Good quality has a think and tight, reddish brown cork, a solid and heavy cortex, and a yellowish white and powdery surface on cross section. Roots with a rough, greyish brown surface, loose texture, and a dark yellow surface on cross section are of inferior quality. Brownish black roots with a yellowish brown surface on cross section and a bitter taste should not be used. The peeled product is considered to be of better quality.
