1,,Peel a few grapes to eat.

2, use grape juice to wipe the black color of walnuts on your hands. If you don't have grapes on hand, pour a small amount of vinegar on your hands to clean them.

Expansion: walnut green skin contains walnut , α-hydrogenated walnut -4-glucose, tannin, gallic acid, walnut drunken alkaloids (C1OH6O3) and naive eye and so on. The unripened walnut contains a large amount of vitamin C. Therefore, it has both medical uses and can be used to make dyes. According to research reports walnut green peel can be extracted a brown dye, is an acid dye, specializing in dyeing wool and silk fabrics. Dyeing fastness can meet the general requirements of wool and silk fabrics. The residue after extraction contains protein, can be used as pig feed.