Research On The Affects Of Acid-enzyme Catalyzed Hydrolyzation On The Structure And Properties Of Starch Crystal

This dissertation uses catalyze-hydrolyzed method to investigate the crystal structure of starches expecting to form the theoretical groundwork of the uses of starch. In this paper, we make exploration on the factors affecting the crystal type of starch crystallite in the following aspects:1. Acid-catalyze hydrolysis. The relative crystallinity of the residues of maize starch and potato starch gradually increased with the increase of hydrolysis time, but the crystal type of which didn't changed. B-Type starch crystallites can be formed from dissolving and frozen-crystallizing the acid-hydrolyzed maize starch. B-type crystallite can be made into A-type crystallite by re-crystallizing under the conditions of higher concentration and room temperature. The crystallinities of A- and B-type crystallite are respectively 75% and 83%, the average molecular weight of them are respectively 2300 and 2339 with average degree of polymerization (DP) 14.4. A- and B-type crystallite of potato starch come into being by taking the same method as maize starch.2. Enzyme-catalyze hydrolysis. Lacunaria maize starch can be resulted from theα-amylose-catalyze hydrolysis, but the surface of potato starch was just eroded under the same condition. The crystallinity of starches can not be increased through theα-amylose-catalyze hydrolysis. The B-type crystallite can be formed by pasting, debranching and crystallizing the maize starch, potato starch and enzyme-hydrolyzed maize starch.3. Acid-enzyme catalyzes hydrolysis. The better crystallite can be obtained by homogeneously debranching and crystallizing the acid-hydrolyzed starch. Besides the crystallinity increases as the hydrolysis time lasts. The crystallite products of maize and potato starch have the same average diameter about 4μm, respective DP of peak values being 14 and 19. B-type crystallite has stronger enzyme-hydrolyzing resistance than A-type. The sensitivity of starches is improved after being acid-hydrolyzed, and the A-type crystallite has the maximal sensitivity to enzyme-catalyze hydrolysis.4. The influence factors of crystallite type. The glass transition temperatures (Tg) of amorphous regions of both starches and acid-hydrolyzed starches are highly dependent on the water contents. However the starch amorphous regions in a rubber state cannot produce dispersed diffraction diagrams. It nearly needs one water molecule for each glucose unit in A-type crystallite and three water molecules in B-type crystallite. It is favorable to form A-type crystallite at a higher temperature and concentration. On the contrary, it is favorable to form B-type crystallite at the lower temperature and concentration.