*3.9. SEM*

SEM was employed to observe the microstructure of the lyophilized powder (Figure 5). The figures indicated significant differences between the powder with and without the trehalose. The structure of powders with trehalose was broken glass shaped and had miscellaneous irregular sizes and shapes. However, the surfaces were smoother than that of samples in the control group. The visible holes and fractures could be observed in the outer surfaces of powder which was consistent with the characteristics of added sugars and reflected the presence of trehalose.

**Figure 5.** The SEM images of the pure royal jelly lyophilized powder (**A**,**B**) and trehalose-royal jelly lyophilized powder (TR 5) (**C**,**D**).
