Code of Federal Regulations Title 7. Agriculture § 7.51.2740 Minor defects

(a) Skin discoloration which is dark brown, dark gray, dark blue or black and covers more than one-fourth of the surface;

(b) Flesh discoloration which is darker than a light yellow color or consists of more than a slight yellow pitting of the flesh;

(c) Sprout extending more than one-eighth of an inch from the tip of the kernel;  and,

(d) Dirt when the surface of the kernel is distinctly dirty, and its appearance is materially affected.