Effect of propylation on the characteristics of corn starch and variation of properties with different degrees of substitution



Corn starch was modified by propylation with different degree of substitution (DS). DS of four starch modifications were 0.61, 1.56, 2.27, and 2.51. Samples were characterized by FTIR, XRD, TG-DTA, swelling power, solubility, water binding capacity, and light transmittance. Results of the systematic physico-chemical characterization of the starch modification in comparison with the native starch have been documented in the article. Results showed that during propylation, the crystalline structure of starch got destroyed and surface of the starch was eroded. Propylated starch (DS 2.51) showed 85% weight loss at temperatures from 300 to 400°C, whereas the native starch underwent similar weight loss (83%) from 250 to 300°C. Swelling power and water binding capacity of native starch (DS 0.0) were 3.09 g/g and 89.8%, respectively. However, in propylated starch at low DS (DS 0.61), swelling power and water binding capacity increased to 10.55 g/g and 136.8% under same conditions. At high DS (DS 2.51), swelling power was similar to native starch at 65°C, whereas solubility and water binding capacity decreased to below that of native starch. Light transmittance of propylated starch with high DS (DS 2.51) increased dramatically compared with native starch. Propylation improved the hydrophobic transformation and thermal stability of starch at high DS. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011