Optimization of Preparation of Corn Starch Phosphates of High Thermal Viscosity by Response Surface Methodology

The preparation of corn starch phosphates which possess height thermal viscosity was optimized in this study. A central composite design of response surface methodology involving phosphate (sodium dihydrogen phosphate and disodium hydrogen phosphate) concentration, ratio of sodium dihydrogen phosphate and disodium hydrogen phosphate, phosphorylation temperature and urea concentration was used, and second-order model for thermal viscosity was employed to generate the response surface. The optimum condition for preparation of corn starch phosphates of high thermal viscosity was as follows: phosphate concentration 4.94%; ratio of sodium dihydrogen phosphate and disodium hydrogen 0.80, phosphorylation temperature 145°C; urea concentration 5.5%. The predicted value for thermal viscosity of corn starch phosphates at the optimum condition was 7652 cP. Experimental verification gave value of 7550±25 cP.