Abstract: Corn starch-water suspension(5%, W/V) was subjected to high pressure treatment at 500, 550, 600, 650 MPa for 5 mim, The samples were dried after 0, 3, 5, 10 days respectively. X-ray diffraction was used to determine. The results showed that to a certain extent crystallinity of the sample treated by ultra high pressure after annealing in low temperature increase. After 3 days storage, a maximum retrogradation extent in the UHT-treated starches at 500 MPa is obtained while there are no changes in crystalline type. The same also happened to the UHT-treated starches at 550 MPa, but retrogradation for more long time could cause the variation in crystalline type. The UHT-starches at 600 and 650 MPa are storied for a period of time, there are increase of crystallinity and the crystalline type chang from A to B.

Key words: ultra high pressure, starch, retrogradation