Surface Modification Mechanism of Cross-Linking and Acetylation, and Their Influence on Characteristics of High...

Through dual modification of high amylose corn starch (HACS), the surface modification mechanism of cross-linking and acetylation was mainly studied, and their effect on the physicochemical properties of HACS was further investigated. The variation in surface hydroxyl numbers showed that the influence of acetylation on the structure of particles was obviously different from cross-linking. Cross-linking was carried out only on the granule surface, whereas acetylation was finished not only on the surface but also in the interior of grains. Cross-linking could unevenly produce many micropores on the particle surface. The destruction level of HACS granules caused by acetylation was greater than that of cross-linking according to XRD. The surface hydroxyl groups were not distributed evenly on HACS particles. Cross-linking did not improve the freeze-thaw stability of HACS, but acetylation could improve its freeze-thaw stability. The variation in the blue value caused by cross-linking was more than by acetylation.

The surface modification mechanism of cross-linking and acetylation will provide the theoretical basis for industrial production of cross-linked starch, acetylated starch, and cross-linked acetylated starch. For the surface modification, the cross-linking degree was better evaluated by the surface hydroxyl group numbers than the conventional sedimentation volume method. The development of cross-linked acetylated high amylose corn starch as a new additive will further enlarge the application of high amylose corn starch in food, textile, medicine, and so on.