Using seven varieties of roasted sesame seeds, we examined the relationship between the fracture properties and the internal structure of roasted seeds. Analysis of fracture properties revealed significant differences across the samples in terms of fracture force and fracture strain at the biggest fracture point, and in the number of small fractures (p<0.05). Analysis of the cross-sectional structure revealed significant differences across the samples in the size of the void at the center of the sesame seed and in the overall thickness of the seed (p<0.05). Strong negative correlations were found for the center-void-to-seed thickness ratio against fracture force and fracture strain at the biggest fracture point. Moreover, fracture properties and cross-sectional structure were strongly correlated with sensory evaluations of crispness. Hence we concluded that the presence of a void in the central area of a seed decreases the necessary fracture force, resulting in a crispy texture.