Influence of acetic anhydride on physicochemical, morphological and thermal properties of corn and potato starch

The physicochemical, morphological, thermal and rheological properties of acetylated corn and potato starches, prepared using acetic anhydride at different levels (4–12 g), were compared. Corn starch showed lower acetyl (%) and degree of substitution (DS) than potato starches under similar experimental conditions. The acetylated corn and potato starches showed slightly higher amylose contents than their counterpart native starches. Acetylated starches showed higher swelling power, solubility and light transmittance than native starches, which subsequently increased with the increase in acetic anhydride concentration in the reaction medium. The extent of change in these properties, as a function of acetic anhydride concentration, was significantly higher in potato than corn starches. Both potato and corn starches were fused after conversion to acetylated starches; however, this effect was more pronounced in the former under similar reaction conditions. The syneresis (%) of both acetylated and native starches increased during storage at 4 °C; however, the increase was less pronounced in acetylated starches.