The retrogradation characteristic of sweet potato and maize amylopectin prepared by retrogradation

Sweet potato and maize amylopectin were prepared from their native starches by the method of retrogradation, and the retrogradation characteristics of those two amylopectins was investaged so as to have a deep insight on the property of amylopectin in retrograded starches in this experiment.The results showed that the retrogradation rates of sweet potato and maize amylopectins were 2.5% and 1.6% respectively. The maximum visible absorption wavelength of amylopectins attached with iodine liquid before and after retrogradation were627.4nm and 570.4nm for sweet potato amylopectin, 569.8nm and 568.8nm for maize amylopectin.The results of IR spectra showed that there were lipids in sweet potato and maize amylopectin, but those lipids disappeared after those amylopectins retrograded again. The rates of intensities of bands at 881 /1020cm- 1or 660 /1020cm- 1in retrograded amylopectin might represent the rates of amorphous /crystalline regions. O- H stretching vibration of amylopectin should be around 1605cm- 1when protein and lipid were absent in amylopectin. Sweet potato amylopectin was more likely to retrograde than maize amylopectin.