[FTIR and XRD analysis of the enzymatic degradation of crosslinked starch microspheres]

Crosslinked starch microspheres (CSM) were prepared by crosslinking of soluble starch and N, N'-methylene-bis-acrylamide in inverse suspension. In order to describe the enzymatic degradation of CSM in this experiment, soluble starch, CSM and CSM's degradation product obtained from the simulated intestinal fluid in different time were analysed by Fourier transform infrared spectroscopy (FTIR) and X-ray diffractometer (XRD). The FTIR and SEM results showed that the CSM's crosslinking structure could be maintained steady in digested liquid within 3 hours. The intensity at 1,090 cm(-1) related to bending vibration bands of C--O--C, the amide band I and the amide band II became weaker in 3-12 hours along with the process of the enzymatic degradation, indicating the degradation of the molecular chain of starch and the depolymerization of the cross-linking structure. And then the disappearing of the amide band I and the amide band II indicated that the crosslinking structure was totally destructed after 12 hours and thereafter the enzymatic degradation was consistent with soluble starch. The XRD results proved that after 12 hours the CSM's degradation was similar to starch's degradation, their non-crystalline parts were decomposed, and their degree of crystallinity increased with the development of the degradation, but did not exceed the crystallinity of soluble starch.