Effect of longer heating time on depolymerization of low moisturized starches

Low moisturized potato, sweet potato, corn and wheat starches were treated with a flow tester under heated and heated-sheared conditions. The starches depolymerized into lower molecule by longer heating time at 150°C. With an increase in heating time, the cold water solubility of starches increased and the degree of depolymerization progressed. Comparing heated treatment with longer heating time and heated-sheared treatment, 60-120min heating was necessary for heated specimens to obtain similar cold water solubility and degree of depolymerization of heated-sheared specimens. These results conducted that heated-sheared treatment strongly promoted the depolymerization of low moist starches under high temperature as compared with heated treatment only. From the results of λ_max of iodine-polysaccharide complex, there was almost same molecular state between heated for longer time and heated-sheared treatment. Both amylose and amylopectin depolymerized into lower molecule by both treatments.