Study on the Thermal Properties and Retrogradation Mechanism of Sweet Potato Starch

The retrogradation of sweet potato starch under different moisture contents,final temperatures for gelatinization,cooling rates and holding temperatures were investigated using Differential Scanning Calorimetry.The result illuminated that under such conditions as 70% of moisture content and above 90 ℃,amylose in sweet potato starch leached out of starch granules,then congregated to form a larger ordered crystalline area,and formed amylose-lipid complexes,which form helices when cooling.The ice-crystal baffled the congregation of exterior chains in amylopectin and the re-arranging of amylose when sweet potato starch paste was stored under the range of 0 ℃~-4 ℃.The rate of crystal growth was slow and the degree of retrogradation was largest when storage temperature ascended to about 4 ℃.The retrogradation was increased by a slower cooling rate.