Three strokes to identify "stained" sesame seeds.
A look of color, dyed black and bright, spotless; no color of different colors, but also mixed with individual white sesame seeds.
Second smell of taste, no staining of the smell of sesame seeds, dyed not only not fragrant, but also may have ink smell.
Three dipped in a napkin dipped in water, the normal sesame seeds will not fade, if the paper immediately darkened, and sure to stain sesame seeds. Some black rice may also be dyed, the easiest way to judge is to bite the teeth, which is white, it must be dyed with white rice.