Infrared Spectroscopy Study on the Crystal Structure of Modified Starch

【Objective】The objective of this paper is to characterize the aggregation state structure of modified starch using infrared spectrometry.【Method】For the 1 300-800 cm-1 region, the FTIR spectra of modified starch were deconvoluted Voigt-type equations for all found peaks. The areas of deconvoluted peaks at approximate. 1 047, 1 022 and 980 cm-1 were obtained and the area ratios of 980/1 022, 980/1 047, (980+1 047)/1 022 and 980/(1 022+1 047) cm-1 were analyzed for the effect of modification on the starch crystalline structure. Then the result was compared with that of X-ray diffractometry.【Result】The area ratios of 980/1022, 980/1 047, (980+1 047)/1 022 and 980/(1 022+1 047) cm-1 were decreased as the degree of acetification increased which indicated that acetification induced a decrease of crystallinity of starch. And the crystal structure changed from A-type to V-type. For the cross-linking of POCl3, the area ratios of 980/1 022, 980/1 047, (980+1 047)/1 022 and 980/(1 022+1 047) cm-1 were also decreased as the degree of cross-linking but the decrease was little compared to that of acetification. The result indicated that cross-linking of POCl3 had little effect on the starch crystal structure【.Conclusion】The results suggest that the infrared spectrometry can characterize the chain structure of modified starch as well as the aggregation state structure for the agreement of the results of the X-ray diffractometry.