Properties of Starch-Sugar-Water Systems Studied by Dynamic rheological Measurements

anglais. Saturated aqueous solutions of D-glucose, D-fructose and sucrose were blended with solid granules of corn, waxy corn and tapioca starches. Systems deficient in water were obtained, properties of which were studied by dynamic rheological measurements. The properties of systems obtained at different proportions of saturated sugar solutions to starch were characterized. It was concluded that desired rheological properties (fluidity of blends) can be achieved by adjusting relevant quantity of plasticizers (different sugars and water). Similarly, by adjusting the quality and quantity of plasticizers, the phenomenon of “magic trick” (viscoelastic behaviour) can be achieved in the studied systems, however, that property is manifested in a very narrow range of starch-to-saturated sugar solution ratio. For all systems under study, the quantity of saturated solutions of relevant sugars, needed to achieve plasticity of each systems, was depicted. It was also concluded that in order to achieve plasticity with tapioca starch granules, for each 2 g of this starch 1.83 and 1.99 g of saturated solution of D-glucose and sucrose, respectively, are needed. In order to achieve plasticity with granules of waxy corn starch - 2.63 and 2.35 g, respectively, and with granules of corn starch - 3.09 and 2.5 g of saturated solutions of D-glucose and sucrose, respectively, are needed. The systems containing saturated solutions of D-fructose have different relationships. In order to achieve plasticity of blends containing corn, waxy corn and tapioca starch, for each 2 g of starch 2.14; 2.13 and 2.33 g, respectively, of saturated fructose solution is needed.

anglais. starch granules, D-glucose, D-fructose, sucrose, competition for water molecules, viscoelastic behaviour, plasticity, complex viscosity, storage and loss moduli, loss factor

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