Preparation of crystalline by the method of acid-enzyme hydrolysis
After maize or potato starches were hydrolyzed by acid and(or) enzyme,the B-type crystallite starch can be obtained by a sequent of treatment: dissolution,filtration,crystallization,washing with distilled water,and air dryness.The A-type crystallite starch can be formed by the dissolution and re-crystallization at room temperature of B-type crystallite.The crystallite starches were characterized with scanning electron microscope(SEM),X-ray diffraction,differential thermal analysis(DTA) and gel pervasion chromatogram(GPC).The analysis results show that: the crystallite starches with the average diameter of about 2~7 μm were near globes;The crystallinity of A-type and B-type crystallite of maize starch were 76.33% and 81.3% respectively;and the crystallinity of A-type and B-type crystallite of potato starch were 57.3% and 71.9% respectively;B-type crystallite had a single peak of endothermic heat,but the A-type crystallite had another smaller peaks at about 85 ℃;The degrees of polymerization of crystallite of maize and potato starch were about 14 and 19 glucose units.