Research On Preparation And Properties Of The Cassava Crosslinking-Oxidized Starch

Cassava starch is abundant in Guangxi. Crosslinking-oxidized starch was prepared with sodium trimetaphosphate as crosslinking agent, hydrogen peroxide as oxidizer and cassava starch by microwave treatment and semi-dry process. The synthesis routes, process models and properties were investigated, which can provide some valuable parameters for its further application.Two synthesis routes were studied: oxidization first or cross linking first. The results illustrated the optimum synthesis way was cross linking first .That is, starch was cross linked first with sodium trimetaphosophate then oxidized with hydrogen peroxide and CuSO₄ as catalysis. The reaction conditions were optimized by the way of single factor and orthogonal experiments. And the mathematical reaction model was studied with the linear regressive equation of orthogonal experiment, the results of which indicate the relationship between experiment factors and carboxyl content ,viscosity, transparency can be described by simple equation. The optimum synthesis conditions for crosslinking-oxidized starch also were studied. The optimum cross linking conditions were: microwave power 180W, pH10, reaction time 3min, water/starch (weight) 30%, cross-linking agent/starch (weight) 0.5%. The optimum catalytic oxidation conditions were: microwave power 180W, pH 7, starch: CuSO₄: H₂O₂: H₂O (weight) =100:0.06:10:30, then carboxyl content could reach 0.9% when reaction had begun for 3 minutes.The structure of crosslinking-oxidized starch was investigated with examination of FTIR. And paste viscosity, transparency, retrogradation, anti-ageing property, shear resistance, freeze-defrost stability and film forming ability were studied. The results indicate that the crosslinking-oxidized cassava starch has the advantages of both cross-linking starch and oxidized starch, and is more adaptive to the development of food industry.