Synthesis and Evaluation of Microstructure of Phosphorylated Chestnut Starch

Phosphorylated chestnut starch was produced by a semidry process, in which chestnut starch and sodium dihydrogen phosphate dihydrate ( NaH 2 PO 4 ·2H 2 O ) were used as a raw material and an esterifying agent, respectively. Single‐factor test and response surface analysis were performed in this study. The optimized synthesis of phosphorylated chestnut starch and its microstructure were studied. The optimum preparation conditions were listed as follows: NaH 2 PO 4 ·2H 2 O concentration of 7%, reaction temperature of 146C, reaction time of 140 min and pH 6. The average experimental apparent viscosity under the optimum conditions was found to be 33.69 ± 0.33 Pa·s, with an increase of 208.99% higher than that of native chestnut starch. Fourier transform infrared spectrum analysis revealed that some of hydroxyl groups were replaced by phosphate groups during phosphorylation. Scanning electron microscopy showed that a part of the modified chestnut starch granules sagged and revealed damaged traces. X ‐ray diffraction analysis indicated that the crystalline type of phosphorylated chestnut starch was type C. The crystalline area was slightly damaged and esterification mainly occurred in the amorphous area of starch molecules. Practical Applications Phosphorylated starch has much more transparent starch paste, better stability and higher water retention compared with the native starch, and phosphorylated starch can be widely used in various fields of the industrial production. However, there is little information on the preparation process and physicochemical properties of phosphorylated chestnut starch till now. In the present study, B ox– B ehnken design as well as canonical and ridge analyses were used to optimize these process parameters of phosphorylated chestnut starch, and its microstructure were studied. The results of this study showed that response surface methodology proved to be fairly accurate in predictive modeling and optimization of conditions for the synthesis of phosphorylated chestnut starch. Optimization of process could be considered as a sustainable alternative method to achieve simplified handling and improve the quantity of targeted products. We believe that starch industry can utilize the results of this study in their applications.