基于X-射线衍射及扫描电子显微镜的马铃薯淀粉掺伪鉴别

目的建立一种快速、准确鉴别市售马铃薯淀粉掺伪的方法。方法将红薯、玉米及小麦淀粉按不同比例加入纯马铃薯淀粉中,通过X-射线衍射(X-ray diffraction,XRD)对样品进行结晶结构分析,并结合扫描电子显微镜(scanning electron microscope,SEM)进行微观形貌观察。结果利用结晶类型差异,XRD可初步判别马铃薯淀粉样品是否掺入上述3种淀粉,进一步采用SEM可观察到含量1%的掺伪淀粉并对其种类进行区分。在市售12批次马铃薯淀粉中的7批次中发现存在掺伪现象,其中2批次利用扫描电镜未观察到马铃薯淀粉(小于1%)。结论市售马铃薯淀粉掺伪现象严重,利用X-射线衍射及扫描电子显微镜可快速、准确地鉴别马铃薯淀粉掺伪情况。

Detection and identification of adulterated substitution in potato starch by X-ray diffraction and scanning electron microscope

Objective To establish a rapid and accurate method to identify potato starch adulteration. Methods Sweet potato, maize and wheat starch were added into pure potato starch by different proportions. The crystal structures of the samples were analyzed by X-ray diffraction (XRD), and microscopic appearance was observed by scanning electron microscope (SEM). Results Distinct types of crystal structures from XRD could draw conclusion of whether sweet potato starch, maize starch and wheat starch were added to the potato starch powder as cheap substitute. Moreover, 1% of non-potato starch could be detected, and further whose components could be discerned by SEM. A total of 12 products bought in market had been put under inspection, and 7 of them had been uncovered of using substitutive starch, 2 of which no potato starch had been observed by SEM. Conclusion The adulteration of potato starch in the market is serious. Using X-ray diffraction and scanning electron microscope can identify potato starch adulteration quickly and accurately.