Retrogradation of partially gelatinised potato starch prepared by ball milling

This study was performed to evaluate the effect of partial gelatinisation on the retrogradation of modified potato starch. The partially gelatinised starches with gelatinisation degree at mean levels of 22.47%, 49.18%, 76.80% and 86.19% were prepared by ball milling (0.5, 1.5, 3 and 10h). The thermal properties and crystal structure of retrograded starch were examined during 21days of refrigerated storage at 4 degrees C. Retrograded starch with high initial gelatinisation degree (86.19%) showed higher retrogradation enthalpy of 6.12 +/- 0.18Jg(-1) and lower onset temperature of 45.41 +/- 0.24 degrees C than sample with low gelatinisation degree (22.47%) where the results were 1.32 +/- 0.18Jg(-1) and 54.05 +/- 0.03 degrees C, respectively. During storage, two peaks in the X-ray diffractograms for starch with high gelatinisation degree appeared and increased rapidly, while the peaks for starch with low gelatinisation degree increased slowly. These results suggest that a certain amount of remainder crystals presented in partially gelatinised starch impeded the retrogradation.