using the Higuchi, Ritger and Peppas and Peppas and Sahlin equations to explain the mechanism of drug release. (C) 2011 Elsevier Ltd. All rights reserved.