Amaranth must be blanched before cooking in order to maintain the nutrients of the dishes, cooking often advocate that "vegetables should be washed and then cut, do not use water to soak or blanch", but some dishes must be blanched before eating. Amaranth and other high content of oxalic acid, oxalic acid will be mixed with calcium in the food to form calcium oxalate, affecting the absorption of calcium in the body. The chemical name for oxalic acid is ethanedioic acid, which is characterized by its solubility in water. Therefore, by blanching amaranth in boiling water, a large amount of oxalic acid and nitrates, which are harmful to the human body, can be removed. However, the blanching method should be blanched with absolute oxygen.