用小角X射线散射(small-angle X-ray scattering,SAXS)波谱可以定量分析淀粉的片层结构,但缺乏波谱数据分析软件而且需要专业的数学公式推导,严重制约了SAXS在淀粉研究中的应用.本文建立了一种简单的作图分析方法,可定量测定SAXS波谱中的淀粉片层结构信息(峰强度、峰位置、半峰宽度和片层距离).我们用该方法定量测定了不同晶体类型淀粉、不同直链淀粉含量的水稻淀粉、酸不溶淀粉和热不溶淀粉的SAXS波谱参数.结果表明,片层结构与淀粉的植物来源有关,而与淀粉晶体类型没有直接的相关性.相同植物来源的淀粉,其直链淀粉含量与SAXS峰强度和半峰宽度呈显著负相关而与片层距离呈正相关.酸水解不影响淀粉片层厚度,但明显改变片层峰强度和半峰宽度.加热处理也不影响淀粉片层厚度,但破坏淀粉晶体结构导致片层峰强度随温度升高逐渐降低直至消失.该定量作图分析法操作简单、重复性好、可信度高,可以在作物淀粉研究中广泛应用.%Small-angle X-ray scattering (SAXS) spectrum can be used to quantify the lamellar structure of starch. However, the spectrum analysis lacks a special data analysis software and needs complicated mathematical equations for it, which seriously restricts the applications of SAXS technology in starch studies. In this study, a simple graphical method was established to quanti-tatively measure the SAXS spectrum parameters (peak intensity, peak position, peak width at half maximum, and lamellar dis-tance). These parameters can reflect the information of starch lamellar structure. The SAXS spectra of starch with different crystal types, rice starch with different amylose contents, and acid-modified and gelatinized starch were all analyzed using the graphical method, showing that the lamellar structure of starch was related with the plant origin, but had no direct relationship with crystal types. For the starch from the same plant origin, the amylose content was significantly negatively correlated with peak intensity and peak width at half maximum, and positively correlated with lamellar distance of SAXS spectrum. The acid hydrolysis had no effect on lamellar distance of starch, but changed the peak intensity and peak width at half maximum of SAXS spectrum. Heating treatment also had no effect on lamellar distance of starch, but destroyed the crystalline structure, leading to the gradual decrease, even disappearance of peak intensity with increasing heating temperature. This study indicated that the quantitative graphical method is simple, good repeatable, and highly credible, and could be widely used in crop starch studies.
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