Properties of Cast Films Made of HCl‐Methanol Modified Corn Starch

Abstract

Abstract The molecular and physicochemical properties of the studied starches modified with 0.36% HCl in methanol at 25 °C and 45 °C were related to the film properties of these starches. The weight‐averaged molecular weight ( M w ) and the number of long‐chain branches (DP 13‐36) of HCl‐methanol modified starch decreased with increasing degree of acid modification, but the number of short‐chain branches (DP < 6) increased. HCl‐methanol modification significantly decreased the ghost formation in gelatinized starch dispersions and the viscosity of starch film‐forming dispersions. Thus, the homogeneity of the produced starch films was improved and their opacity reduced. Proper HCl‐methanol modification produced corn starch films with lower moisture absorption rate and maximum moisture content under high relative humidity (RH = 97%) condition.