Structural enhancement leading to retardation of in vitro digestion of rice dough in the presence of alginate

The effect of alginate with distinct content of guluronate sequences on the structural properties and in vitro digestion of rice dough has been investigated. Materials were engineered to serve as a model system of instant soup-based rice noodles available in the market. Alginate set externally with calcium within the dough matrix reduced cooking loss and soluble starch leakage following boiling of preparations. Small-deformation dynamic-oscillation monitored the structural properties of alginate networks, which were capable of supporting the starch granules in a cohesive composite gel. Scanning electron microscopy afforded tangible evidence of the dramatic effect of the polysaccharide network on the morphology of rice dough. Fourier transform infrared spectroscopy probed at the molecular lever the efficiency of external setting to deliver calcium ions at the vicinity of the carboxyl groups of the alginate chain. It appears that the continuous alginate phase encapsulates starch granules thus retarding in vitro digestion of the rice dough. Results are promising for the development of commercial rice noodles with superior appearance, textural profile and digestibility. (C) 2008 Elsevier Ltd. All Fights reserved.