Before making spinach soup, spinach should be blanched. Spinach should be blanched to remove oxalic acid because it contains oxalic acid, which will combine with free calcium ions in the body to produce calcium oxalate crystals, so you should blanch spinach to remove oxalic acid when you eat it. Although oxalic acid is soluble in water, it is not broken down by heat, so blanching spinach in boiling water does not break down the oxalic acid, but rather dilutes it.

When making spinach soup, if you cook spinach directly and drink the soup, you can drink the soup, which is equivalent to not reduce the intake of oxalic acid, oxalic acid is just dispersed to two places into the body. And after blanching and cooking to remove the blanching water, spinach oxalic acid content is greatly reduced. In the process of blanching to remove oxalic acid, it is inevitable that the loss of some other nutrients dissolved in water, leafy greens in the blanching process, the loss of water-soluble vitamins between 30% -50%.