The way to peel the lotus root: first use water to soak the lotus root, and then use the cleaning ball of metal wire to rub. Not only is it fast and thin, even the skin in the small concave areas can be removed, but also maintains its original intact shape, both white and round. If you scrape the skin with a scraper, the little pits in the recesses will be hard to scrape clean. In fact, lotus root can be eaten without scraping the skin! Never use an iron pot to cook lotus root. Lotus root contains a chemical called tannin, also known as tannin. When lotus root is cut and peeled, it turns brown when exposed to air. The discoloration is due to oxidation, where the phenols in the tannins produce polymers of quinone to form brown pigment, also known as melanin. To prevent discoloration, peeled and cut fruits and vegetables can be soaked in water or lightly salted water to isolate them from the air, which can prevent oxidative discoloration. In addition, another reason for tannin discoloration is to generate dark-colored tannin salts with metals, such as iron into blue or dark green. It is for these reasons, so do not use iron pots when cooking lotus root, to use casserole is appropriate; cut lotus root is best to use stainless steel knife.