红外光谱技术在淀粉粒有序结构分析中的应用

傅里叶变换红外光谱技术(FTIR)可用于研究淀粉粒的有序结构，包括透射模式和衰减全反射模式2种。本文探讨不同去卷积设置条件对FTIR波谱的影响，并分析FTIR在淀粉粒有序结构分析中的应用。研究结果表明，不同去卷积设置对FTIR波谱和相关峰强度影响较大，以半峰宽19 cm^-1和增强因子1.9的设置对FTIR原始波谱去卷积，获得的结果较好。天然淀粉晶体类型不同，其FTIR波谱有差异，表现在马铃薯和山药淀粉的衰减全反射FTIR波谱相似，与水稻淀粉明显不同；水稻和马铃薯淀粉透射FTIR波谱相似，与山药淀粉明显不同。淀粉中的水分含量影响衰减全反射FTIR波谱，当水分含量超过60%时，对波谱分析结果基本没有影响。酸水解优先降解淀粉粒无定形区的结构成分，提高淀粉粒的有序度。淀粉葡糖苷酶水解淀粉对淀粉粒外部区域的有序度影响不大，但明显提高整个淀粉粒的有序度。不同品质稻米淀粉的衰减全反射FTIR波谱相似。上述研究结果为应用FTIR分析淀粉粒有序结构提供重要的参考作用。

Applications of Infrared Spectroscopy in the Analysis of Ordered Structure of Starch Grain

Fourier transform infrared spectroscopy (FTIR) is used to study the ordered structure of starch grain, which has two modes: transmittance and attenuated total reflectance (ATR). In this paper, the different deconvolution parameters of spectra were applied to compare their effects on FTIR spectra in studying the ordered structure of starch grain. The results indicated that the different deconvolution parameters had significant effects on FTIR spectra and the intensities of relative peaks. The peak half-width of 19 cm 1 and the resolution enhancement factor of 1.9 were ideal deconvolution parameters of spectra to obtain the better results. Native starches had A, B, and C three types of crystalline, their FTIR spectra showed some differences. Potato and Chinese yam starches had similar ATR-FTIR spectra, which were different from that of rice starch. However, rice and potato starches had similar transmittance-FTIR spectra, which were different from that of Chinese yam starch. The water content of sam- ple affected the spectra of ATR-FTIR, but this effect was not detected when water content exceeded 60%. The ATR-FTIR spectra showed that the hydrolysis of amorphous structure in starch grain was faster than that of ordered structure during acid treatment. The ordered degree of structure in starch grain increased with increasing time of acid hydrolysis. The amyloglucosidase hydrolysis had no significant effect on the ordered degree of structure at the outside of starch grain by the ATR-FTIR spectra, but the ordered degree of structure of whole starch grain significantly increased with enzyme hydrolysis according to the transmittance-FTIR spectra. The amylose content is an important physicochemical property in determining the starch quality. Rice starches with dif- ferent amylose contents showed the similar ATR-FTIR spectra. These results would be very useful for the application of FTIR to the analysis of ordered structure of starch grain.