The blackening of acorns should be mildew caused by deterioration. The interior of acorns should usually be white. Acorn: containing starch, edible and bitter. Also known as acorns, acorns and chestnuts. Oak. The fruit of oak tree is rectangular, containing starch and a small amount of tannic acid, and its shell can be made into tannin extract. It is also called acorn or acorn. Some areas are called rubber bowls. Acorns are mainly produced in the eastern part of Hubei Province, China. Oak has a hard shell, reddish brown, peanut kernel, rich in starch, and the content is about 60%. It can not only be eaten, but also be used as raw material for sizing in textile industry. Acorn is one of the most important foods in early human life. It can also be made into acorn powder.