Gelatinization transitions of acid-modified tapioca starches by Differential Scanning calorimetry (DSC)

Tapioca starch was partially hydrolyzed by 6% and 12% hydrochloric acid (w/v) at room temperature for various length of time. The gelatinization transitions of the acid-modified tapioca starches were studied using Differential Scanning Calorimetry. Starch suspensions (67% moisture) were heated at 5 °C/min to follow melting transition of amylopectin. As the hydrolysis time increased, onset (T o ), peak (T p ) and conclusion (T c ) temperatures of gelatinization have been observed to increase, in the same order of relative crystallinity, until reaching some critical values, then decreased with the large broadening of the endotherms. The increasing of the transition temperatures corresponded to the retrogradation of the remaining partially hydrolyzed amylose followed by a decrease of these parameters corresponding to the reduction of the length of the chains of double helices amylopectin.