Objective The study aims to establish a convenient and effective method to observe the ultrastructures of pericarp and endosperm in the kernels of sweet corn simultaneously based on the scanning electron microscopy (SEM), which can be applied to assess the taste quality of the kernels from different sweet corn varieties.

Method The ultrastructures of pericarp and starch granules of the mature kernels were compared after they were prepared with three different sample treatment methods, including glutaraldehyde fixation method, low-heat drying method and direct sample preparation method.

Result Glutaraldehyde fixation method could display the structure and thickness of pericarp cells well as well as the properties and spatial distribution of starch granules of the kernel, which was a relatively ideal and convenient pretreatment method for SEM observation of the ultrastructures of pericarp and endosperm in the kernels. Glutaraldehyde fixation method was then applied to compare the differences at the ultrastructural level among four sweet corn varieties. The results showed that there were significant differences among different types of sweet corn kernels in pericarp structure, endosperm starch space, starch granule size and their distribution. The different ultrastructure characteristics were closely related to the different taste qualities of sweet corn kernels.

Conclusion Glutaraldehyde fixation is a convenient and effective method to obtain the ultrastructures of pericarp and endosperm in the kernels of sweet corn, which can be used to assess the taste quality of sweet corn at the ultrastructural level and the research on the ultrastructure characteristics of pericarp and starch granules in sweet corn kernels, providing a method to support the improvement of sweet corn varities.