Spinach is rich in vitamin C and mineral nutrients, but it is bitter because it contains more fumaric acid. The oxalic acid contained in spinach is an organic acid. It can directly react with calcium in human body to form calcium oxalate precipitation. It affects the absorption of calcium by human body. If eaten raw, it can cause acute renal failure.
In addition, oxalic acid can hinder calcium absorption, cause hypocalcemia, and even endanger the function of kidney and liver. Therefore, spinach can not be washed and cut when making soup, and then directly sprinkled in the soup for consumption, let alone directly cooking and eating.
The cooking method is to wash and cut the spinach, put it in a boiling pot for a little time, and immediately fish it in cold water to cool down. In this process, more than 80% oxalic acid in spinach can be removed. Only after such operation can cooking be carried out again, which is no longer astringent on the taste.